SMITHSONIAN CONTRIBUTIONS TO BOTANY NUMBER 91 

Epidermal Features and Spikelet 

Micromorphology in Oryza 

and Related Genera 

(Poaceae: Oryzeae) 

Edward E. Terrell, Paul MI Peterson, 

and William P Wergin 

Smithsonian Institution Press 

Washington, D.C. 

200 1 
ABSTRACT 

Terrell, Edward E., Paul M. Peterson, and William P. Wergin. Epidermal Features and Spikelet Micromorphology in Oryza and Related Genera (Poaceae: Oryzeae). Smithsonian Contributions to Botany, number 91, 50 pages, 33 figures, 3 tables, appendix, 2001.-Using scanning 

electron microscopy, this study examines the spikelet morphology of sixteen species of Oryza, 

one species of Leersia, and one species each of the monotypic genera Porteresia and Rhynchoryza. A detailed discussion of the spikelet epidermal features and their relationship to the 

pedicel and cupule is presented. As the pedicel and cupule of species of Oryza are below the 

point of articulation of the spikelet, have similar epidermal features, and are free from the vascular cylinder that proceeds upward (distally) into the spikelet, we conclude that the pedicel 

cupules are not glumes but are merely expanded apices of the pedicels. An original data set of 

14 morphological characters was used to perform parsimony and UPGMA analyses. Of these 

14 characters, six describe the lemma, three describe the rachilla, two describe the glumes, two 

describe the articulation point and callus shape, and one describes the embryo. Our classification of Oryza recognizes three subgenera: Oryza subg. Oryza; 0. subg. Brachyantha, new 

combination and status; and 0. subg. Schlechteria, new combination and status. Within subgenus Oryza we recognize three sections: Oryza sect. Oryza (including 0. ser. Oryza and 0. ser. 

Latifoliae); 0. sect. Ridleyanae; and 0. sect. Padia. ~ 

OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is 

recorded in the Institution's annual report, Annals of the Smithsonian Institution. SER~ES COVER 

DESIGN: Leaf clearing from the katsura tree Cercidiphyllum japonicum Siebold and Zuccanni. 

Library of Congress Cataloging-in-Publication Data 

Terrell, Edward E. 

Epidermal features and spikelet micromorphology in Oryza and related genera (Poaceae:Oryzeae / Edward E. 

Terrell, Paul M. Peterson, and William P. Wergin. 

p. cm.-(Smithsonian contributions to botany ; no. 91) 

Includes bibliographical references (p.). 

1. Oryza. 2. Grasses. 1. Peterson, Paul M. 11. Wergin, William P. 111. Title. IV. Series. 

QKI .S2747 no. 91 [QK495.G4] 580 s4c2I [57 1.3'2491 00-0698 1 1 

@ The paper used in this publication meets the minimum requirements of the American 

National Standard for Permanence of Paper for Printed Library Materials 239.48-1 984. 
Contents 

Page 

Introduction ............................................................ 1 

MaterialandMethods .................................................. 2 

Acknowledgments ..................................................... 3 

Morphology of Oryza .................................................... 4 

Epidermis ............................................................ 4 

Pedicels and Cupules ................................................... 6 

Numerical Analyses ..................................................... 10 

Spikelets ............................................................ 4 

Embryo ............................................................. 5 

Comparative Morphology of Species of Oryza and Related Genera ................ 7 

Characters and Their States ........................................... 10 

UPGMAAnalysis .................................................. 10 

Parsimony Analysis ................................................. 11 

ClassificationofOryza .................................................. 11 

Appendix : Descriptions of Species Groups of Oryza .......................... 13 

Figures ............................................................... 15 

Literature Cited ........................................................ 49 

... 

111 

Epidermal Features and Spikelet 

Micromorphology in Oryza 

and Related Genera 

(Poaceae: Oryzeae) 

Edward E. Terrell, Paul MI Peterson, 

and William P Wergin 

Introduction 

The rice genus, Oryza, comprises approximately 22 species 

distributed in Asia, Africa, Australia, and the Americas. Using 

scanning electron microscopy this study examines the spikelet 

morphology of sixteen species of Oryza, one species of Leersia, and one species each of the monotypic genera Porteresia 

and Rhynchoryza. Previous studies have discussed the morphology and anatomy of the spikelets of Oryza (von Hohnel, 

1875; Van Breda de Haan, 191 1; Akemine, 1913; Graham, 

1913; Weatherwax, 1929; Roschevitz, 1931; Santos, 1933; 

Juliano and Aldama, 1937; Jacques-Felix, 1955; Tateoka, 

1962a, 1962b, 1963, 1964, 1965a, 1965b, 196%; Tateoka and 

Pancho, 1963; Chang and Bardenas, 1965; Nunez, 1968; Roy, 

1968; Katayama, 1969). Other papers employed scanning electron microscopy to illustrate parts of the rice spikelet (e.g., 

Maeda, 1972; Soni and Parry, 1973; Hoagland and Paul, 1978; 

Zee, 1981) or to describe silica localization in the spikelet tissues (Locci and Quaroni, 1975; Yoshida et al., 1962; Garrity et 

al., 1984). A previous study (Terrell et al., 1983) provided data 

Edward E. Terrell, research collaboratoc and Paul M. Peterson, Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, D. C. 20.560-01 66, U.S.A. William R 

Wergin, Nematology Laboratory, BA RC-East, Beltsville, Maryland 

20705, U. S. A. 

Review Chairman: Dan H. Nicolson. Department of Botany, National 

Museum of Natural History, Smithsonian Institution, Washington, 

Reviewers: M. R. Duvall, Department of Biological Sciences. Northern 

Illinois Universiv, DeKalb. Illinois, 6011.5-2861; S.A. Renvoize, Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 2AE. 

U. K. 

D.C. 20.560-0166. 

on the epidermal features of the spikelets of the related genus 

Leersia. These same features were investigated in the oryzoid 

genus Zizania by Terrell and Wergin (198 1). 

Three new species of Oryza were not included in this study 

because they were unavailable and are thought to be closely related to other species included in this study, so they were not 

expected to contribute new data. They are Oryza meridionalis 

N.Q. Ng from Australia (Ng et al., 1981), which appears to be 

closely related to 0. sativa and 0. rufipogon; 0. rhizomatis 

Vaughan from Sri Lanka (Vaughan, 1990), said by Vaughan to 

have the same genome as 0. officinalis and 0. eichingeri A. 

Peter; and 0. neocaledonica Morat from New Caledonia, apparently related to 0. meyeriana (Morat et al., 1994). Other 

taxa not included in our survey are 0. indandarnanica J.L. Ellis 

(Ellis, 1985a, 1985b), usually treated as a synonym of 0. meyeriana var. granulata (Vaughan, 1989); 0. glumipatula Steud., 

usually treated as a synonym of 0. rufipogon (Tateoka, 1963); 

0. nivara Sharma & Shastry, considered conspecific with 0. 

sativa (Duistermaat, 1987); 0. perennis Moench, shown to be a 

vaguely described name of uncertain application (Tateoka, 

1963; Clayton, 1968; Duistermaat, 1987). 

The purposes of this study are to (1) describe and compare 

the epidermal features of the spikelets in species of Oryza and 

related genera, (2) confirm the relative silicon contents of the 

spikelet structures, (3) investigate the importance of the morphological data, using cladistic and phenetic techniques, as 

suggested by comparative morphology, and (4) determine the 

taxonomic significance of the comparative morphology of the 

taxa. In addition, we have provided a provisional classification 

within Oryza recognizing three subgenera, three sections in 

subg. Oryza, and two series within sect. Oryza. 

I 
2 

MATERIAL AND METHODS 

The taxa examined in this study include 16 species of Oryza, 

and species of the following related genera: Porteresia coarctata, Rhynchoryza subulata, and Leersia nematostachya (Table 

1, which includes authors of scientific names). Specimens were 

obtained through the United States Department of Agriculture 

(USDA), Beltsville, Maryland; from the herbarium of the National Museum of Natural History, Smithsonian Institution 

(US); from the United States National Arboretum (NA); or 

from the Royal Botanic Gardens, Kew (K), with the assistance 

of Stephen A. Renvoize. The designations in Table 1 of IRRI 

and IITA, refer, respectively, to the International Rice Research 

Institute, Los Baiios, Philippines, and to the International Institute of Tropical Agriculture, Ibadan, Nigeria. Five accessions 

of 0. sativa came from the USDA Rice Experiment Station, 

Crowley, Louisiana. The original source of material, however, 

was not always known by these institutions. Eight collections 

of 0. sativa (Table 1) included certain cultivars and other specimens designated by USDA P.I. (Plant Introduction) numbers. 

Two cultivars, “Blackhull Red” and “Strawhull Red,” the socalled red rice, considered by rice growers as an unwelcome 

SMITHSONIAN CONTRIBUTIONS TO BOTANY 

weed, are herein presumed to be 0. sativa, although they possibly include genes from 0. rufipogon. Other examined accessions of 0. sativa include the cultivars “Dawn,” a long-grained 

rice; “Nortai,” a short-grained rice; and “Saturn,” a mediumgrained rice. Voucher specimens are deposited in the USDA 

Seed Collection at Beltsville, Maryland, or in the listed herbaria. 

All accessions were examined under a dissecting microscope 

and by scanning electron microscopy (SEM) at the USDA in 

Beltsville, Maryland. Specimens were air-dried, except for four 

of the 0. sativa accessions (cv. “Nortai” and those designated 

by P.I. numbers). To preserve turgidity in the microhairs of 

these latter accessions, tissues were chemically fixed in vials 

containing 3% glutaraldehyde in 0.05M phosphate buffer, pH 

6.8 at 22°C. Chemical fixation for 1.5 hr was followed by dehydration in an ethanol series and critical-point drying from 

liquid carbon dioxide. Next, the air-dried and the chemically 

fixed specimens were mounted on stubs, coated with 20 nm of 

gold-palladium in a Technics Hummer V sputtering device, and 

viewed in a Hitachi HHS-2R or Hitachi S-530 scanning electron microscope operating at 10-15 kV. Images of all the samples were recorded on Polaroid Type 55 P/N film. 

TABLE 1 .-Species of Otyza, Porteresia, Rhynchoryza, and Leersiu examined using SEM. The designations 

IRRl and IITA refer, respectively, to the International Rice Research Institute, Los BaRos, Philippines, and the 

International Institute of Tropical Agriculture, Ibadan, Nigeria. 

Species Source 

Oryza alta Swallen 

0. australiensis Domin 

0. barthii A. Chev. 

0. brachyanfha A. Chev. & Roehr. 

0. glaberrima Steud. 

0. grandiglumis (DOH) Prod. 

0. Iutfolia Desv. 

0. longistuminata A. Chev. & Roehr. 

0. meyeriana (Zoll. & Moritzi) Baill. 

0. meyeriana var. granulata (Nees 

0. minuta J. Presl 

0. oflcinalis Wall. ex G. Watt 

0. punctata Kotschy ex Steud. 

0. ridleyi Ho0k.f. 

0. rujpogon Griff. 

0. satiwa L. cv. Strawhull Red 

0. sutiwu L. cv. Blackhull Red 

0. sativa L. cv. Dawn 

0. satiwa L. cv. Nortai 

0. sativa L. cv. Saturn 

0. satiwa L. (P.I. 160978) 

0. satiwa L. (P.I. 373210) 

0. satiwa L. (P.I. 391823) 

0. schlechteri Pilg. 

Porteresia courctata (Roxb.) Tateoka 

Rhynchoryzu subulata (Nees) Baill. 

Leersiu nematostuchva Launert 

&Am. ex G.Watt) Duist. 

USDA reference collection, Brazil 

Blake 13641 (K), Queensland 

IRRI 1001 19, French Sudan; IRRl 100224, Gambia 

IRRI 101236, Mali; Richard.q 917/ (K), Zambia 

IITA, TOG5833, unknown source; IITA, TOG7141, unknown 

Archer 8376 (US), Brazil 

Standley 89614 (NA), Guatemala 

IRRI 101199, Cameroun 

Strain “1353 (K), N. Borneo, cult., Japan; Meijer 5000/ (US), 

IRRI 100162, Malaya; Kostermans 1200 (US), Thailand 

source 

Sabah; Merrill 7244 (US), Palawan, Philippines 

IRRI 101 124, Philippines 

IRRI, CAHUP 17423, Madagascar 

IRRl 100126, India 

IRRI 100820, Buwalda 6339 (US), Sumatra 

Clayton 5933 (US), Sri Lanka 

USDA,Crowley, LA., U.S.A. 

USDA, Crowley, LA., U.S.A. 

USDA, Crowley, LA., U.S.A. 

USDA, Crowley, LA., U.S.A. 

USDA, Crowley, LA., U.S.A. 

USDA, from China 

IRRI 11481, Japan via USDA 

lRRl4213, Philippines via USDA 

Pulle 377 (K), New Guinea 

IRRI, collected by D. Auch, Bangadesh 

IRRl 100913, Argentina 

Simon & Williamson 1987 (K), Zambia 
NUMBER 91 3 

TABLE 2.-Data set for 16 species of Oryza, and three outgroup species. (Character states from page 10; question 

marks=inapplicable data; - = data missing.) 

Species 

0. sativa 

0. barthii 

0. glaberrima 

0. longistaminata 

0. rujpogon 

0. alta 

0. australiensis 

0. grandiglumis 

0. latifolia 

0. minuta 

0. ofJcinalis 

0. punctata 

0. meyeriana var. meyeriana 

0. meyeriana var. granulata 

0. ridleyi 

0. brachyantha 

0. schlechteri 

Porteresia coarctata 

Rhynchotyza subulata 

Leersia nematostachya 

21221111112211 

21221111112211 

21221111112211 

21221111112211 

21221111112211 

11121211112211 

11121211112211 

11121211112211 

11121211112211 

11121211112211 

11121211112211 

11121211112211 

11211321132222 

11211321132222 

11211321122212 

22312??12?2212 

11122??32?122- 

13212??12?2113 

11232??2142111 

22??2??12?121- 

For energy dispersive X-ray (EDX) analysis, flat specimens, 

which had been sputter-coated with gold-palladium, were inserted into the Hitachi HHS-2R scanning electron microscope 

and tilted to 45 degrees. X-ray mapping and line analysis for 

silicon were performed at 25 kV with a Kevex 5 100 containing 

a 30 mm2 Mark V detector. The excitation window was set at 

1.62-1.86 KeV. The maps represent X-rays that were collected 

during a 200 second exposure on Polaroid Type 55 PIN film. 

A character list and their states, with a discussion and explanation, were used in all ensuing numerical analyses (see page 

10). The taxa were scored for 14 morphological characters (for 

data see Table 2). Of these 14 characters, six describe the 

lemma, three describe the rachilla, two describe the glumes, 

two describe the articulation point and callus shape, and one 

describes the embryo. Characters used in the phenetic analysis 

were incorporated in the cladistic analysis unless they were 

phylogenetically uninformative. 

A preliminary unweighted pair-group mathematical average 

(UPGMA) phenetic evaluation of the morphological variation 

was made among 16 species of Oryza. The phenetic analysis 

was carried out with the UPGMA option in phylogenetic analysis, using parsimony (PAUP) test version 4d65 (issued 8 April 

1999; Swofford, 1993). 

In the parsimony (PAUP) analyses, files were input in nexus 

format, using the heuristic search option with tree bisection-reconnection (TBR), mulpars (multiple parsimonious trees) option, and a simple addition sequence. Strict consensus trees 

were calculated for the overall analysis. Although this technique has been widely criticized (e.g., West and Faith, 1990), it 

does provide an easy assessment for particular clades within a 

topology. Only parsimony-informative characters were used in 

the cladistic analysis. Bootstrap values were calculated using a 

MaxTrees setting of 100 or more, added sequentially, and are 

only reported where values are greater than 50% majority rule 

in the strict consensus tree. Multistate characters were treated 

as polymorphisms and were scored as unordered. 

ACKNOWLEDGMENTS 

We wish to express our thanks to George White, formerly 

USDA Plant Introduction Officer, Beltsville, Maryland, and to 

the following persons for providing plant samples: T.T. Chang, 

N.E. Jodon, A.J. Oakes, and Stephen A. Renvoize. The herbarium curators at K and US helpfully provided access to their 

collections. We thank Christopher Pooley for digitizing the 

SEM images and for preparing the plates that illustrate this 

study. Robert H. Miller prepared helphl anatomical sections of 
4 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

lemmas. We especially thank the reviewers of the manuscript 

for suggesting modifications that improved the manuscript: 

Melvin R. Duvall, Bao-Rong Lu, Stephen A. Renvoize, and 

Robert J. Soreng. 

Morphology of Oryza 

EPIDERMIS 

Terminology follows Metcalfe (1960) and Terrell et al. 

(1983), and we follow Snow (1996) in referring to prickles instead of prickle hairs. 

One of the most conspicuous and common epidermal structures in the spikelets of Oryza are the bicellular microhairs. 

These have a short basal cell, about one-third to two-fifths as 

long as the microhair, and a slightly longer apical cell. The latter is especially fragile and frequently breaks off. Microhairs 

are usually collapsed in air-dried material and are turgid only in 

critical-point dried material (Figure 2). The living microhairs 

are filled with fluid, as illustrated for Leersia and Zizania (Terrell and Wergin, 1981; Terrell et al., 1983). Although we note 

differences in the size and shape of microhairs (e.g., Figures 

2c, 4c, 16b,d), a much more detailed study of them would be 

necessary to determine their significance. 

Prickles are one-celled, rigid, pointed structures that vary 

greatly in size and shape. They are one of the most abundant 

and widespread epidermal features of the pedicels and spikelets 

in Oryza. Prickles are commonly visible with the naked eye 

where they occur in rows over the nerves and margins of the 

lemmas and paleas. Under the microscope they are seen to occupy the ridges or the furrows of the lemmas and paleas, and in 

certain species they may arise from basal plates that are fused 

with the surrounding tissue (Figure 6). 

Silica bodies are siliceous structures firmly embedded in the 

epidermis. Their shapes vary greatly from 2- to 4-lobed to almost entire or with irregular sinuses (e.g., Figures 3b, llb) Silica bodies are primarily found in the rachillas, pedicels, calluses, glumes, and lemma apices. 

Stomata occur in certain parts of the spikelets and in pedicels 

(e.g., Figure 2b,4 but are commonly absent from the main 

parts of the lemmas and paleas. 

Papillae occur in all species on most parts of the spikelets. 

They are usually small rounded structures but can be large 

(e.g., Figures 2d, 6,9), and their apices may have minute pores. 

Tubercles are specialized, siliceous, 1 - to 4-pronged structures that form the most conspicuous elements of the lemma 

and palea (e.g., Figure 4). They provide a formidable armor 

unique to Oryza. The tubercles are further described in the subsequent section. 

We found a few, scattered, large, 3- or 4-celled hairs in 0. saliva cultivars “Nortai” and “Saturn.” They occurred in the 

lemma furrows among the usual appressed two-celled microhairs, with which they contrasted in being larger and ascending 

or erect. They were distributed randomly-near or along the 

lemma margins and appeared to replace microhairs. JacquesFelix (1955) alluded to the presence of such hairs on the lemmas of 0. glaberrima, a species closely related to 0. saliva. 

SPIKELETS 

Parts of the spikelet examined included the callus, the oryzal 

rachilla, the paired glumes (sterile lemmas), lemma, palea, apicular knobs, and awns. Above the point of articulation of the 

spikelet is a thickened, indurate structure, referred to as the callus. It sometimes bears silica bodies and/or stomata. Within 

Oryza we define the callus as extending from the point of articulation of the spikelets to the base of the first and second 

glumes. In species of Oryza, there is considerable variation in 

the size of the callus, and it is usually fused with the glume 

bases. In 0. brachyantha and Leersia nematostachya, the unusually large callus, in the absence of a stipe or rachilla, forms 

a solid, indurate, homogeneous structure extending from the 

spikelet base to the base of the lemma (Figures 21, 28). We refer to this as a stipitate callus (term suggested by W.D. Clayton 

in 1983 and communicated to Terrell in correspondence with 

S.A. Renvoize). 

The pedicel cupules, sometimes considered to be glumes, are 

discussed in the subsequent section. We consider the true 

glumes to be the paired, rigid, often lanceolate structures 

(“sterile or empty lemmas”) below the lemmas. Each glume 

has one vascular bundle. These glumes are further differentiated from the pedicels and spikelet parts by having few or no 

epidermal features, usually only prickles, scattered silica bodies, or scattered microhairs (e.g., Figures 36, 96, lob). The 

glumes differ further from other parts of the spikelet by their 

position and shape, and they resemble the glumes of other 

grass tribes and genera because they are opposite each other or, 

in some species, somewhat offset from or alternate with each 

other. 

The structure generally called the rachilla in Oryza (e.g., 

Graham, 1913; Chang and Bardenas, 1965) is in the same position relative to the lemma that the rachilla occupies in some 

other grass tribes. In these other grasses, however, the rachilla 

is usually very slender or filiform and appears to be pedicellike or stipoid. In 0. sativa and related species, this structure is 

somewhat subglobose (e.g., Figure 3), and its surface is 

densely covered with small projections rather similar to the 

much larger tubercles on the lemma and palea. We refer to this 

condition as a muricate rachilla. The projections on the muricate rachillas are jumbled and locally coalesced (Figure 3c), in 

contrast to the orderly rows of tubercles in the lemmas and 

paleas. A few microhairs occur on the rachilla in certain species. In species of Oryza not closely related to 0. saliva, the 

rachilla surface is not muricate and instead has silica bodies or 

lacks conspicuous epidermal features. These species (especially 0. meyeriana and 0. ridleyi) usually have cylindrical or 

broadly cylindrical rachillas (Figures 16a. 19c). We herein refer to both kinds of rachillas as oryzal rachillas because they 

are unlike the stipoid rachillas seen in other kinds of grasses. 
NUMBER 91 5 

Whether all of these grass rachillas are homologous remains to 

be determined. 

The principal parts of the Oryza spikelet are the lemma and 

palea that are attached along their overlapping margins. The 

lemma is always larger, but the lemma and palea are identical in 

epidermal morphology. The palea has three nerves rather than 

two, as is usual in grasses, and several authors (e.g., Nunez, 

1968) have discussed the origin and homology of the Oryza 

palea. We have not explored this problem and tentatively continue to use the term palea. The lemma and palea of 0. sativa 

and closely related species bear large and conspicuous siliceous 

tubercles arranged in vertical tiers and horizontal rows that alternate with longitudinal furrows (e.g., Figure 4), resulting in 

one of the most remarkably specialized epidermal surfaces in 

the grasses. The tubercles usually have 1 to 4 conspicuous apical prongs. They may be apically shriveled or with terminal 

pores. Tubercles show considerable variation in size and shape, 

sometimes are dotted with papillae (e.g., 0. glaberrima; Figure 

94, and may have coalescent basal plates that intrude into the 

adjacent furrows (e.g., 0. meyeriana; Figures 16, 18). The furrows are lined with appressed microhairs, with one microhair 

attached opposite each tubercle (Figure 4). At intervals the microhairs may be replaced by relatively large prickles. 

The anatomical and morphological features of the lemmas 

and paleas were briefly described by Kihara and Katayama 

(1959) and Katayama (1969). They also mentioned differences 

in the tubercles among four sections of Otyza and credited Roshevitz (193 1) with previously recognizing the taxonomic importance of lemma surfaces in Oryza. 

We used energy dispersive X-ray (EDX) analysis to chart the 

presence of silicon in the tubercles (Figure 5). A line scan 

shows the highest concentrations of silicon in the apices of the 

tubercles, whereas a line scan that intercepts the microhairs 

elsewhere or in the furrows showed less or no silicon. The Xray map also illustrated the high silicon concentrations in the 

tubercles. 

The apices or apiculus of the lemma and palea differ from 

the main body of the lemma and palea (Graham, 1913; Chang 

and Bardenas, 1965). The tubercles near the apices are jumbled 

and coalesced with each other (Figure 6) and occur with microhairs, prickles, and stomata (stomata are lacking in the main 

body of the lemma). Some prickles of the lemma and palea apices have large, plate-like bases that fuse or coalesce and the papillae may be numerous. Oryza sativa and related species have 

two small, knob-like swellings situated on the apiculus of the 

lemma near the base of the awn (Figures 6, 7). These knobs 

were described by rice specialists (Chang and Bardenas, 1965) 

and are said to be the termini of the lateral nerves of the lemma 

(Launert, 1965). Roy (1 968) found that the nerves of the 

lemma converge and interconnect in the apicular region and 

continue into the awn. He proposed the term “apicular node” to 

designate the apicular region where interconnection of vascular 

elements take place (1968: 10). He did not clearly designate a 

term for the external, knob-like structures, and we herein refer 

to them as apicular knobs. SEM micrographs show that the apicular knobs and the adjacent lemma and palea apices have the 

same surface epidermal features (Figure 6). We found that apicular knobs occur only in the five species of the 0. sativa 

group (0. barthii, 0. glaberrima, 0. longistaminata, 0. rujipogon, and 0. sativa) and in 0. brachyantha. They were not 

found and are believed to be absent in the other species of 

Oryza. This characteristic is sometimes very hard to interpret, 

however, and because we were unable to make an unambiguous determination of presencelabsence in all species of this 

study, it was omitted from the numerical analyses. 

Awn anatomy in 0. sativa was described by Juliano and Aldama (I 937). SEM views of awns appeared in Maeda (1 972) 

and in Hoagland and Paul (1 978). Roy (1 968) described and illustrated details of awn anatomy in three species of Oryza and 

found that their awns had a single, ventral, vascular bundle. 

Otyza sativa and 0. australiensis have two groups of phloem 

and one of xylem; however, 0. brachyantha has two groups of 

phloem and two of xylem. Roy (1 968) considered the latter 

species to have the plesiomorphic state. 

Awns occur in most of the species of Oryza but are absent in 

the 0. meyeriana complex and in 0. schlechteri. They may or 

may not be present in 0. sativa. In the 0. sativa group (0. barthii, 0. glaberrima, 0. longistaminata, 0. ru$pogon, and 0. 

sativa) and in 0. brachyantha, the bases of the awns show a 

clear demarcation in epidermal features from the adjoining 

lemma apices (Figure 22c). In the 0. latifolia group (0. alta, 

0. australiensis, 0. eichingeri, 0. grandiglumis, 0. latifolia, 

0. minuta, 0. oflcinalis, and 0. punctata), there is no such demarcation other than sometimes a diminution in the density of 

prickles on the awns. Whether this demarcation in the 0. sativa 

group is correlated with the presence of apicular knobs remains 

to be determined. 

The epidermal features present on awns are listed in the individual descriptions and are shown in several micrographs (e.g., 

Figure 7). Commonly, awns have prickles, microhairs, and 

sometimes silica bodies and stomata. Awns in two cultivars of 

red rice (0. sativa) have prickles and microhairs only. The apices of awns generally vary from smooth (with reduced rounded 

to truncate swellings) to covered with projecting prickles. 

EMBRYO 

Tateoka (1964) investigated the embryo structure of species 

of Oryza and recognized three types in cross section. In type 1 

the epiblast is fused with the lateral parts of the scutellum, and 

only the uppermost part is free from attachment. This type also 

has auricles between the epiblast and the coleoptile. Tateoka included all of the species of the 0. sativa group (0. barthii, 0. 

glaberrima, 0. longistaminata, 0. rujipogon, and 0. sativa) in 

type 1. In type 2 there is no auricle and the epiblast is seen as 

distinct. This type includes 0. brachyantha, 0. meyeriana, and 

0. ridleyi. In type 3 there is a cleft between the scutellum and 

coleorhiza, an auricle is lacking, and the epiblast is very long 
6 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

and separate from the scutellum. This type is found only in 

Porteresia coarctata, a genus closely related to Oryza. 

PEDICELS AND CUPULES 

The apices of Oryza pedicels are expanded to form cupules 

that are often bilobed (Figures 2c, 12b). The structure of these 

lobed cupules in Oryza drew the attention of the eminent agrostologist Otto Stapf, who believed them to be glumes. The opposing concept considers the glumes to be the distinct paired 

structures, in the past called sterile or empty lemmas, located 

above the articulation point and closely resembling the conventional glumes of other grasses. 

J.D. Hooker (“Hook.f.”), contributor of Gramineae to the 

Flora of British India (1 896), described the pedicels of Oryza as 

being annular (ring-shaped) at the apex, and “Glumes I and 11” 

as being what have since been called the sterile lemmas; thus, 

Hooker originally had a conventional concept of the glumes. 

Hooker (1900: 182) later contributed the Gramineae for Trimen’s work on the flora of Ceylon, but in this case he provided 

data from Stapf, as follows: “Dr. Stapf, who has made a careful 

study of the morphology of the spikelets of Oryza, informs me 

that it consists theoretically or normally of 5 glumes, of which 

the two lowest are very minute, are confluent with the tip of the 

pedicel, and rarely discernible. The spikelet is hence only apparently articulate with the pedicel, the real articulation being 

above these two suppressed glumes. The two following glumes, 

also empty, are always minute, and one, or rarely both, are 

sometimes suppressed.” During the same year Stapf (1900) contributed the Gramineae to the Flora Capensis. Oryza is absent 

from the Cape region, but Stapf (1900:659) described the 

closely related genus Leersia as having “glumes reduced to an 

obscure hyaline entire or 2-lobed rim.” Stapf (19 17:22) stated 

the following in the tribal and generic key to Oryzeae and Oryza 

in the Flora of Tropical Africa (the Gramineae were never completed beyond genus 101; Oryza was genus 147): “Glumes very 

minute or confluent into an annular rim or suppressed.” 

Subsequently, authors have variously accepted or rejected 

Stapf’s concept of the glumes in Oryza. Weatherwax 

(1929:548), in a detailed study of the spikelets of the Oryzeae, 

considered the glumes of Oryza to be the conventional, glumelike, sterile lemmas. He believed that the lobed sides of the end 

of the pedicel “possibly represent bractlets, and they are sometimes sufficiently elongated to be mistaken for glumes. The 

true glumes are above the articulation.” Santos (1 933) provided 

a detailed study of the morphology of 0. sativa and had a concept like that of Weatherwax. 

The most influential proponent of Stapf‘s concept was the 

eminent botanist Agnes Arber. In her book (Arber, 1934) she 

diagrammed a cross section of a spikelet of 0. sativa and 

claimed that Stapf‘s concept was correct. She incorrectly cited 

Stapf‘s contribution as the Flora of Tropical Africa in 1898, a 

listing that has confused a number of later authors. Another influential botanist, the Kew agrostologist C.E. Hubbard (1934), 

accepted Stapf‘s interpretation of the structure of the glumes 

and sterile lemmas. He described the spikelets of 0. australiensis as having glumes larger and more distinct than any other 

species of Oryza. His measurements showed the glumes to be 

0.5 to 0.8 mm long, whereas the sterile lemmas were 1.5 to 2.5 

mm long. 

Michaud (1944) described abnormalities in the spikelets of 

0. sativa resulting in duplication of fertile lemmas and loss of 

sterile lemmas. These abnormalities bear mainly on the problem of the origin of the lemma and palea and are open to alternative interpretations. 

Backer (1946) opposed Stapf‘s theory by claiming that the 

pedicel cupules were nothing more than the expanded ends of 

the pedicel. He pointed out the existence of an andropogonaceous grass, Asthenochloa Buse, that has a cup-shaped terminus on each branch, with a structure similar to that of species of 

Oryza. Backer (1946) mentioned other grasses with cup-shaped 

pedicel tips: Rhynchelytrum Nees (Paniceae), Garnotia 

Brongn. (Arundinelleae), and Cyathopus Stapf (Aveneae). 

Chatterjee (1948), on the other hand, reviewed the previous 

literature and accepted Stapf‘s concept as correct. De Winter 

(1 95 1) in treating the oryzaceous genus Potamophila R. Br. 

also accepted Stapf‘s concept. In the South African species I! 

prehensilis (Nees) Benth., De Winter described reduced glumes 

forming a small entire or bilobed hyaline cup. Schweickerdt 

and Marais (I 956) presented an extensive study of abnormal 

spikelets in 0. barthii, including abnormalities in the pedicel 

apices as well as in the spikelets. Like the work of Michaud 

(1944), this study of abnormalities is subject to more than one 

interpretation and involves the origin of the oryzal lemma and 

palea. Pyrah (1 969), in a revision of Leersia, tentatively accepted Stapf’s concept, but stated that more evidence was 

needed. 

In connection with aberrant spikelets, we call attention to 0. 

grandiglumis (Figure 14), a South American species having 

two extra bracts below the lemma and palea and lacking “sterile lemmas.” The two extra bracts bear tubercles, so they are 

considered to be extra lemmas. This species needs further 

study. 

Our study of three species (0. sativa, 0. grandiglumis, and 

0. meyeriana) shows that the epidermal features present on 

their pedicels and cupules are microhairs, prickles, silica bodies, stomata, and papillae (Figures 2, 12). The relative abundance of a particular epidermal feature may vary locally; thus, 

the sides of cupules may have aggregations of microhairs (Figure 2). The cupules and their pedicels possess essentially the 

same features and differ only in the relative abundance of features. End views of the cupules show a thin cup of tissue surrounding, but free from, a central cylinder of vascular tissue 

(Figure 12b). Because the vascular cylinder is free from the 

surrounding cupule and prior to abscission passes upward into 

the spikelet, we conclude that the cupule, whether lobed or not, 

may function only as part of the support for the spikelet. We 

suspect that there are no separate, small, vascular bundles in 

the cupule. The diagram of Arber (1934: 185, fig. 88, D2) designates the outer empty glume 1 (one of the two cupule lobes) 
NUMBER 91 

as “non-vascular except for small bundle at side of base.” It is 

difficult, however, to see where this bundle is located in the diagram. It is clear, however, that each sterile lemma has one vascular bundle. 

We also examined the cupules of 0. australiensis and found 

them to be slightly larger than in other species (as noted by 

Hubbard, 1934) and bent or somewhat reflexed. We consider 

this a difference in degree, which does not change our conclusions based on other data. 

In previous investigations of the spikelets in Leersia (Terrell 

et al., 1983), the expanded end of the pedicel was considered as 

merely a cup-shaped pedicel apex. Recent examinations (in 

1998) of several species of Leersia show that the cupules are 

often about 0.15 to 0.3 mm wide, with rims rounded or truncate, and sometimes slightly undulate. Leersia lenticularis 

Michx. cupules are more flattened and expanded and are obscurely bilobed. Other observations show that Leersia cupules 

are like those of Oryza, where the surrounding cupule is free 

from the central vascular cylinder. Leersia lacks sterile lemmas 

(true glumes). We found minute knobs on the calluses of the 

spikelet in Leersia as well; whether these are rudimentary remnants of the glumes remains to be determined. In the oryzaceous genus, Zizania L., glumes are lacking, and the cupules of 

the pedicels are conspicuously expanded, unlobed, and larger 

than in Oryza and Leersia. In the pistillate branches the pedicel 

apices are as wide as 1.2 mm (Terrell et al., 1997). Expanded 

cupules are known to occur in other grass tribes, as noted by 

Backer (1 946, see above). 

The following four points summarize our view of the nature 

of glumes in the Oryzeae: (1) the pedicel and its cupule are below the point of articulation of the spikelet and are therefore 

not part of the spikelet at all; (2) the pedicels and their cupules 

have the same kinds of epidermal features, and the cupules are 

not sufficiently differentiated from the contiguous pedicels to 

be a distinct structural entity; (3) the cupules, whether lobed or 

not, are free from the vascular cylinder that proceeds upward 

(distally) into the spikelet, and therefore serve only as part of 

the support of the spikelet; (4) Leersia, Zizania, and Potamophifa (de Winter, 195 1) also have expanded pedicel apices, although rarely lobed. If cupules are sometimes lobed, this suggests to us that they are simply following the basic tendency of 

stems/pedicels to branch dichotomously. We therefore conclude that in Oryza the pedicel cupules are not glumes but are 

merely the expanded apices of the pedicels, and all subsequent 

references to glumes are based on these conclusions. 

Comparative Morphology of Species of Oryza and 

Related Genera 

The Oryza sativa group includes about 13 species native to 

Asia, Africa, Australia, or South America. The main part of the 

0. sativa group includes the type species, 0. sativa, which is 

also the best-known species because of its worldwide cultivation as one of the three most important crops. We recognize 

four other species in this main part, 0. barthii, 0. glaberrima, 

0. longistaminata, and 0. rufipogon. Oryza barthii includes 0. 

breviligulata A. Chev. & Roehr. (Clayton, 1968) and 0. stapfii 

Roshev. (Tateoka, 1963). As noted by Vaughan (1989), the taxonomic relationships among these species need further study. 

The epidermal features and spikelet structure of 0. sativa are 

illustrated in Figures 1-7, and the remaining four species of 

this group are illustrated in Figures 8-1 1. The five species have 

a general basic morphology that provides a standard of comparison for the remaining species of the genus. They have the 

0. sativa type of spikelets showing a characteristic array of 

characters: large globose rachillas bearing muricate projections; furrowed lemmas and paleas with 1- to 4-pronged tubercles arranged in an orderly pattern of tiers and rows on the 

ridges of the lemmas; lateral articulation points (scars); lanceolate glumes; and type 1 embryos, as recognized by Tateoka 

(1 964). 

The second part of the 0. sativa group is designated as the 0. 

latifolia group, and includes 0. alta, 0. australiensis, 0. eichingeri, 0. grandiglumis, 0. latifolia, 0. minuta, 0. officinalis, 

and 0. punctata (Figures 12-1 5). Tateoka (1 962a,b, 1964, 

1965a,b) intensively investigated this group. The African species, 0. eichingeri, was not included in our study, but it is 

clearly closely related to 0. punctata and 0. officinalis 

(Tateoka, 1965). Oryza officinalis was included in our study, 

although it is sometimes placed in synonymy under 0. minuta 

(Duistermaat, 1987). Oryza australiensis appears to belong to 

this group because it has similar morphological characteristics. 

The 0. latifolia group is generally very similar to the main 

part of the 0. sativa group in the features of the lemma and 

other spikelet parts and differs only in having the following 

characteristics: (1) although muricate, the rachillas are small to 

rudimentary compared to the large globose ones in the 0. sativa group; (2) the point of articulation is horizontal or slightly 

oblique and the glumes are more or less opposite each other; 

and (3) the apicular knobs are absent or rudimentary. 

Oryza meyeriana (Figures 16-18) was placed in section 

Granulatae by Roshevitz (1 93 l), but this has been superseded 

by the earlier section Padia. Sectional ranking appears fully 

justified because of the distinctive morphological differences. 

Oryza meyeriana includes two varieties (Duistermaat, 1987), 

var. meyeriana (from Malesia) and var. granulata (from India, 

Thailand, Malesia, Southeast Asia). Duistermaat (1 987) distinguished these varieties by the lengthlwidth ratios of the spikelets and caryopsis size. Tateoka (1962b) treated these as subspecies and also recognized 0. meyeriana subsp. abromeitiana 

(Prod.) Tateoka, treated by Duistermaat (1987) as a synonym of 

0. meyeriana var. meyeriana. 

Our sampling of this taxon includes two collections of each 

variety (Figures 16-18) and a fifth collection, which appears to 

be intermediate between the two varieties. The collections of 

0. meyeriana var. meyeriana have thick, indurate rachillas, 

whereas the collections of 0. meyeriana var. granulata have 

non-indurate rachillas that appear wrinkled and somewhat 
8 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

compressed. These characters were not described by Duistermaat, and whether the presence or absence of indurate rachilla 

bases has taxonomic significance is a question beyond the 

scope of this paper. 

The most conspicuous feature of the lemmas of 0. meyeriana is the presence (in both varieties) of numerous complex tubercles centered over the furrows (Figures 16, 18). These tubercles are complex in having a sharply pointed, sometimes 

oblique or bent spine or prong, completely fused with the 

densely papillate or tuberculate adjacent base tissue. The tubercles are fused from one furrow to the next. The over-furrow position of the central spine suggests that a well-developed 

prickle forms the central part of the complex tubercles. These 

tubercles differ from those of the Otyza sativa group in having 

an over-furrow position and a more complex fused structure. 

They render the lemma of 0. meyeriana (especially 0. rneyeriana var. granulosa) even more spiny than the lemmas of the 0. 

sativa group. 

Oryza meyeriana is characterized by glumes that are linear 

or subulate and only slightly longer than the rachilla (Figures 

16, 17). Also, the glumes are somewhat offset from each other. 

Below the glumes is the base, including the callus, that bears 

stomata. Above the glumes are the short, broad, indurate or 

wrinkled rachillas bearing rounded silica bodies. The lemma 

and narrower palea lack awns and have merely short obtusely 

pointed apices that seem to lack apicular knobs. 

In summary, the spikelets of 0. meyeriana differ strongly 

from those of the Otyza sativa group as follows: (1) glumes are 

short and linear or subulate, not lanceolate; (2) the rachillas are 

not muricate and bear silica bodies; (3) the tubercles are positioned over the furrows instead of between the furrows; (4) the 

tubercles are larger and more complexly fused; (5) lemma apices lack apicular knobs; (6) the lemma and palea lack awns; 

and (7) the shape of the spikelet is more or less elliptical, with a 

blunt apex, which is quite unlike that of the 0. sativa group. 

Oryza ridleyi (Figures 19, 20) is native to Southeast Asia, 

Malesia, and New Guinea (Duistermaat, 1987). Oryza longiglumis Jansen (from Papua New Guinea) was not included in 

our study because of its similarity and close relationship to 0. 

ridleyi. The shape of the spikelets in 0. ridleyi is somewhat 

similar to that of the Otyza sativa group and differs from the elliptical spikelets in 0. meyeriana. Oryza ridleyi lemmas also 

have conspicuous awns (Figure 19), whereas 0. meyerianu has 

none. The linear or subulate glumes are somewhat offset from 

each other (Figure 19) and are unequal in length, with the 

longer one being as much as four-fifths as long as the spikelet. 

This species and 0. longiglumis have the longest glumes in the 

genus (except possibly for 0. sativa cultivated varieties and 0. 

glaberrima). Above the glumes is a subcylindrical and indurate 

rachilla sometimes thickly beset with silica bodies. One sample 

of this species had an attached pedicel with a bilobed cupule, as 

is typical of other species of Otyza. 

The lemma and somewhat narrower palea are beset with tubercles (Figure 20), which, like those of 0. meyeriana, are positioned over the furrows. The tubercles differ, however, from 

those of 0. meyeriana because they are simple and not complex. Prickles in rows also may occur on the lemmas and paleas 

and sometimes are modified to resemble the tubercles. Some of 

the papillae on the long cells may be enlarged and have apical 

pores (Figure 20b). The lemma and palea margins in our samples are ciliate with stiff prickles. The lemmas end in an awn, 

and the palea has only a short, awn-like point. The awn bases 

and palea tip bear prickles, stomata, and microhairs, but the 

ends of awns are so thickly beset with prickles that little else is 

visible. 

Tateoka (1 964) found that both 0. meyeriana and 0. ridleyi 

have type 2 embryos, but the several differences noted herein 

outweigh these similarities between the two species. Roshevitz 

(1 93 1) placed 0. ridleyi with 0. coarctata Roxb., 0. brachyantha, and 0. fongigfurnis. Tateoka (1 964) and subsequent authors have accepted the recognition of 0. coarctata as a distinct 

genus, Porteresia. Tateoka (1 964) placed 0. ridleyi, 0. brachyantha, and 0. longiglumis in a new section, Ridleyianae. 

Otyza brachyantha (Figures 2 1, 22) is native to West Africa, 

Congo, Sudan, and Zambia (Clayton, 1968). It has narrow 

spikelets with very long (to 17 cm) awns that differ from conventional awns in having two groups of xylem instead of one 

(Roy, 1968). The stipitate callus is very large, indurate, and homogeneous and is hsed with the glume bases and extends from 

the spikelet base to the lemma base (Figure 21a). Its surface 

has silica bodies. The glumes are strongly offset from each 

other, one arising near the spikelet base, the other from the upper part of the callus. Just below the second glume is a lateral 

articulation point. A rachilla is lacking. The glumes are linear, 

quite unequal in length, and less than one-half as long as the 

lemma. Our samples did not have any conspicuous epidermal 

features. The lemma is much wider than the linear palea, lacks 

tubercles, and has microhairs, prickle hairs, and sometimes numerous papillae. There are large apicular knobs. 

Although Tateoka (1964) included 0. brachyantha with 0. 

ridleyi in section Ridleyianae. comparison of 0. brachyantha 

with other species of the genus show the following important 

characteristics: (1) strongly offset glumes; (2) very large, stipitate callus; (3) lemmas that lack tubercles, (4) absence of a 

rachilla; and (5) the presence of very long awns. These characteristics distinguish 0. brachyantha as forming a distinct subgenus in Oryza. The resemblance and relationships of 0. 

brachyantha and Leersia nematostachya are discussed under 

the latter taxon. 

Oryza schlechteri (Figure 23) is native to northeastern New 

Guinea. The species is rare and is represented by very few herbarium specimens (Vaughan, 1989). It is a tufted perennial less 

than one meter tall, with a short panicle and muticous spikelets 

only about 1.75 to 2.15 mm long (Duistermaat, 1987; Vaughan, 

1989). The base of the spikelet is small, fused with the glumes, 

and bears silica bodies. The two glumes (sometimes only one) 

are subopposite, lanceolate, short, unequal, and bear papillae, 

prickles, and silica bodies. A rachilla is lacking. The palea is 

much smaller than'the lemma but is similar to it in texture. The 

distal half of the lemma has conspicuous furrows with microhairs and prickles (along the distal midnerve) but lacks silica 

bodies or tubercles. The basal one-fourth to one-half of the 
NUMBER 91 9 

lemma lacks furrows, is entirely smooth, and bears conspicuous silica bodies. The apices of the lemma and palea are obtuse, and with coalesced stomata, microhairs, and reduced 

prickles. Apicular knobs and awns are lacking. The small ovate 

spikelets of 0. schlechteri resemble those of Leersia in their 

shape and small size but differ in having a pair of glumes. Species of Leersia, besides lacking glumes, have lemmas with siliceous triads consisting of a central silica body flanked by a tubercle on each side (Terrell et al., 1983). One species, Leersia 

lenticularis Michx., has silica bodies but lacks lateral tubercles; 

in all other characters it is typical of Leersia. In 0. schlechteri 

the “upper” (distal) furrowed parts of the lemma entirely lack 

silica bodies and tubercles, but the more basal smooth parts of 

the lemma have silica bodies without accompanying tubercles 

(Figure 23c). Thus, the lemma of 0. schlechteri exhibits characters of both Leersia and Oryza. 

After comparing 0. schlechteri to species of Leersia and 

Oryza, Naredo et al. (1 993) concluded that the presence of a 

glume (their material had only one) and the absence of triads 

on the lemma indicated that the species belonged in Oryza. We 

agree with this conclusion, although we point out the occurrence of silica bodies on the basal parts of the lemma in 0. 

schlechteri. 

Oryza schlechteri may represent an evolutionary stage somewhat intermediate between Leersia and Oryza, but with a preponderance of Oryza characters. We suggest its placement in a 

distinct subgenus of Oryza. 

Porteresia is a monotypic genus and is represented by Porteresia coarctata, a species native to southern Asia. Porteresia coarctata, originally described as an Oryza. was shown by 

Tateoka (1964, 196%) to be distinct from Oryza in having a 

large caryopsis with a bent apex, a large embryo, and short, petiolar, basal attachments. He described unusual characters in the 

leaf blades, such as the occurrence of two superposed bundles 

in each rib, air spaces within the mesophyll, and papillae with 

bifurcate tips (see also Clayton and Renvoize, 1986). Cope 

(1982) described I? coarctata as having extensive rhizomes and 

culms to two meters tall. He also noted that it forms dense mats 

at the mouth of the tidal Indus River in Pakistan and that it also 

occurs in India and Burma. Other authors have provided additional general data for this unique taxon (Dikshit et al., 1993). 

The spikelets (Figures 24, 25) are narrowly oblong to narrowly ovate, 12 to 15 mm long (including the awn), and obliquely articulated with the pedicel. Our observations indicated 

that the unique callus is expanded as a rigid, transversely narrowed disk bearing silica bodies. The glumes are somewhat 

offset, linear, subequal, one-third as long as the spikelet, and 

lack apparent epidermal features. A rachilla is lacking. The 

lemma has a thin, wing-like portion. The palea is linear and almost as long as the lemma. The lemma has prominent long 

cells and lacks furrows. Tubercles also are lacking, but the 

lemma has small microhairs, stomata, and papillae. The lemma 

apex bears a rigid awn about 4 mm long, with microhairs and 

stomata. Apicular knobs are lacking. These distinctive spikelet 

features, along with other unique characteristics, lend support 

to recognition of this taxon as a separate genus. 

Rhynchoryza is a monotypic genus that is represented by R. 

subulata. The species (Figures 26, 27) is native to Argentina, 

Brazil, Paraguay, and Uruguay. Its spikelets have several morphological features that set it apart from the Oryza species. The 

large spikelets are long and narrow, about 3.5 to 5 cm long, including the long awns. The base below the glumes has a solid, 

rounded, small callus bearing silica bodies. There is a horizontal or slightly oblique articulation point. The glumes (only 1 to 

3 mm long) are opposite, somewhat ovate, and with two to a 

few acutely pointed lobes with conspicuously large marginal 

prickle hairs. The surface of the glumes has microhairs, papillae, and silica bodies. A rachilla is lacking. The lemma and 

palea are markedly unequal in size and shape. The palea is linear, shorter than the lemma, and with smaller tubercles. The 

long, narrow lemma has two sections. The basal half is coriaceous and lacks furrows, but it bears rows of rounded mammiform tubercles with pointed, withered apices. Also present are 

few and scattered microhairs and prickle hairs, along with papillae. The distal half of the lemma is chartaceous or somewhat 

soft and lacks tubercles but has microhairs, papillae, prickles, 

silica bodies, and unusual stomata conspicuously bordered by 

four papillae (Figure 27). The lemma tapers gradually into an 

awn (-2.5 cm long) bearing microhairs and prickles. Apicular 

knobs are lacking. Clayton and Renvoize (1986:72) described 

the distal section of the lemma as a “conical herbaceous beak 

composed of aerenchyma with transverse septa.” This constituted a “flotation device built into the spikelet.” Rhynchoryza 

subulata is so distinctive in relation to other species of Oryza 

that no one is likely to question its generic status. 

Launert (1 965) surveyed the African species of Leersia and 

noted that three of the species were difficult to assign to either 

Leersia or Oryza. These were Leersia perrieri (A. Camus) 

Launert, L. tisserantii (A. Chev.) Launert, and L. nematostachya Launert (formerly L. angustifolia C.E. Hubb.). The 

first two of these were found later to have siliceous triads like 

all other species of Leersia and were similar in other characteristics with Leersia (Terrell et al., 1983). The third species, however, lacks siliceous triads. 

Hubbard (1 95 1) and Launert (1 965) noted the resemblance 

between Leersia nematostachya and Oryza brachyantha. Both 

species have very long slender awns (to 18 cm) and narrow 

spikelets with large indurate stipitate calluses (bearing numerous silica bodies) extending from the base of the spikelet to the 

base of the lemma. We contrasted other characters in this species with those of 0. brachyantha. Laersia nematostachya 

grows in Zambia and Angola “in shallow laterite pans” and has 

delicate growth and convolute filiform leaves (Launert, 

1965:131); in these respects it is uncharacteristic of species of 

Oryza. Leersia nematostachya (Figures 28,29) lacks glumes, 

has silica bodies in the lemmata1 furrows, lacks apicular knobs, 

and has chartaceous, irregularly angular awns (termed pseudoawns by Launert, 197 1) with three vascular bundles. In con- 
10 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

trast, 0. brachyantha has two glumes, lemmata1 furrows lacking silica bodies, large apicular knobs, and coriaceous terete 

awns with one vascular bundle. Launert (1 965) noted that three 

nerves entered the awn in those Leersia species having awns or 

awn-like extensions, whereas in Otyza species two of the lateral nerves end in the apical region, and only one nerve enters 

the awn. In addition, Launert found that the anatomical characters of the leaves in L. nematostachya were similar to those in 

other species of Leersia. Thus, the characters of L. nematostachya are predominantly those common to other species of 

Leersia, despite some resemblance to 0. brachyantha. Within 

Leersia the closest relatives to L. nematostachya are L. perrieri 

and L. tisserantii. 

Numerical Analyses 

CHARACTERS AND THEIR STATES.-l. Spikelet articulation 

position: 1 =horizontal or slightly oblique; 2=lateral. The 

point of articulation is located just below the glumes. In the lateral state (2) the articulation point is off to one side but still below the upper glume. 

2. Callus shape: 1 =rounded; 2=stipitate; 3=discoid. In 

Oryza the callus extends from the point of articulation of the 

spikelets to the base of the first and second glume, sometimes 

fused with the glume bases. At the base of the spikelet the 

small and rounded shape (1) is common in the 0. Iatifolia 

group. In 0. brachyantha and Leersia nematostachya the stipitate callus (2) forms a solid, indurate, homogeneous structure 

extending from the spikelet base to the base of the lemma. The 

callus here is extended and massive. The discoid callus (3) is a 

laterally expanded disk found only in Porteresia. 

1 =opposite; 2=slightly or somewhat 

offset (alternate); 3=strongly offset. In state three the glumes 

are separated by a considerable distance seen only in 0. 

brachyantha. Although somewhat subjective, position of the 

glumes is consistent and useful in separating the species. 

1 =linear or subulate; 2=lanceolate or 

narrowly lanceolate; 3=irregularly hastate or broadly ovate. 

State two is defined herein as widest near the base. 

1 =present; 2=absent. The Oryza type of 

rachilla is of three types (see character 6) and not slender, filiform, pedicel-like, or stipoid as in most other grasses. The 

presence of a rachilla is found in members of subg. Oryza. 

1 =subglobose (large, 0.5-2 mm long); 

2=subglobose/rudimentary (small, 0.1-0.4 mm long); 3=cylindrical or broadly cylindrical. The 0. sativa group is characterized by a large subglobose rachilla (1) whereas the 0. latifolia group has a smaller subglobose/rudimentary rachilla (2). In 

0. ridleyi and 0. meyeriana the rachilla is elongated, either cylindrical or broadly cylindrical (3). This character is inapplicable in 0. brachyantha, 0. schlechteri, and all outgroups because a rachilla is absent. 

7. Rachilla muricate: 1 =present; 2=absent. These small, 

numerous projections are pointed, rounded or somewhat obtuse 

3. Glume position: 

4. Glume shape: 

5. Rachilla: 

6. Rachilla shape; 

and are considerably smaller than lemma tubercles. Tubercles 

are larger and more prominent on the lemma and palea. The 

presence of a muricate rachilla is seen only in sect. Oryza. 

1 =present; 2=absent; 3=absent only 

on the basal portion. Lemma furrows are folds in the epidermis/cuticle that run parallel with the keel and veins. Character 

state three is retained here to emphasize the unique feature of 

0. schlechteri where the furrows are absent on the basal onefourth to one-half of the lemma. 

1 =present; 2=absent. These irregularly shaped structures have been found to contain high levels 

of silica. The tubercles are arranged in distinct rows in four 

major shapes (see character 10). This is an important character 

found in all members of subg. Oryza. 

1 = 1 - to 4-pronged on ridges; 2 

= 1 -pronged on furrows; 3 =complex on furrows; 4=scattered 

mammiform. A pronged tubercle comes to a point above the 

surface; they can have up to four prongs. The important distinction is whether these tubercles are arranged on a ridge or a furrow. Complex tubercles are found in 0. meyeriana where the 

tubercles are fused over the furrow. Mammiform tubercles are 

found in Rhynchoryza. This character is inapplicable in 0. 

brachyantha, 0. schlechteri, Porteresia coarctata, and Leersia 

nematostachya because tubercles are absent. 

I =present on lower three-fourths; 

2=absent on lower three-fourths. These siliceous structures are 

firmly embedded in the epidermis and vary in shape from being 

2- to 4-lobed to almost entire or with irregular sinuses. 

l=present; 2=absent. Porteresia and Rhynchoryza are the only taxa that have 

stomata. Therefore, this character is of little value. 

l=present; 2=absent. Lemma awns are 

absent in 0. meyeriana and 0. schlechteri. 

l=type 1; 2=type 2; 3=type 3. In type 1 

the epiblast is fused with the lateral parts of the scutellum and 

only the uppermost part is free from attachment with auricles 

between the epiblast and the coleoptile. In type 2 there is no auricle and the epiblast is seen as distinct. In type 3 there is a cleft 

between the scutellum and coleorhiza, no auricle, and the epiblast is very long and separate from the scutellum. This latter 

type is found only in the outgroup Porteresia coarctata. This 

character is undetermined for 0. schlechteri and Leersia nematostachya . 

UPGMA ANALYSIS.-using the 14 morphological characters above as scored in Table 2, six (A-F) major groups in 

Oryza are shown in the phenogram (Figure 30). These are as 

follows: (A) 0. sativa, 0. barthii, 0. glaberrima, 0. longistaminata, 0. rufipogon; (B) 0. alta, 0. australiensis, 0. grandiglumis, 0. latifolia, 0. minuta, 0. officinalis, 0. punctata; 

(C) 0. meyeriana var. meyeriana, 0. meyeriana var. granulata; 

(D) 0. ridleyi; (E) 0. brachyantha; (F) 0. schlechteri. Group A 

is characterized by having lateral spikelet articulation (character l), slightly or somewhat offset glumes (character 3), and 

large subglobose muricate rachillas (character 6). Groups A and 

8. Lemma furrows: 

9. Lemma tubercles: 

10. Lemma tubercle shape: 

1 1. Lemma silica bodies: 

12. Lemma body (below apex) stomata: 

13. Lemma awns: 

14. Embryo types: 
NUMBER 91 11 

B form a cluster that is supported by having muricate rachillas 

(character 7) and type 1 embryos (character 14). Group B is 

supported by having opposite glume insertion (character 3) and 

small, subglobose/rudimentary rachillas (character 6). Members of group C lack lemma awns (character 13) and share tubercle complexes on the furrows of the lemmas (character 10). 

Oryza ridleyi (D) has 1 -pronged tubercles on the furrows of the 

lemma (character 10). Groups C and D form a cluster that is 

supported by cylindrical or broadly cylindrical rachillas (character 6) and 1-pronged lemma tubercles located on the ridges 

(character 10). Species that could not be grouped or showed 

weak assemblages in the phenetic analysis were 0. brachyantha and 0. schlechteri. Oryza brachyantha (E) has a stipitate 

callus (character 2) and strongly offset glumes (character 3), 

and 0. schlechteri (F) lacks furrows on the basal portion of the 

lemma (character 8), has silica bodies on the basal three-fourths 

of the lemma (character 1 l), and lacks lemma awns (character 

13). 

PARSIMONY ANALYSIS.-A consensus tree of the 11 5 possible trees indicates that there are four clades within the species 

of Oryza that have a bootstrap value greater than 50% (Figure 

3 1). These are group A ( bootstrap value 71%, as above); group 

B (bootstrap value 54%, as above); group C (bootstrap value 

70%, as above); and group E (bootstrap value 69%), which includes 0. brachyantha and Leersia nematostachya. All other 

taxa included in this study form an unresolved network. The 

11 5 trees differ primarily in placement of 0. ridleyi-0. meyeriana, 0. schlechteri, and 0. brachyantha-Leersia nematostachya. The 17 taxa of Oryza consistently occur as a clade 

when using either Porteresia or Rhynchoryza as an outgroup 

without inclusion of Leersia. Whenever Leersia nematostachya 

is included in the analysis it forms a clade with Oryza brachyantha, thereby suggesting that Oryza is para or polyphyletic 

(see consensus tree in Figure 3 1). Most notably, Oryza brachyantha and Leersia nematostachya have a stipitate callus (character 2). This state is unique to these two taxa, whereas all others species of Oryza have a rounded callus. Leersia nematostachya lacks glumes, like other species in the genus, and has 

a pseudo-awn, unlike any species of Oryza. Because only a single species (L. nematostachya) is used to represent Leersia, and 

we are using only 14 characters, it seems a bit premature to 

place much confidence in this result. Based on our morphological observations, Leersia is the closest sister to Oryza because 

the shortest trees (21 steps) are formed when Leersia is used as 

the sole outgroup (Figure 32). The highest consistency index 

(CIzO.78) is obtained when Porteresia is the sole outgroup 

(Figure 33). 

The cladogram shown in Figure 32 was chosen to illustrate 

one possible phylogeny within the ingroup. The genus Oryza is 

characterized by a single synapomorphy: absence of silica bodies on the lower three-fourths of the lemma (character 11). In 

this cladogram Leersia does not have any apomorphies because, as discussed previously, it shares characteristics with 0. 

brachyantha, the most basal member of the Oryza clade with a 

single apomorphy of strongly offset glumes (character 3). The 

remaining species share two synapomorphies: horizontal or 

slightly oblique spikelet articulation (character 1) and a 

rounded callus (character 2) with 0. schlechteri, the sister to a 

trichotomy containing three clades (0. ridleyi, two varieties of 

0. meyeriana, and groups A and B, see consensus tree, Figure 

3 1). This trichotomy is supported by three synapomorphies: 

slightly or somewhat offset glume position (character 3), presence of an Oryza rachilla (character 5), and the presence of 

lemma tubercles (character 9). The clade containing groups A 

and B is supported by four apomorphies, of which two are nonhomoplasious: subglobose rachillas (character 6) with muricate 

projections (character 7). Group B is supported with two apomorphies: subglobose/rudimentary rachillas (character 6) and 

opposite glumes (character 3), and group A is supported by the 

reversal of character 1 (to lateral spikelet articulation). 

The cladogram rooted with Porteresia coarctata (Figure 33) 

is very similar to the one discussed in the previous paragraph 

because both share an identical trichotomy containing three 

clades (0. ridleyi, two varieties of 0. meyeriana, and groups A 

and B). In this cladogram (Figure 33) the trichotomy is supported by only two (three in Figure 32) synapomorphies: the 

presence of a rachilla (character 5) and the presence of lemma 

tubercles (character 9). Porteresia and Rhynchoryza are characterized by a single symplesiomorphy: stomata on the lemma 

body (character 12). Another trichotomy is depicted just after 

this initial node or hypothesized speciation event in Oryza 

where 0. schlechteri is supported by five apomorphies, two of 

these are non-homoplasious characters: lemma furrows absent 

only on basal portion (character 8) and lemma silica bodies 

present on the lower three-fourths (character 11); 0. brachyantha is supported by three apomorphies, two of these are nonhomoplasious characters: stipitate callus (character 2) and 

strongly offset glume position (character 3); the clade containing groups A and B is as discussed above. 

Even though our data represent only a very few characters 

and would benefit greatly from investigations on a molecular 

level, we have considered many other morphological characters for our newly hypothesized classification. The topology of 

Figure 33 closely follows our hypothesized classification 

within Oryza where we recognize three subgenera (Table 3). 

Classification of Oryza 

The earliest classifications of Oryza that created formal 

ranks were those of Baillon (1 894) and Roshevitz (193 1). The 

classification of Roshevitz was part of an intensive study of the 

morphology and taxonomy of Oryza. He recognized four sections, three of which we list in our Table 3; the fourth section 

was Coarctatae, which included primarily Oryza coarctata 

Roxb. (later removed to a separate genus as Porteresia coarctata), and secondarily 0. ridleyi, 0. brachyantha, and 0. 

schlechteri. Important additions and adjustments were made by 

Tateoka (1964) and Sharma and Shastry (1965). These classifications were discussed by others, notably by Nayar (1 973) and 
12 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

TABLE 3.-Inhgeneric classification of Ova with literature citations. 

Oryza subgenus Oryza. 

Oryza section Oryza (section Euoryza, Baillon, 1894; section Sutiva, Roshevitz, 193 1). 

Type: 0. saliva L. 

0. series Oryza [ser. Salivae Sharma & Shastry (1965)l. 

Type: 0. saliva L. 

Including 0. barthii, 0. glaberrima. 0. longistaminata, 0. rujpogon, and 0. saliva. 

0. series Latifoliae Tateoka ex Sharma & Shastry (1965) [ser. Ausrralienses Tateoka ex Sharma & 

Shastry (1965)l. 

Type: 0. Iatifolia Desv. 

Including 0. alia. 0. australiensis. 0. eichingeri, 0. grundiglumis, 0. latifolia, 0. minula, 0. oflci0. section Padia (Zoll. & Moritzi) Baill. (1894), based on Padiu Zoll. & Moritzi, Syst. Verz. Zoll. 103 

nalis. 0. punciata. 

(1846); sect. Granufatae Roshev. (193 I); ser. Meyerianae Sharma & Shastry 1965. 

Type: 0. meyeriana (Zoll. & Moritzi) Baill. 

Including 0. meyeriana var. meyeriana, 0. meyeriana var. grunula1u. and 0. meyeriana var. abromeitiuna. 

0. section Ridleyanae Tateoka (1964) [ser. Ridleyanae Sharma & Shastry (1965)l. 

Type: 0. ridleyi Ho0k.f. 

Including 0. ridleyi and 0. longiglumis. 

0. subgenus Brachyanthu (Sharma & Shastry) Terrell, P.M. Peterson, & Wergin [based on 0. ser. Brachyanthae 

S. Sampath ex Sharma & Shastry (1965)l. 

Type: 0. brachyanthu A. Chev. & Roehr. 

0. subgenus Schlechteria (Sharma & Shastry) Zxrell, P.M. Peterson, & Wergin [based on 0. ser. Schfechterianae 

Sharma & Shastry (1965)l. 

Type: 0. schlechteri Pilg. 

Tucker (1 988). We also consulted Yaughan’s (1989) extensive 

review of Oryza. In Table 3 we present further adjustments in 

classification, primarily on the basis of spikelet characters 

(which are fundamental reproductive characters). We recognize 

0. ridleyi as a distinct section, and 0. brachyantha and 0. 

schlechteri as separate subgenera (spellings of subgeneric 

names follows Greuter et al. (1994), particularly Articles 21 

and 22). The other three genera examined herein are distinct 

Oryza subg. Brachyantha (S. Sampath ex Sharma & Shastry) 

Terrell, P.M. Peterson, & Wergin, comb. et stat. nov. Basionym: 

0. ser. Brachyanthae Sharma & Shastry, Indian J. Genet. P1. 

Breed. 25:175. 1965.-Type: Oqza brachyantha A. Chev. & 

Roehr. 

Oryza subg. Schlechteria (Sharma & Shastry) Terrell, P.M. 

Peterson, & Wergin, comb. et stat. nov. Basionym: 0. ser. 

Schlechterianae Sharma & Shastry, Indian J. Genet. P1. Breed. 

genera and need no further reclassification. 25: 174. 1965.-Type: Oryza schlechteri Pilg. 
Appendix 

Descriptions of Species Groups of Oiyza 

Oryza sect. Sutiva ser. Sutiva.-Spikelet with articulation point 

lateral; callus rounded at base, fused with glume bases; 

glumes slightly or somewhat offset, subequal, lanceolate 

or lance-ovate, extending to middle of lemma or rarely to 

top of lemma, lacking epidermal features or sometimes 

bearing prickles or silica bodies; rachillas large, subglobose, located above (distal to) both glumes, covered with 

muricate projections visible macroscopically, sometimes 

with microhairs, prickles; lemmas furrowed, tubercles 

large, with 1 to 4 sharp points, located on the ridges, with 

appressed microhairs and prickles in the furrows, papillae 

common; palea similar to lemma, narrower; lemma and 

palea apices with tubercles, microhairs, prickles, papillae; 

apicular knobs conspicuous at lemma tip; awns present or 

absent, with microhairs, prickles. 

Oryza ser. Latifoiiae.-Spikelet with articulation point horizontal or slightly oblique; callus small or somewhat larger, 

sometimes hardly visible below glume bases, flattish or 

rounded at base, horizontal or oblique, fused with glume 

bases; glumes appearing opposite, subequal, lanceolate or 

lance-ovate, very short to one-fourth or one-third as long 

as lemma, lacking epidermal features or sometimes bearing microhairs, prickles, papillae, silica bodies; rachillas 

small or rudimentary, a triangular area or barely discernible, located above (distal to) both glumes, covered with 

muricate projections visible macroscopically; lemmas furrowed, tubercles large, with l to 4 sharp points, located on 

the ridges, with appressed microhairs and prickles in the 

furrows, papillae common; palea similar to lemma, narrower; lemma and palea apices with tubercles, microhairs, 

prickles, papillae; apicular knobs none; awns present, with 

microhairs, prickles, silica bodies. 

Oryzu sect. Pudiu.-Spikelet obtuse or blunt; articulation point 

horizontal or slightly oblique; callus short, broad, fused 

with glume bases, bearing silica bodies and stomata; 

glumes slightly or somewhat offset, subequal, short, linear 

or subulate, with microhairs, prickles, silica bodies; rachillas cylindrical or broadly cylindrical, indurate or wrinkled, 

fused below with the glume bases; lemmas furrowed, tubercles large, complex, fused with prickles and papillae, 

on the furrows, usually with one short sharp point, with 

microhairs, prickles, papillae, tubercles smaller in 0. meyeriana var. meyeriana; palea similar to lemma, narrower; 

lemma and palea apices with microhairs, stomata, prickles, 

papillae; apicular knobs none; awns none. 

Oryza sect. RidIeyanue.-Spikelet with articulation point horizontal or slightly oblique; callus small, indurate, fused 

with glume bases; glumes slightly or somewhat offset, 

quite unequal, extending past mid-lemma, linear or subulate, with microhairs, prickles, silica bodies; rachillas cylindrical, fused below with glume bases; lemmas furrowed 

with 1 -pronged tubercles on the furrows, with sharp or obtuse apices, microhairs, prickles, papillae numerous; 

lemma and palea apices with microhairs, prickles, stomata; 

palea as for lemma; apicular knobs none; awns with microhairs, prickles, stomata. 

Oryza subg. Brachyantha.-Spikelet narrowly oblong; articulation point lateral; stipitate callus long and wide, extending to base of lemma, indurate, fused with glume bases, 

with silica bodies; glumes strongly offset, unequal, less 

than one-half as long as lemma, linear, lacking epidermal 

features; rachillas absent; lemma much wider than palea; 

lemma furrowed, lacking tubercles, with microhairs, 

prickles in furrows or prickles grouped in lines, with or 

without papillae; palea linear, muticous; lemma and palea 

apices with microhairs, prickles, papillae, some coalescence; apicular knobs large; awns very long, to 17 cm, 

with microhairs, prickles. 

Oryza subg. Schfechteria.-Spikelet small, resembling Leersia 

spikelets in shape and size; articulation point horizontal or 

slightly oblique; callus very small, fused with glume bases, 

with silica bodies; glumes two, or sometimes only one, appearing opposite, unequal, small, shortly lanceolate, bearing silica bodies, prickles, papillae; rachillas absent; lemmas with distal section (two-thirds more or less of lemma) 

with conspicuous furrows, lacking tubercles, with microhairs, prickles, papillae; basal section of lemmas more or 

less smooth, lacking furrows, with conspicuous silica bodies; lemma and palea apices obtuse, with coalesced stomata, microhairs, reduced prickles; palea much narrower 

than lemma; more or less similar to lemma in epidermal 

features; apicular knobs none; awns none. 

13 

Figures 
16 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 1 .-Spikelets of Otym .saliva (a,h Walkins s. n., I7 Oct 1945, Upper Burma (US-2 I1 5904); c,d, Chase 

8550. 20 Feb 1925, Brazil (US-1257171)): u and dwith pedicels removed; b with glumes scarcely visible. (Scale 

=I mm.) 
NUMBER 91 

FIGURE 2.-Bilobed cupule and pedicel of Oryza sativa (P.I. 3732 10): a, cupule with microhairs, papillae; glume 

above left and globose rachilla to upper left; b. pedicel with large prickle, microhair, stomata, papillae; c, base of 

cupule with microhairs and silica bodies; d, cupule with microhairs and stomata. (MT=turgid microhairs; PA= 

papilla; S=stomate.) 

17 
18 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 3.-Spikelets of Oryza saliva (a,c. P.I. 391823; b,d, P.I. 373210): a, lower part of spikelet showing 

cupule, glumes (offset), globose rachilla, base of lemma, and palea; b, glume with lobed silica bodies; c, globose 

muricate rachilla; d, same, projections enlarged. (B=silica body; G=glume; R=rachilla.) 
NUMBER 91 

FIGURE 4.--Lemmas ofOtyzu.rurivu (u.c. P.I. 391823; b, cv. Strawhull Red; d, P.1. 373210): cr, lemma (left) and 

palea with vertical tiers and horizontal rows of tubercles, scattered prickles; kf, tubercles enlarged, microhairs 

in furrows. (M =microhair; P=prickles; T=tubercles.) 

19 
20 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 5.-Lemmas of Oryu sativa cv. Saturn by EDX analysis: a-c. line scan shows high silicon content in 

tubercles, low content in microhairs and furrows; d. X-ray mapping shows silicon in tubercles. 
NUMBER 91 

FIGURE 6.-Apices of spikelets of Oryza sativa (a, cv. Nortai; b, P.I. 391 823; c.d, P.I. 160978): a, lemma apex with 

apicular knob opposite to palea apex; 6, detail of lemma apex and apicular knob; c, same with microhairs, papillae, 

and prickles; d. same, enlarged, showing indurate fused base of a prickle. (A=apicular knob; P=prickles.) 

21 
22 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 7.-Awns of Oryzasativa (a,b, cv. Blackhull Red; c,d, cv. Strawhull Red): a, palea apex (left) and lemma 

(right) with apicular knob and transition to awn base; b. awn base showing microhairs and prickles; c, median 

part of awn; d, awn tip showing bases of aborted prickles. 
NUMBER 91 23 

FIGURE 8.-Otyzu barthii (u.6, IRRI 100224; c,d, IRRI I001 19): a, lower part of spikelet showing callus at base, 

lateral articulation scar, glumes, globose rachilla, lemma, and palea bases; b, lemma with tubercles; c, palea tip 

(left) and lemma tip (right) with apicular knob and awn base; d, median part of awn showing microhairs and 

prickle. 
24 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 9.-0ryza glaberrima (a, TOG7141; b4, TOG5833): a, lower part of spikelet showing pedicel and 

lobed cupule, glumes (offset), globose rachilla, lemma, and palea bases; b, glume with large papillae; c. lemma 

and palea (left) apices, apicular knob, and base of awn; d, lemma showing tubercles, microhairs in furrows, and 

scattered papillae. 
NUMBER 91 

FIGURE IO.-Otyza longistominufa: a, lower part of spikelet showing callus at base with lateral articulation scar, 

globose rachilla, one glume broken off, lemma, and palea bases; 6, glume with two prickles; c,d, lemma with 

tubercles, microhairs in furrows. 

25 
26 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 1 I .--Oryza rufipogont a, lower part of spikelet showing callus with lateral articulation scar, glumes (offset), globose rachilla, lemma, and palea bases; 6, giume with silica bodies; c, lemma and palea with exserted stigmas; d. lemma with tubercles, microhairs, and prickles. 
NUMBER 91 27 

FIGURE12.--Oryza grandiglumis: a. lower part of spikelet showing small callus at base, glumes absent, extra 

pair of lemmas(outer), small rachilla, inner lemma, and palea; b, pedicel with cupule surroundingvascular cylinder but free distally from it; c, lemma showing tubercles and microhairs; d, pedicel showing microhairs, stomata, 

and prickle. 
28 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 13.--Oryza aha (a,b), Oryza Ialifoliu (c): a. spikelet showing small callus at base, glumes, very small 

rachilla, lemma, palea, marginal prickles, and base of awns; b. lemma showing tubercles and microhairs, c, small 

muricate rachilla. 
NUMBER 91 

FIGURE I.l.-Oryzu aus/ra/ic.nsis (a.c), Oryzapuncra/a (b.4: a,h, lower parts of spikelets showing callus at base 

with oblique articulation scar, glumes, small muricate rachilla, lemma, and palea; c.d. lemmas with tubercles, 

microhairs in furrows, and scattered papillae. 

29 
30 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 15.-Oryza minufa (a,c), Oryza oflcinalis (b,d): a, lower part of spikelet showing callus at base with 

basal articulation scar, glumes, very small rachilla, lemma, and palea; 6, palea (left), lemma apex, and awn base; 

c. lemma with tubercles, microhairs, and prickle; d, lower part ofspikelet, parts as in (a). 
NUMBER 91 

FIGURE 16.--Oryza meyerianu var. meyerianu (Sfrain W1353): a, lower part of spikelet showing callus at base 

with oblique articulation scar, offset glumes, broad indurate rachilla, bases of lemma, and palea; M, lemmas 

showing complex tubercles over furrows and very small microhairs in furrows. 

31 
32 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 17.-Oryzu meyerianu var. grunulutu (u, Kostermans 1200; b,c, IRRl 100162): a, spikelet showing callus, small glumes, wrinkled cylindrical rachilla, lemma, and palea, awn lacking; b, pedicel with microhairs, silica 

bodies, and stomata; c, cupule with prominent silica bodies. 
NUMBER 91 

FIGURE 18.--Oryzu meyerianu var. grunulutu (u,c, Kostermuns 1200; b,d. IRRI 100162): a. callus surface with 

silica bodies and stomata; b, glume lacking apparent epidermal features; c,d. lemmas with complex tubercles 

over furrows, numerous free and fused papillae. 

33 
34 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE I9.--Oryzu ridleyi (a, Buwuldu 6339; M, IRRI 100820): a, apices of palea and lemma, lower part of 

awn; b. callus with silica bodies; c, spikelet with callus at base, offset glumes, cylindrical rachilla, lemma, and 

palea; d, glum with microhairs and prickles. 
NUMBER 91 

FIGURE 2O.-Oryza ridkyi (a,b.d, IRRI 100820; c. Buwulda 6339): a-c, lemma with tubercles, microhairs, and 

prickles; d. awn tip. 

35 
36 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 21.-Otyza brachyantha (ad lRR1 101236; b,c, Richard7 9/7/): a, lower part of spikelet showing large 

stipitate callus extending to lemma base, strongly offset glumes, upper glume located just above lateral articulation scar, palea (narrow) to right, rachilla lacking; b, glume base (right), callus (left) with silica bodies; c, lemma 

with prickles, glume tip, and papillae; d, lemma, enlarged, lacking tubercles. 
NUMBER 91 

FIGURE 22.--Oryza brachyantha (ax, IRRI 101236; d, Richards 9171): a, palea tip (right) and lemma with apicular knob and transition to awn; 6, lemma apex showing coalesced papillae and microhairs; c, transition 

between lemma and awn; d, awn with microhairs and prickles. 

37 
38 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 23.-Oryza schlechferi: a, spikelet showing very small callus, small glumes, lemma and palea smooth 

toward their bases; b, glume with silica body; c, lower smooth part of lemma with silica bodies; d, upper furrowed part of lemma with microhairs in furrows, lacking tubercles. 
NUMBER 9 I 39 

FIGURE 24.-Porteresiu courctutu: a, lower part of spikelet showing callus expanded and disk-like, rachilla lacking, with glumes, lemma, and palea; b, callus below, apparently lacking features; c, left side of lemma; d, lemma, 

near its apex. 
40 SMlTHSONlAN CONTRIBUTIONS TO BOTANY 

FIGURE 25.-Portrresia coarctata: o,h, lemma with stomata, tubercles lacking; c, awn base with stomata; d, awn 

tip. 
NUMBER 91 

FIGURE 26.-Rh,vnchotyzu suhuluru: a, lower part of spikelet showing rounded callus, ovate glumes with prickles on margin, lemma, and palea, rachilla lacking; h, callus with silica bodies; c, lemma with mammiform tubercles and prickles; d, marnmifonn tubercles enlarged. 

41 
42 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 27.-Rhynchoryza suhulufu: a. upper (distal) part of lemma showing microhairs, prickles, and silica 

bodies; h,c, lemma showing stomata, each with four bordering papillae; d, awn with microhairs and prickles. 
NUMBER 91 

FIGURE 2R.-Leersiu nematostachya: a, lower part of spikelet showing stipitate callus with lateral articulation 

scar (right), lemma, and palea, rachilla lacking; b, upper part of callus with silica bodies; c. lemma showing silica 

bodies, microhairs, and prickles, tubercles lacking; d, palea, same as preceding. 

43 
44 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 29.-Leersia nemotostacbya: a, h, transition, lemma apex, and awn base showing coalesced papillae, 

microhairs, and prickles; c,d, awns showing microhairs, stomata, and prickles. 
- Oryza sativa 

-0ryza barfhii 

Oryza glaberrima 

- Oryza longistami

-0ryza alta 

- Oryza australiens

- Oryza grandiglum

Oryza latifolia 

-0ryza rninuta 

- Oryza officinalis 

- Oryza punctata 

Oryza schlechfer

FIGURE 30.-UPGMA cluster phenogram of 16 species of Oryza. (Refer to Table 2 for data set and text for 

description of characters. Groups A, B, C, D, E, and F discussed in text.) 
46 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

Oryza ridle yi 

Oryza schlechteri 

Oryza sativa 

Oryza barthii 

P-+ Oryza glaberrima 

Or yza longistaminata 

Oryza rufipogon 

A 

..I 

Oryza me yeriana var me yeriana 

Oryza meyeriana var granulata 

69 YLeersia nematostach ya 

%Or yza brach yantha 

Oryza alta 

Oryza australiensis 

Oryza grandiglumis 

Oryza latifolia 

Oryza minuta 

Or yza officinalis 

Oryza punctata 

54 

I’ 

B 

FIGURE 3 1 .-Strict consensus tree based on parsimony analysis of 16 species of Oryzu, using 14 

characters described in text and Table 2 (data set). (Bootstrap values indicated where greater than 

50% majority rule. Groups A, B, C, D, E, and F discussed in text.) 
NUMBER 91 

359 

211 1 

++ 2 

47 

-0ryza sativa 

-0ryza barthii 

-0ryza glaberrima 

-0ryza longis tamina ta 

-0ryza rufpogon 

2111 

36 

++ 12 

FIGURE 32.4ne of 15 equally parsimonious trees (length=2 1 steps, CI excluding uninformative characters = 

0.75; R1=0.86) analyzing 16 species of Ova with Leersiu as an outgroup. (Solid bars=unique origin of states 

(synapornorphies) and hollow bars=reversals or parallel states.) 

-0ryza aka 

-0ryza aus traliensis 

-0ryza grandiglumis 

-0ryza la tifoia 

-0ryza minuta 

-0ryza officinalis 

-0ryza punctata 
48 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

2. 14 

+Porteresia coarctata 

33 

3 4 8 11 13 

-0ryza schlechteri 

-MI)-cOryza brach yantha 

12311 

123 

223 

Oryza ridle yi 

Or yza me yeriana var me yeriana 

Oryza me yeriana var granulata 

12 

2 

L, 11 

Oryza sativa 

Oryza barthii 

Oryza glaberrima 

Oryza longistaminata 

Oryza rufipogon 

""I Oryza alta 

Oryza aus traliensis F 

Oryza grandiglumis 

Oryza latifolia 

Oryza minuta 

Oryza officinalis 

Oryza punctata 

FIGURE 33.4ne of 16 equally parsimonious trees (length=23 steps, CI excluding uninformative 

characten=0.78; RI=0.88) analyzing 16 species of Otyzo with Porteresia as an outgroup. (Solid 

bars=unique origin of states (synapomorphies) and hollow bars=reversals or parallel states.) 
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