SMITHSONIAN CONTRIBUTIONS TO BOTANY 0 NUMBER 83 

Caryopsis Morphology and 

Classification in the 

Triticeae (Pooideae: Poaceae) 

Edward E. Terrell and Paul M. Peterson 

SMITHSONIAN INSTITUTION PRESS 

Washington, D.C. 

1993 
ABSTRACT 

Terrell, Edward E., and Paul M. Peterson. Caryopsis Morphology and Classification in the 

Triticeae (Pooideae: Poaceae). Smithsonian Contributions to Botany, number 83, 25 pages, 12 

figures, 3 tables, 1993. Detailed descriptions and drawings of caryopses are presented for 35 

species representing 18 genera in the Triticeae. We studied the morphological variation in 

non-embryo characters involving the length, shape, compression, lateral ridges, sulcus 

development, coronas, and apical hairs of the caryopsis. Based on shared characters of the 

caryopses, we recognize three groups of genera as two major subtribes and one monogeneric 

subtribe. The Hordeinae includes Agropyron, Crithopsis, Elymus, Elytrigia, Eremopyrum, 

Hordelymus, Hordeum, Leymus, Psathyrostachys, and Taeniatherum; Triticinae includes 

Aegilops, Amblyopyrum, Dasypyrum, Heteranthelium, Secale, and Triticum; and Henrardiinae 

includes Henrardia. Similarities among the caryopses of 14 species of Elymus, Elytrigia, 

kymus, and Psathyrostachys support a broad interpretation of Elymus. The caryopses of 

Brachypodium resemble those of the genera in the Hordeinae and to some extent Bromus. 

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

recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: Leaf 

clearing from the katsura tree Cercidiphyllum japonicum Siebold and Zuccarini. 

Library of Congress Cataloging-in-Publication Data 

Terrell, Edward E. 

Caryopsis morphology and classification in the Triticeae (Pooideae: Poaceae) / Edward E. Terrell and Paul M. 

Peterson. 

p. cm.-(Smithsonian contributions to botany ; no. 83) 

Includes bibliographical references. 

1. Grasses-Classification. 2. Caryopses. I. Peterson, Paul M. 11. Title. 111. Series. 

QK1 .S2747 110.83 [QK495.G74] 58 1 s-dc20 [584'.93] 92-47245 

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

National Standard for Permanence of Paper for Printed Library Materials 239.48-1984. 
Contents 

Page 

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

Materials and Methods ............................... 1 

Acknowledgments .................................. 2 

Results ........................................... 2 

Non-embryo Characters and Their Variation ..................... 2 

Descriptions of Caryopses ............................... 3 

Elymus sibiricus .................................... 3 

Elymusdahuricus .................................... 3 

Elymus caninus ..................................... 3 

Elymus hystrix ..................................... 4 

Elymus elymoides .................................... 6 

Elymus distichus .................................... 6 

Elytrigia repens subsp . repens ............................. 6 

Elytrigia elongata subsp . elongata ........................... 6 

Elytrigia spicata .................................... 6 

Leymus arenarius .................................... 6 

Leymus angustus .................................... 6 

Leymus alaicus subsp . karataviensis .......................... 6 

Psathyrostachys juncea ................................ 9 

Psathyrostachys fragilis ................................ 9 

Hordeum bogdanii ................................... 9 

Hordeum jubatum ................................... 9 

Hordeum spontaneum ................................. 9 

Hordeum distichon ................................... 9 

Hordeum vulgare .................................... 9 

Agropyron cristatum .................................. 9 

Eremopyron triticeum ................................. 9 

Crithopsis delileana .................................. 13 

Hordelymus europaeus ................................ 13 

Taeniatherum caput-medusae ............................. 13 

Aegilops cylindrica .................................. 13 

Aegilops triuncialis .................................. 13 

Amblyopyrum muticum ................................ 13 

Triticum monococcum ................................ 13 

Triticum dicoccon ................................... 13 

Triticum aestivum ................................... 13 

Secale cereale ..................................... 18 

Dasypyrum villosum ................................. 18 

Heteranthelium piliferum ............................... 18 

Henrardia persica ................................... 18 

Brachypodium pinnatum ............................... 18 

Discussion ........................................ 18 

Elymoid Group .................................... 18 

Triticinoid Group ................................... 21 

Henrardioid Group .................................. 22 

Brachypodium Group ................................. 22 
iv SMITHSONIAN CONTRIBUTIONS TO BOTANY 

Caryopses Characteristics of the Triticeae ...................... 22 

Conclusions ....................................... 23 

Literature Cited ..................................... 24 
Caryopsis Morphology and 

Classification in the 

Triticeae (Pooideae: Poaceae) 

Edward E. Terrell 

and Paul M. Peterson 

Introduction 

The Triticeae* is one of the smaller tribes of grasses 

(approximately 330 species), but the most economically 

important, including wheat (Triticum), barley (Hordeum), rye 

(Secale), and some important forage grasses in Elymus and 

Agropyron. This tribe has been subjected to more varied 

classifications than any other tribe of grasses. One extreme 

view, based on successful hybridizations among the genera, 

advocated the recognition of a single genus (Stebbins and 

Walters, 1949). Love (1984) recognized 37 genera by assigning 

generic status to each unique genomic formula. Most of the 

recent reorganizations within the Triticeae have occurred in the 

large genera, Elymus and Agropyron. Agropyron sens. str. now 

includes only the crested wheatgrass complex, centered around 

A. cristatum, and Elymus has been split into several genera 

(Tzvelev, 1976: 147-203, 253-276; Melderis, 1978b, 1980; 

Dewey, 1982, 1983a,b, 1984; Barkworth et al., 1983; Barkworth and Atkins, 1984; Barkworth and Dewey, 1985; Love, 

1982, 1984; Baum 1977; Baum et al., 1991). On the other hand, 

Estes and Tyrl (1982) have argued for a broader circumscription by including many segregate genera within Elymus. More 

recently the genomic and alternative classifications of the 

Triticeae have been addressed by Gupta and Baum (1986), 

Baum et al. (1987), Jauhar and Crane (1989), and Kellogg 

(1989). 

Non-embryo characters of the caryopses have been neglected 

by researchers, yet they can offer important information on 

phylogenetic relationships. At least within some groups, the 

caryopses may be an important part of the grass flower for 

taxonomy. Characteristics of the caryopses other than the 

Edward E. Terrell. Department of Botany, University of Maryland, 

College Park, Maryland 20742. Paul M. Peterson, Department of 

Botany, National Museum of Natural History, Smithsonian Institution, 

Washington, D.C. 20560. 

embryo have been investigated by certain authors, e.g., Martin 

(1946), Yakovlev (1950), Kuwabara (1962), Bogdan (1966), 

Terrell (1 97 I), Rosengurtt et al. (1 97 l), Watson and Clifford 

( 1976), Koch (1 979), and MacFarlane and Watson (1 980, 

1982). Other papers included a survey of non-embryo 

characteristics within a genus or tribe, e.g., Bayles and Clark 

(1954) on Triticum; Colbry (1957) on Sporobolus; Reeder 

(1965) on Orcuttieae; Kowal and Rudnicka-Stemowa (1969) 

on Bromus; and Brandenburg et al. (1991) on Diarrhena. 

The purposes of the present study are to evaluate the 

morphological structure of the caryopses within the Triticeae 

and to determine the importance of non-embryo characters in 

the classification of this tribe. 

belonging to 18 genera of Triticeae were obtained from plants 

grown at the United States Department of Agriculture (USDA) 

facilities or from herbarium specimens at the United States 

National Herbarium (US) or the Royal Botanic Gardens, Kew 

(K). Specimens from the USDA usually have Plant Introduction (PI) numbers or Cereal Investigation (CI) numbers. The CI 

numbers are used for well-known crops and are materials 

derived from cultivated plots at USDA field stations. The 

sources of our material follow each species’ caryopses 

description. Voucher specimens and caryopses are deposited at 

US. We selected genera and species that would provide 

representative samples of the variation present in the Triticeae. 

The type species and other species representing different 

sections of a genus were included when possible. The samples 

were compared with other collections of the same species to 

confirm their identities. We were unable to obtain mature 

caryopses of the recently described genera, Festucopsis (C.E. 

Hubbard) Melderis (Melderis, 1978a), native to Albania and 

Greece, and Kengyilia Yen & Yang (Yen and Yang, 1990), 

*Authors of scientific names are given in text or tables. 

MATERIALS AND METHODS.-caryopses Of 35 Species 

1 
2 

native to China. 

Mature, dry caryopses were examined with a low-power 

stereo microscope and the most important characters were 

described for each species. When available, more than one 

accession was examined to study the variation, and additional 

accessions were drawn for certain species to show the variation. 

Consequently, the description and illustration for each species 

were derived from one to several accessions. The caryopses 

were drawn in four aspects: ventral, lateral, and dorsal views; 

and transverse section. 

Scanning electron microscopy (SEM) was conducted by 

direct mounting of the dry caryopsis on an aluminum stub and 

coating with gold palladium. Samples were then examined 

using SEM and photographed. 

The working classification adopted for the purpose of study 

arranges the genera according to genome (Table 1) starting with 

Elymus and includes the sometimes segregated genera Elytrigia, Leymus, and Psathyrostachys. Elymus is employed in a 

rather restricted sense and Aegilops and Triricum are treated as 

distinct. Sitanion and Hystrix are tentatively included in Elymus 

because they share the same genome (Dewey, 1984:246-250; 

Love, 1982, 1984:447). Henrardia is included in the tribe in 

agreement with Hubbard (1 946) and recent literature. Brachypodium is added to this study because Clayton and Renvoize 

(1986) included the genus in their treatment of the Triticeae and 

Macfarlane and Watson ( 1982) and Kellogg (1989) have 

recognized the genus as a sister group to the tribe. 

ACKNOWLEDGMENTS.-We dedicate this paper to Regina 0. 

Hughes in recognition of her long and distinguished career as a 

botanical artist, as well as for her accurate and artistic drawings 

that are presented here. Financial support during early parts of 

the study was provided by the Agricultural Research Service, 

USDA, Beltsville, Maryland. We would like to thank G.A. 

White, USDA Plant Introduction Office, D.H. Smith, Jr., 

National Small Grain Collection, USDA, and S.A. Renvoize, 

Royal Botanic Gardens, Kew, for providing material for-study. 

A. Tangerini assisted with the illustrations and M.T. Strong 

aided in the preparation of the literature cited. Access to the 

scanning electron microscopy equipment at USDA was 

provided by W.P. Wergin. We also thank J.R. Estes, S. 

Frederiksen, and T.D. Pizzolato for suggesting important 

modifications that significantly improved the manuscript. 

Results 

NON-EMBRYO CHARACTERS AND THEIR VARIATION.-The 

non-embryo morphological characters determined to be the 

most important for revealing relationships among the genera 

are as follows: caryopsis length and shape; type of compression, whether dorsiventral, dorsiventral with compressed 

ventral face only, lateral, or none; extent of compression; 

presence or absence of lateral ridges and the extent of their 

development; sulcus depth and width and their extent; whether 

sulcus is widened distally; corona length and whether vertical 

SMITHSONIAN CONTRIBUTIONS TO BOTANY 

TABLE 1 .--Genera and species examined, genome, and figure number. 

Taxon 

~~ ~~ 

ELYMOID GROUP 

Elymus sihiricrts 

E. dahuricus 

E. caninus 

E. hysirix 

E. elymoides 

E. distichus 

Elytrigia repens 

E. elongaru 

E. spicata 

Leymrts arenarius 

L. angusius 

L. alaicus subsp. karaiaviensis 

Psaihyrosrachys juncea 

P. fragilis 

Hordeum hogdanii 

H. juharum 

H. prtsillum 

H. sponianeum 

H. disiichon 

H. vrtlgare 

Agropyron crisiairtm 

Eremopyrum iriticrum 

Criihopsis delileana 

Hordelymus errropaeus 

Tueniaiherum cupui-medusae 

Aegilops cylindrica 

A. trirtncialis 

Amblyopyrum muiicum 

Triiicum monococcum 

I: dicoccon 

I: aesiivum 

Secale cereale 

Dusypyrum villosum 

Heieranthelium piliferum 

HENRARDIOID GROUP 

Henrardia persica 

BRACHYPODIUM GROUP 

Brachypodium pinnatum 

TRITICINOID GROUP 

Genome Figure 

SH 

SH 

SH 

SH 

SH 

J, JE 

SX, S, E, J 

E 

S 

JN 

JN 

JN 

N 

N 

H 

H 

H 

I 

I 

I 

P 

F 

K 

HT 

T 

CD 

cu 

Z 

A 

AB 

ABD 

R 

V 

Q 

0 

- 

2 

2 

2 

2 

3 

3 

3 

3 

4 

4 

4 

4 

5 

5 

5 

5 

1 

6 

6 

6 

7 

7 

8 

8 

8 

9 

10 

10 

11 

11 

11 

11 

12 

12 

12 

12 

or cap-like; density and length of apical hairs; and embryo 

length relative to caryopsis length. 

The Triticeae have relatively large caryopses ranging from 

(2.5-) 3.5-1 1 mm long in the species studied. Shapes of these 

in outline varied from oblanceolate or oblong to lanceolate, 

elliptic, or ovate. The most common compression is moderately 

to strongly dorsiventral, but compression varies to none or to 

slightly or strongly laterally compressed. Compression is 

differential in Aegilops cylindrica and A. triuncialis (Figures 9, 

lo), in which the caryopses are flattened on the ventral face and 

rounded on the dorsal face. An additional character is the 

presence of low lateral ridges extending longitudinally that are 

visible in transverse sections. These occur in Crithopsis, 

Hordelymus, and Taeniatherum (Figure 8) and are very small 
NUMBER 83 3 

or obscure in certain species of Elymus (Figure 3d). Another 

important character is the presence or absence of a sulcus 

(Bayles and Clark, 1954; Steam, 1973), also called the furrow 

or groove. Depth of the sulcus varies from shallow to deep. Its 

margins may be flattened or more often form a rim, as in 

Elymus (Figures 2e-m, 3a-d). The width of the sulcus varies 

from wide and broadly U-shape to narrow or entirely closed by 

the fusion of the margins. The sulcus may be wider toward the 

apex of the caryopsis, particularly in Elymus (Figure 2e-m). 

Both faces of the caryopsis may be strongly compressed and 

the sulcus very shallow (e.g., Henrardia, Figure 12j-m). 

The small membranous corona is attached to the apex of the 

caryopsis and varies from whitish to yellowish. The corona 

may be partly concealed by the apical hairs. In Triticum 

relatives, especially Dasypyrum (formerly Haynaldia) and 

Heteranthelium, the corona is a smooth or angulate cap (Figure 

12a-d). Apical hairs range from long to short and may densely 

or sparsely cover the surface. The apex may be glabrous or 

glabrate in some individuals of Dasypyrum, Heteranthelium, 

Hordeum distichon, H. vulgare, and Secale cereale. 

Embryo lengths in species studied varied from (*/5-) I/3- 

'/5 (-l/6) as long as the caryopsis (all measurements include the 

apical hairs). When viewed under low power the embryo and 

adjacent areas seem to show some variation among the taxa, but 

further examination would require special methods that were 

not included in this study. 

Scanning electron microscopy of the caryopsis of Hordeum 

pusillum shows the shape, relative size of the embryo, and 

details of the unicellular tapering apical cells (Figure la-c). 

Also shown is the spermoderm or outer coat (Figure 1 a), which 

some authors have utilized for distinguishing genera or species 

(e.g., Korber-Grohne, 1981; Buth, 1982; Jordan et al., 1983). 

Under low magnification we did not see any conspicuous 

differences in the spermoderms of the Triticeae reviewed for 

this study. 

DESCRIPTIONS OF CARY0PsEs.-Morphological descriptions of the caryopsis and background data are given starting 

with Elymus (Table 1). Each description is accompanied by the 

accepted name, synonyms, genome, chromosome number, and 

geographical distribution; sometimes recent classifications and 

comments are added. It should be especially noted that each 

description may be based on accessions additional to the one 

illustrated. Genomes and chromosome numbers are in brackets. 

Main sources for the data on genomes were taken from Dewey 

(1984) and Love (1984); for chromosome numbers 'Tzvelev 

(1976), Melderis (1978b, 1980), Dewey (1982), and Love 

(1984); for geographic distribution Hitchcock (1951) and 

Tzvelev (1976). The source for each collection is given and the 

illustrated collection(s) is marked with an asterisk if more than 

one accession is listed. More detailed collection data can be 

provided on request. 

For some characters subjective terms such as dense or sparse 

are employed. In order to provide a reference point, the 

following terms are exemplified by citing a particular species 

along with a specific figure in the illustrations. The extent of 

compression of the caryopses is given as slight (Eremopyrum 

triticeum, Figure 71,p), moderate (Elymus sibiricus, Figure 2d), 

or strong (Crithopsis delileana, Figure 8d). Sulcus depth is 

recorded as shallow (Elymus sibiricus, E. dahuricus, E. 

caninus, and E. hystrix, Figure 2), medium (Eremopyrum 

triticeum, Figure 71,q), or deep (Triticum dicoccon, Figure 

I 1 h). Sulcus widths are recorded as wide (Elytrigia spicatu, 

Leymus arenarius, and L. alaicus, Figure 4d,h,p), medium 

(Eremopyrum triticeum, Figure 7p,q), narrow (Hordeum 

distichon, Figure 6h), or very narrow or closed (Aegilops 

cylindrica, Triticum monococcum, I: dicoccon, and I: aestivum, Figures 9d,e,o, 1 ld,h,l). The sulcus is sometimes wider 

distally, i.e., toward the apex in Elymus dahuricus and E. 

caninus (Figure 2e,i). The density of apical hairs on the corona 

is categorically determined to be either dense (Elymus 

sibiricus, E. dahuricus, E. caninus, E. hystrix, and E. 

elymoides, Figure 2c,g,k,p) or sparse (Eremopyrum triticeum, 

Figure 7k,o). Length of apical hairs is considered short 

(Brachypodium pinnatum, Figure 12n), medium (Hordeum 

juhatum, Figure 5m,n,o), or long (Elymus hystrix, Figure 

2n,o,p). 

Elymus sibiricus Linnaeus [Clinelymus sibiricus (Linnaeus) 

Nevski] [SH; 2n = 281. The type species of Elymus, occurs 

from Ural region and Baltic region to eastern Asia and 

northwest North America. 

Caryopses: 5-5.5 mm long; oblanceolate or oblong; compression dorsiventral, moderate, dorsal face rounded; 

lateral ridges none; sulcus shallow, medium, or 'wide; 

corona -0.5 mm long; apical hairs dense, length medium; 

embryo I/5-I/6 as long as caryopsis (Figure 2a-d). (*PI 

362191, Mongolia; K.M. Liou L428, China (US); PI 

326267 and PI 370673, cultivated at Vavilov Institute, St. 

Petersburg, Russian Federation.) 

Elymus dahuricus Turczaninow ex Grisebach [Clinelymus 

dahuricus (Turczaninow ex Grisebach) Nevski] [SH; 

2n = 28, 421. Placed in Elymus sect. Turczaninovia 

(Nevski) Tzvelev by Tzvelev (1976:157). It occurs from 

Iran to eastern Asia. 

Caryopses: 4.5-5.5 mm long; oblanceolate or oblong; 

compression dorsiventral, moderate, dorsal face rounded; 

lateral ridges none; sulcus shallow, wide throughout or 

medium at base and widened distally; corona 0.5-1 mm 

long; apical hairs dense, length medium; embryo '/5 as 

long as caryopsis (Figure 2e-h). (PI 314680, Uzbekistan.) 

Elymus caninus (Linnaeus) Linnaeus [Agropyron caninum 

(Linnaeus) P. Beauvois; Roegneria canina (Linnaeus) 

Nevski] [SH; 2n = 281. Native to Europe and temperate 

Asia, traditionally it has been in Agropyron but was placed 

in Elymus sect. Goulardia (Husnot) Tzvelev by Tzvelev 

(1 976: 158) and Melderis ( 1978b, 1980). 
4 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURE 1 .-Scanning electron micrographs of the caryopsis of Horderrm pusillurn. (Scale bars: a = 500pm; 

b,c = 50pm.) 

Caryopses: 5-6 mm long; oblanceolate or oblong; compres- Elymus hystrix Linnaeus [Hysrrix patula Moench] [SH, 

2n=28]. It occurs in eastern Canada and eastern and 

central United States. 

Caryopses: 5.5-6 mm long; oblanceolate or oblong; compression dorsiventral, moderate, dorsal face rounded, 

lateral ridges none; sulcus shallow, wide throughout or 

sion dorsiventral, moderate, dorsal face rounded; lateral 

ridges none; sulcus shallow, wide throughout or medium at 

base and widened distally; corona 0.5-1 mm long; apical 

hairs dense, length medium; embryo l/5 as long as 

caryopsis (Figure 2i-m). (PI 314616, Uzbekistan.) 
NUMBER 83 5 

a 

i 

b 

i 

1 

I' 

1 

k 

m 

e 

n 

f 

I 

0 

1 

I' 

FIGURE 2.4aryopsis of Elymus sibiricus (a-d); Elymus dahuricus (e-h); Elymus caninus (i-m): and Elymus 

hystrix (n-q). Ventral views (u,e,i,n): lateral views (b,f,j,o); dorsal views (c,g,kp); transverse sections (d,h,l,m,q). 

(All scale bars = 1 mm.) 
6 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

medium at base and widened distally; corona 0.8- 1.2 mm 

long; apical hairs dense, long; embryo l/4 as long as 

caryopsis (Figure 2n-q). (Terrell & Meyer 4318, Peny 

Co., Indiana.) 

Elymus elymoides (Rafinesque) Swezey [Sitanion hystrix 

(Nuttall) J.G. Smith] [SH; 2n = 281. Native in central and 

western United States and western Canada. 

Caryopses: 5-6 mm long; oblanceolate or oblong; compression dorsiventral, moderate, dorsal face rounded; lateral 

ridges rudimentary; sulcus shallow to medium, wide 

throughout or medium at base and widened distally; 

corona 0.5-1 mm long; apical hairs dense, length short to 

medium; embryo l/5 as long as caryopsis (Figure 3a-d). 

(Terrell & Wheeler s.n., 6 Jul 1978, Rosebud Co., 

Montana.) 

Elymus distichus (Thunberg) Melderis [Agropyron distichum 

(Thunberg) P. Beauvois; Thinopyrum distichum (Thunberg) A. Love] [J fide Love, 1984:476, JE fide Dewey, 

1984:274; 2n = 281. Native to South Africa. 

Caryopses: 9-10.5 mm long; lanceolate, narrowly elliptic; 

compression dorsiventral, moderate to strong, dorsal face 

rounded, lateral faces narrow; lateral ridges none; sulcus 

medium to deep, wide throughout; corona 1-2 mm long, 

conspicuous, wider than apex of caryopsis (drawing shows 

fragile styles); apical hairs sparse to dense, short; embryo 

l/4-]/5 as long as caryopsis (Figure 3e-h). (K.C. Johnson 

s.n., Feb 1977, coast of Western Cape, Republic of South 

Africa, via USDA.) 

Elytrigia repens (Linnaeus) Nevski subsp. repens [Agropyron 

repens (Linnaeus) P. Beauvois; Elymus repens (Linnaeus) 

Gould] [SX fide Dewey, 1984:276; E, J, and S fide Love, 

1984:484; 2n = 42, also 28, 561. This species, the type of 

Elytrigia, traditionally was placed in Agropyron. It was 

assigned to Elymus sect. Elytrigia (Desvaux) Melderis by 

Melderis (1978b). It occurs in Europe, Asia, North Africa, 

and as a weed in North America, South America, and 

Australia (Bor, 1968:220, 221; Tzvelev, 1976: 196). 

Caryopses: 4.5-5.5 mm long; oblong; compression dorsiventral, slight, dorsal face rounded; lateral ridges none; 

sulcus depth shallow to medium, width medium at base 

and slightly widened distally; corona 0.5-1 mm long; 

apical hairs dense, short; embryo '/4-]/5 as long as 

caryopsis (Figure 3i-1). (Dewey s.n., Apr 1972, Utah, via 

USDA.) 

Elytrigia elongata (Host) Nevski subsp. elongata [Agropyron 

elongatum (Host) P. Beauvois; Lophopyrum elongatum 

(Host) A. Love; Thinopyrum elongatum (Host) D.R. 

Dewey; Elymus elongatus (Host) Runemark] [E 2n = 141. 

Occurs in Mediterranean region to southwest and probably 

central Asia. It was traditionally in Agropyron but was 

placed in Elytrigia sect. Caespitosae (Rouy) Tzvelev 

(Tzvelev, 1976: 194, 195) and in Elymus sect. Caespitosae 

(Rouy) Melderis (Melderis, 1978b). 

Caryopses: 5-6.5 mm long; oblong; compression dorsiventral, moderate, dorsal face rounded; lateral ridges 

none; sulcus shallow, wide throughout or medium at base 

and widened distally; corona 0.5-1 mm long; apical hairs 

dense, short; embryo I/? as long as caryopsis (Figure 

3m-p). (PI 264770, Germany.) 

Elytrigia spicata (Pursh) D.R. Dewey [Agropyron spicatum 

(Pursh) Scribner & Smith; Pseudoroegneria spicata 

(Pursh) A. Love; Elymus spicatus (Pursh) Gould] [S; 

2n = 14, 281. Ranges from central and western North 

America to Alaska. Traditionally in Agropyron, it has been 

placed in Elymus sect. Caespitosae (Rouy) Melderis 

(Melderis, 1978b) or Elytrigia sect. Caespitosae (Rouy) 

Tzvelev (Tzvelev, 1976) or in Pseudoroegneria (Nevski) 

Love. 

Caryopses: 4-5.5 mm long; oblong or narrowly elliptic; 

compression dorsiventral, strong to moderate, dorsal face 

slightly rounded; lateral ridges none; sulcus deep, wide 

throughout; corona 0.5-1 mm long; apical hairs dense, 

length medium; embryo l/4-]/5 as long as caryopsis 

(Figure 4a-d). (*Terrell 4783, Davis Co., Utah; Terrell 

s.n., 26 Jul 1977, Bingham Co., Idaho; Terrell & Wheeler 

s.n., 7 Jul 1978, Rosebud Co., Montana.) 

Leymus arenarius (Linnaeus) Hochstetter [Elymus arenarius 

Linnaeus] [JN; 2n =56]. This type species occurs in 

Europe and eastern Europe. 

Caryopses: 7-8.5 mm long; oblanceolate or oblong; compression dorsiventral, moderate to strong, dorsal face 

flattened to somewhat rounded, lateral faces sometimes 

flattened; lateral ridges none; sulcus depth medium, wide; 

corona 1-2 mm long; apical hairs dense, long; embryo l/4 

as long as caryopsis (Figure 4e-h). (*PI 316233, cultivated in Russian Federation; PI 345979, Norway.) 

Leymus angustus (Trinius) Pilger [Elymus angustus Trinius] 

[JN; 2n =28, 42, 56, 841. Occurs in central Asia and 

Siberia. It was classified in Leymus sect. Aphanoneuron 

(Nevski) Tzvelev by Tzvelev (1976:263,264). 

Caryopses: 7.5-8.5 mm long; oblong or lanceolate; compression dorsiventral, moderate, dorsal face rounded; 

lateral ridges none or inconspicuous; sulcus depth medium, width medium to wide; corona 1-2 mm long; apical 

hairs dense, long; embryo ]/s as long as caryopsis (embryo 

area bearing short, sparse hairs) (Figure 4i-I). (PI 271893, 

USSR, via Canada.) 

Leymus alaicus subsp. karataviensis (Roshevits) Tzvelev 

[Elymus karataviensis Roshevits; Elymus alaicus Korsh, 

sens. lat.; Aneurolepidium karataviense (Roshevits) 

Nevski] [JN; 2n = 281. Native to central Asia. Nevski 

( 1934:704) placed it in Aneurolepidium and Tzvelev 
NUMBER 83 7 

a 

i lk 

e 

1 

1 

l4 

m n 0 

1 

1 

FIGURE 3.-Caryopsis of Elymus elymoides (a-d); Elymus distichus (e-h); Elyrrigia repens (i-1); and Elytrigiu 

elongaru (m-p). Ventral views (a,e,i,m); lateral views (h.f,j,n); dorsal views (c,g,k,o); transverse sections (d,h,l,p). 

(Allscales = 1 mm.) 
8 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

a 

i 

1 

k a1 

e 

m 

I 

f 

1 

0 n 1 

FIGURE 4.-Ca~yopsis of Elytrigia spicata (a-d); Leymus urenarius (e-h); Leymus angustus (i-I); and Leymus 

alaicus subsp. kuraruviensis (m-p). Ventral views (a,e,i,m); lateral views (h,f,j,n); dorsal views (c,g,k,o); 

transverse sections (d.h,l,p). (All scales = 1 mm.) 
NUMBER 83 9 

(1976:263, 264) put it in LRymus sect. Aphanoneuron 

(Nevski) Tzvelev. 

Caryopses: 5-6 mm long; oblong; compression dorsiventral, 

moderate, dorsal face rounded; lateral ridges very small: 

sulcus depth shallow to medium, width medium to wide, 

widened distally; corona 0.5-1 mm long; apical hairs 

dense, length medium to long; embryo I/4-l/5 as long as 

caryopsis (Figure 4m-p). (PI 314671, USSR.) 

Psathyrostachys juncea (Fischer) Nevski [Elymus junceus 

Fischer] [N; 2n = 141. Ranges from eastern Europe to 

central Asia, Tibet, and Mongolia. 

Caryopses: 4-5 mm long; oblanceolate or oblong; compression dorsiventral, moderate, dorsal face rounded; lateral 

ridges none or small; sulcus depth medium, width medium 

to wide; corona 0.5-1 mm long; apical hairs dense, length 

medium; embryo I/4-'/5 as long as caryopsis (Figure 

5a-d). (*PI 314082, Stavopol Botanical Garden, 

Russian Federation; PI 370672, Uzbekistan; PI 314668, 

Uzbekistan.) 

Psathyrostachys fragilis (Boissier) Nevski [Elymus fragilis 

(Boissier) Grisebach; Hordeum fragile Boissier] [N; 

2n = 141. Native to Asia Minor and southwest Asia. 

Caryopses: 6.5-7.5 mm long; oblong; compression dorsiventral, moderate, dorsal face rounded; lateral ridges 

very small; sulcus depth medium, width medium to wide; 

corona 0.5-1 mm long; apical hairs dense, length medium 

to short; embryo l/5 as long as caryopsis (Figure 5e-h). 

(Dewey 11 86, CL 33- 17, Iran, via USDA.) 

Hordeum bogdanii Wilensky [Critesion bogdanii (Wilensky) 

A. Love] [H; 2n = 141. Native in Transvolga, lower Don, 

and lower Volga regions to Tibet and Mongolia. Placed in 

Hordeum subg. Hordeastrum (Doell) Rouy by Tzvelev 

Caryopses: 4.5-5.0 mm long; oblong or lanceolate; compression dorsiventral, moderate to strong, dorsal face 

somewhat rounded; lateral ridges none; sulcus shallow to 

medium, width medium; corona -0.5 mm long; apical 

hairs dense, width medium; embryo I/4-l/5 as long as 

caryopsis (Figure 5-1). (PI 269406, Afghanistan.) 

Hordeum jubatum Linnaeus [Critesion jubatum (Linnaeus) 

Nevski] [H; 2n = 14, 28, 421. Occurs from upper Volga 

region to eastem Asia, introduced in North America. 

Traditionally placed in Hordeum, but moved to Critesion 

by Nevski (1934:721, 722), and treated in Hordeum subg. 

Hordeastrum (Doell) Rouy by Tzvelev (1 976:28 1-284). 

Caryopses: 3.5-4 mm long; oblanceolate or elliptic; compression dorsiventral, moderate to strong, dorsal face 

somewhat rounded; lateral ridges none; sulcus shallow, 

wide, slightly widened distally; corona -0.5 mm long; 

apical hairs sparse to dense, length short to medium; 

embryo '/4 as long as caryopsis (Figure 5m-p). (Terrell 

s.n., 6 Jul 1977, Cache Co., Utah.) 

(1976:28 1-283). 

Hordeum spontaneum K. Koch [H. ithahurense Boissier; H. 

vulgare subsp. sponraneum (K. Koch) Ascherson & 

Graebner] [I; 2n = 141. Distributed from the Mediterranean 

region to central Asia. Placed in Hordeum subg. Hordeum 

by Tzvelev (1 976:287). 

Caryopses: 9- 10 mm long; narrowly elliptic; compression 

dorsiventral, moderate, dorsal face flat or rounded; lateral 

ridges very small; sulcus shallow, narrow at base, widened 

to medium distally; corona 1-1.5 mm long, somewhat 

bilobed: apical hairs sparse, short; embryo I/4 as long as 

caryopsis (Figure 6a-d). (*P1466124, Syria; PI 466221, 

Syria; PI 466228, Syria.) 

Hordeum distichon Linnaeus [Hordeum vulgare subsp. distichon (Linnaeus) Koemicke] [I; 2n = 141. Sometimes 

cultivated. 

Caryopses: 8-8.5 mm long; elliptic; compression dorsiventral, slight, dorsal face rounded; lateral ridges none; 

sulcus shallow, narrow, widened distally to medium; 

corona 0.5-1 mm long; apical hairs sparse and short or 

lacking; embryo l/3 as long as caryopsis (Figure 6e-h). 

Hordeum vulgare Linnaeus [I; 2n = 141. The type species is 

cultivated worldwide. 

Caryopses: 7-10.5 mm long; elliptic or ovate; compression 

dorsiventral, slight or none (caryopsis round in transverse 

section); lateral ridges none; sulcus shallow, narrow, 

widened to medium at distal end; corona 0.5- 1.5 mm long, 

conspicuous; apical hairs sparse and short, or lacking; 

embryo '/4 as long as caryopsis (Figure 6i-n). (*CI 

10640-cv. Bonneville 70; *PI 328933, cult. in Israel; *PI 

356732, cult. in Wales; CI 14003.) 

(*CI 14311; CI 14310.) 

Agropyron cristatum (Linnaeus) Gaertner sens. lat. [P; 2n = 14, 

28, 421. The type species is native in Europe and Asia, 

introduced in North America. 

Caryopses: 3.5-4.5 mm long; oblong or lanceolate: compression dorsiventral, slight, dorsal face rounded; lateral 

ridges none; sulcus depth shallow to medium, width 

medium to narrow, slightly to somewhat widened distally; 

corona 0.5-1 mm long: apical hairs dense to sparse, short; 

embryo l/4-]/5 as long as caryopsis (Figure 7a-h). (*PI 

297869 (Figure 7e-h), Turkey; *PI 314596 (Figure 

7a-d), Uzbekistan; PI 330686, Iran.) 

Eremopyrum triticeum (Gaertner) Nevski (Agropyron triticeum 

Gaertner) [F; 2n = 141. Native in southeast Europe and 

Asia Minor to central Asia, adventive in North America. 

Caryopses: 2.5-4 mm long; lanceolate or ovate; compression dorsiventral, slight; dorsal face rounded; lateral 

ridges none; sulcus depth medium, narrow at base, 

widened to medium or wide distally; corona -0.2-0.5 mm 

long, bilobed; apical hairs sparse, short; embryo l/4 as long 

as caryopsis (Figure 7i-q). (Terrell 4935, Crook Co., 

Wyoming.) 
10 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

a b 

1 

i 

lC 1 

i 

I 

1 

e 

m 

1 

n 

1 

0 1 1 

FIGURE 5.--Caryopsis of Psathyrostachys juncea (a-d); Psathyrostachys fragilis (e-f ); Hordeurn bogdanii 

(i-4; and Hordeum jubatum (rn-p). Ventral views (a,e,i,rn); lateral views (b,f, j,n); dorsal views (c,g,k,o); 

transverse sections (d,h,lp). (All scales = 1 mm.) 
NUMBER 83 11 

a C b 

1 

e 

1 

i i k 

f 

1 

1 

1 

FIGURE 6.4aryopsis of Hordeum spontuneum (u-d); Hordeum distichon (e-h); and Hordeum vulgare (i-n). 

Ventral views (u,e,i); lateral views (b,f,j); dorsal views (c,g,k); transverse sections (d,h.l.m,n). (All scales = 1 

mm.) 
12 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

a 

i 

b 

1 

J 

1 

C 

1 

I* 

e 

m 

f 

n 

1 

Ig 

1 

0 

FIGURE 'I.--Caryopsis of Agropyron urisfafum (a-h) and Eremopyrum rrificeum (i-q). Ventral views (a,e,i,m); 

lateral views (h,f.j,n); dorsal views (c,g,k,o); transverse sections (d,h,l,p,q). (All scales = 1 mm.) 
NUMBER 83 13 

Crithopsis delileana (Schultes) Roshevits [Elymus delileanus 

Schultes] [K; 2n = 141. Ranges from the Mediterranean 

region to Iran (Bor, 1970:219; Melderis, 1980). 

Caryopses: 4.5-5.5 mm long; lanceolate or narrowly 

elliptic; compression dorsiventral, strong, dorsal and 

ventral faces flattened; lateral ridges conspicuous; sulcus 

deep, width medium; corona 0.5-1 mm long; apical hairs 

sparse to dense, short; embryo l/4 as long as caryopsis 

(Figure 8a-d). (*Bornmiller s.n., Nov. 1895, Palestine 

(US); Barkley & Brahim M. 1337, Iraq (US).) 

Hordelymus europaeus (Linnaeus) C. Harz [Elymus europaeus 

Linnaeus; Hordeum europaeum (Linnaeus) Allioni; Cuviera europaea (Linnaeus) Koeler] [HT; 2n = 281. Ranges 

from Europe to southwest Asia. 

Caryopses: 7-7.5 mm long; narrowly lanceolate; compression dorsiventral, strong, dorsal face somewhat 

rounded; lateral ridges conspicuous; sulcus depth medium 

to deep, width medium; corona 0.5-1 mm long; apical 

hairs sparse to dense, length short to medium; embryo 

l/5-I/6 as long as caryopsis (Figure 8e-h). (E. Nelmes 151, 

England (US).) 

Taeniatherum caput-medusae (Linnaeus) Nevski, sens. lat. 

[Elymus caput-medusae Linnaeus; including i7 asperum 

(Simonkai) Nevski and i? crinitum (Schreber) Nevski] [T; 

2n = 141. Occurs in Europe and North Africa and ranges to 

central Asia and the Himalayas. 

Caryopses: 5.5-9 mm long; narrowly lanceolate; compression dorsiventral, strong, dorsal face rounded; lateral 

ridges conspicuous; sulcus medium to deep, narrow to 

medium, slightly widened distally; corona 0.5 mm long; 

apical hairs sparse to dense, length short to medium; 

embryo about I/5 as long as caryopsis (Figure 8i-m). (*BN 

20815-70, France, SCS, USDA; Vasey 3076, Washington 

state (US).) 

Aegilops cylindrica Host [Triticum cylindricum (Host) Cesati] 

[CD; 2n=28]. Ranges from central Europe and the 

Mediterranean region to central Asia, adventive in North 

America. 

Caryopses: 5.5-8.5 mm long; lanceolate or narrowly 

elliptic; compression dorsiventral, moderate, dorsal face 

somewhat rounded, ventral face flattened; lateral ridges 

none; sulcus shallow, narrow and almost closed, sometimes widened at distal end; corona -1 mm long, 

somewhat like a cap; apical hairs dense, length medium; 

embryo '/3-l/5 as long as caryopsis (Figure 9a-p). (Terrell 

4841, Weber Co., Utah.) 

Comment: Each spikelet has two fertile florets of which 

both or one may produce caryopses. If two are produced, 

they differ in size and sometimes slightly in shape. Two 

pairs of spikelets are drawn, each spikelet with 2 caryopses 

to show the variation. 

Aegilops triuncialis Linnaeus [Triticum triunciale (Linnaeus) 

Raspail] [CU; 2n = 281. Ranges from the Mediterranean 

region to central Asia. 

Caryopses: 6.5-8.5 mm long; lanceolate or narrowly 

elliptic; compression dorsiventral, moderate, dorsal face 

somewhat rounded, ventral face flattened or slightly 

rounded or concave; lateral ridges none; sulcus shallow to 

medium, closed and with a small opening adjacent to 

hilum; corona 0.5- 1.5 mm long, somewhat cap-like; 

apical hairs dense, length short to medium; embryo I/3-l/4 

as long as caryopsis (Figure 10a-h). (PI 276991, 

Afghanistan.) 

Amhlyopyrum muticum (Boissier) Eig [Aegilops mutica Boissier; A. tripsacoides Jaubert & Spach, Triticum tripsacoides (Jaubert & Spach) Bowden] [Z; 2n = 141. Native to 

Asia Minor and Caucasus. 

Caryopses: 3.5-4 mm long; elliptic or oblong; compression 

dorsiventral, moderate or strong, dorsal face rounded, 

ventral face flattened or broadly V-shape; lateral ridges 

none; sulcus shallow, width medium; corona 0.5-1 mm 

long, somewhat cap-like; apical hairs sparse to dense, 

short; embryo l/3 as long as caryopsis (Figure 1Oi-n). 

(*Bot. Exped. Kyoto Univ. 7-1 -4-0, 7-1 -4-C, Turkey 

(US).) 

Triticum monococcum Linnaeus [Crithodium monococcum 

(Linnaeus) Love] [A; 2n = 141. Native in Europe and the 

Mediterranean region to Caucasus and Iran. 

Caryopses: 7.5-9.5 mm long; ovate or elliptic; compression 

none or slight, caryopses circular in transverse section or 

ventral face slightly compressed; lateral ridges none; 

sulcus depth medium to deep, sulcus closed, with a small 

rounded opening adjacent to hilum; corona 1-2 mm long, 

cap-like; apical hairs dense to sparse, length short to long; 

embryo */5-'/3 as long as caryopsis (Figure 1 la-d). (*PI 

94738, cultivated, St. Petersburg, Russian Federation; PI 

168805, cult. in Kansas.) 

Triticum dicoccon Schrank sens. lat. (sens. Tzvelev, 1976:237, 

238) [AB; 2n = 281. Native to the Mediterranean region 

and southwest Asia. 

Caryopses: 9-1 1 mm long; ovate or elliptic; compression 

none, caryopses circular in transverse section or irregularly 

compressed; lateral ridges none; sulcus medium to deep, 

closed, with a small rounded opening adjacent to hilum; 

corona 1-2.5 mm long, cap-like; apical hairs dense, length 

medium to long; embryo I/3-l/4 as long as caryopsis 

(Figure 1 le-h). (*PI 94664 and PI 94613, cultivated in 

Saudi Arabia.) 

Triticum aestivum Linnaeus [ABD; 2n = 421. Bread wheat, the 

type species, is cultivated worldwide. 

Caryopses: 5.5-7.2 mm long; ovate, broadly elliptic, or 

broadly oblong; compression none or slight, caryopsis 
14 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

m 

f 

1 

9 

h 

FIGURE I.-Caryopsis of Criihopsis deiileana (a-d); Hordeiymus europaeus (e-h); and Taeniatherum 

caput-medusae (i-m). Ventral views (a,e,i,m); lateral views (b,j,j); dorsal views (c,g,k). (All scales = 1 mm.) 
NUMBER 83 15 

a 

i 

b 

i 

1 

C 

k 

1 

1 

I m n 

FIGURE 9.--Caryopsis of Aegilops cylindricu (a-p). Ventral views (u,f,i,l); lateral views (b,g, j,m); dorsal views 

(c,h,k.n); transverse sections (d,e,o,p). (All scales = 1 mm.) 
16 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

a 

i 

C 

k 

1 

d e f 

v 

I 

1 

1 

FIGURE lO.-Caryopsis of Aegilops friuncialis (a-h) and Arnhlyopyrrtrn rnuriciun (A). Ventral views (adi); 

lateral views (b,e,j); dorsal views (c,f,k,l); transverse sections (g,h,rn,n). (All scales = 1 mm.) 
NUMBER 83 17 

a b C 

1 

i i 

1 

1 

k 

1 

e f 

1 

1 

1 

n 0 m 

1 

FIGURE 11 .--Caryopsis of Triticum rnonococcurn (a-d); Triricum dicoccon (e-h); Triticum aestivum (i-1); and 

Secale cereole (m-p). Ventral views (u,e,i,m); lateral views (b,j,j,n); dorsal views (c,g,k,o); transverse sections 

(d,h,l,p). (All scales = 1 mm.) 
18 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

circular in transverse section or slightly compressed 

ventrally; lateral ridges none; sulcus deep to medium, very 

narrow or closed, with small rounded space adjacent to 

hilum; corona 0.5-1.5 mm long, cap-like; apical hairs 

dense, short to long; embryo l/3-l/4 as long as caryopsis 

(Figure 1 li-1). (*CI 13448-cv. Gaines; CI 17745-cv. 

Dirkwin.) 

Comment: Descriptions from Bayles and Clark (1954) were 

added to this, but there is much more variation not 

included here. 

Secale cereale Linnaeus [R; 2n = 141. The type species, rye, is 

cultivated worldwide. 

Caryopses: 6-10 mm long; elliptic or oblong; compression 

none, caryopses circular in transverse section; lateral 

ridges none; sulcus depth medium, closed, with a very 

small opening adjacent to hilum; corona 0.5 mm long, 

cap-like; apical hairs sparse and short or absent; embryo 

2/5-1/3 as long as caryopsis (Figure 1 lm-p). (PI 535198- 

cv. Weser, cult. in Canada.) 

Dasypyrum villosum (Linnaeus) Candargy [Haynaldia villosa 

(Linnaeus) Schur] [V; 2n= 141. This species occurs in 

central Europe and the Mediterranean region to southwest 

Asia. 

Caryopses: 3.8-7 mm long; oblong or elliptic, variable in 

shape; compression lateral, slightly to strongly compressed; lateral ridges none; sulcus shallow, medium or 

narrow to closed; corona 0.5-1.5 mm long, forming an 

angled cap, the two style bases sometimes persistent; 

apical hairs sparse and short or absent; embryo '/4 as long 

as caryopsis (Figure 12a-d). (*C. Chapman s.n., Jul 1984, 

Rome, Italy, via USDA; PI 368886, Turkey.) 

Heteranthelium piliferum (Banks & Solander) Hochstetter [Q; 

2n = 141. Occurs in the eastern Mediterranean region and 

central Asia. 

Caryopses: 5-7.5 mm long; oblong in dorsal view, elliptic in 

lateral view; compression lateral, moderate, dorsal face 

rounded, ventral face somewhat flattened or broadly 

V-shape; lateral ridges none; sulcus medium to deep, very 

narrow or closed, with small rounded opening adjacent to 

hilum; corona 1- 1.5 mm long, cap-like; apex of caryopsis 

obtuse or with two acuminate style bases; apical hairs 

sparse to dense, short, or absent; embryo l/3-l/4 as long as 

caryopsis (Figure 12e-i). (*Bot. Exped. Kyoto Univ. 

5-28-1-C, Iraq (US); Bornmuller 1678, Syria (US); PI 

401 351, Iran.) 

Comment: Caryopses appear to be somewhat heteromorphic. 

Henrardia persica (Boissier) C.E. Hubbard [O; 2n = 141. This 

type species occurs in the eastern Mediterranean region to 

central Asia. 

Caryopses: 4.8-6.2 mm long; lanceolate or oblong; compression dorsiventral, moderate to strong, dorsal face 

flattened or slightly concave, ventral face concave to 

rounded; lateral ridges none; sulcus very shallow, narrow 

to medium; corona 0.2-0.5 mm long, cap-like?; apical 

hairs sparse to dense, short; embryo */3 as long as caryopsis 

(Figure 12j-m). (*Mokeeva 522 Tian-schan, central Asia 

(K); PI 401347-9, Iran.) 

Brachypodium pinnatum (Linnaeus) P. Beauvois [2n = 281. 

The type species is native in Europe, southwest Asia, and 

northwest Africa. 

Caryopses: 6-7 mm long; lanceolate or oblong; compression 

dorsiventral, moderate, dorsal face rounded or somewhat 

flattened; lateral ridges none; sulcus depth medium, width 

wide; corona 0.5 mm long; apical hairs dense, short; 

embryo '/s-'/6 as long as caryopsis (Figure 12n-q). (PI 

251803, Italy.) 

Discussion 

The characters showing significant differences among 

genera have been tabulated for comparison (Table 2). The 

shared characteristics of the caryopses have lead us to 

recognize the following three groups: elymoid, triticinoid, and 

henrardioid. A fourth entity is Brachypodium, which according 

to our data remains controversial. The previously recognized 

limits of the subtribe Triticinae are indistinct and inconsistent 

as used by various authors (e.g., Tzvelev, 1976), and they do 

not coincide with the limits we recognize on the basis of 

caryopsis structure. 

ELYMOID GROUP.-The elymoid group examined in this 

study includes Elymus, Elytrigia, Leymus, Psathyrostachys, 

Agropyron, Eremopyrum, Hordeum, Crithopsis, Hordelymus, 

and Taeniatherum. 

The elymoid caryopsis characters are as follows: caryopses 

2.5- 1 1 mm long, not heteromorphic, although sometimes 

differing slightly in size within one spikelet; caryopses usually 

oblong, oblanceolate, lanceolate, or elliptic; compression 

dorsiventral (slight-) moderate to strong, flattened more on 

ventral face than on dorsal; lateral ridges absent or rudimentary, 

large in Crithopsis, Taeniatherum, and Hordelymus; sulcus 

depth shallow to medium, width (narrow-) medium to wide, 

often widened distally; corona a thin whitish or yellowish 

flattened apical membrane, usually bearing apical hairs; apical 

hairs usually dense (-sparse), (short-) medium to long; 

embryo ('/3-) '/4-'/5 (-'/6) as long as caryopsis. 

Two of the species included in Elymus traditionally were 

placed in Hystrix and Sitanion: E. hystrix (Hystrix patula) and 

E. elymoides (Sitanion hystrix). Sitanion was treated in a 

traditional sense by Wilson (1963). Church (1967a,b) advocated the union of Hystrix and Elymus after finding natural 

hybrids between them. Dewey (1982, 1984:246-250) and 

Love (1984:447) united both Hystrix and Sitanion in Elymus, 

Love recognizing them as sections. Clayton and Renvoize 
NUMBER 83 19 

1 

C 

r 

a b 

k 

1 

I 

- 

.. 

e 

n 

f 

1 

0 P 

9 

q 1 

RGURE 12.-Caryopsis of Dasypyrum villosum (a-d); Hereranthelium piliferum (e-i); Henrardia persica 

(j-m); and Brachypodium pinnatum (n-9). Ventral views (a,e, j,n); lateral views (b,f,k,o); dorsal views (c,g.l,p); 

transverse sections (d,h,i,m,q). (All scales = 1 mm.) 
20 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

TABLE 2.-Morphological variation in selected characters. (Abbreviations as follows: abs = absent; cap = 

cap-like; clos = closed: dv = dorsiventral: dvvf = dorsiventral with ventral face flattened; n. = narrowly; ell = 

elliptic; lat = lateral; lanc = lanceolate; med = medium; mod = moderate; narr = narrow; oblanc = oblanceolate; 

rud = rudimentary; shal = shallow; slt = slight: str = strong: vert = vertical.) 

Species 

Elymus sibiricus 

E. dahuricus 

E. caninus 

E. hystrix 

E. elymoides 

E. distichus 

Elyfrigia repens 

E. elongata 

E. spicafa 

Leymus arenarius 

L. angusfus 

L. alaicus 

Psathyrostachys juncea 

P. fragilis 

Hordeum bogdanii 

H. jubatrtm 

H. sponfaneum 

H. disfichon 

H. vulgare 

Agropyron cristatrrm 

Eremopyron triticeum 

Cri fhopsis delileana 

Hordelymus europaeus 

Taeniatherum caput-medusae 

Aegilops cylindrica 

A. triuncialis 

Amhlyopyron muticum 

Triticum monococcum 

7: dicoccon 

T. aestivum 

Secale cereale 

Dasypyron villosum 

He feranthelium piliferum 

Henrardia persica 

Brachypodiurn pinnatum 

Compression Sulcus 

Shape Extent Depth Depth Width Ridge Corona 

oblanc/oblong 

n 

lanc/n. ell 

oblong 

oblongh. ell 

oblanc/oblong 

oblongflanc 

oblong 

oblanc/oblong 

oblong 

oblongflanc 

oblanc/ell 

n. ell 

ell 

elVovate 

oblongflanc 

lanc/ovate 

lanc/n. ell 

n. lanc 

lanc/n. ell 

ell/oblong 

ovate/ell 

oblonglell 

lanc/oblong 

dv 

n 

n 

N 

dvvf 

noneklt 

none 

none/slt 

none 

lat 

dv 

mod 

mod/str 

slt 

mod 

modstr 

mod 

mod/str 

mod 

slt 

slt/none 

slt 

str 

mod 

mod/str - 

- 

- 

- 

slt/str 

mod 

modstr 

shal 

s haumed 

med/deep 

shal/med 

shal 

med 

med 

shdmed 

med 

deep 

shal/med 

shal 

shaUmed 

med 

med/deep 

shal 

s hal/med 

shal 

med/deep 

deep 

med 

shal 

med/deep 

shal 

med 

mewwide n 

wide 

med 

medwide 

wide 

med/wide 

mewwide 

medlwide 

med 

wide 

narr/med 

narrlmed 

nardwide 

med 

narr/med 

narr/clos 

clos 

med 

clos 

n 

n 

med/clos 

clos 

narr/med 

wide 

abs 

n 

n 

n 

rudabs 

rud 

ruaabs 

rud 

abs 

small 

abs 

n 

n 

n 

large 

n 

abs 

n 

n 

n 

n 

vert 

n 

I* 

n 

n 

n 

n 

n 

n 

n 

n 

cap 

n 

n 

cap? 

vert 

(1986:151, 152) recognized Hystrix and Sitanion as good 

genera and included Cockaynea Zotov from New Zealand in 

Hystrix. Differences among the caryopses of E. hystrix, E. 

elymoides, and the other Elymus species with an SH genome 

are minor, although E. elymoides and E. hystrix have distinct 

morphological differences in other characters, such as inflorescence structure and glume shape and length. In view of the 

latter differences, we believe that Hystrix and Sitanion, 

although obviously closely related to Elymus, deserve further 

study before being subsumed in Elymus. 

There are other minor differences among Elymus species 

having the SH genome. Elymus dahuricus and E. caninus have 

caryopses in which the sulcus widens distally (Figure 2e,i), 

whereas in other species of Elymus the sulcus is equally wide 

near the base and apex of the caryopsis. This state is not 

peculiar to genera with the SH genome as it also is found in 

Elytrigia and Leymus. 

Elymus distichus, traditionally in Agropyron, was placed in 

Elymus sect. Junceae (Prat) Melderis by Melderis (1978b) and 

in Thinopyrum by Love (1984). It has the J or JE genome. The 

caryopses are unusually large and strongly compressed for 

Elymus and are distinctive in having a large, broad, somewhat 

auriculate corona sparsely beset with short hairs (Figure 3e). 

This species differs from other species of Elymus and deserves 

further study along with other members of sect. Junceae. 

The three species of Elytrigia examined have an SX genome 

(E. repens), an E genome (E. elongata), and an S genome (E. 

spicata); however, the species do not differ in any distinctive 

characteristics. The caryopses of Elytrigia repens (Figure 3i-I) 

are less compressed and have a narrower sulcus than those of E. 
NUMBER 83 

spicata (Figure 4a-d). The caryopses of Elytrigia elongata 

(Figure 3m-p) are similar to the other species of Elymus 

examined. 

Psathyrostachys fragilis is morphologically distinct from the 

other species of the genus (Baden, 1991) in having readily 

disarticulating spikelets with very long awns. The examined 

species of Psathyrostachys and Leymus have similar caryopses 

(Figures 4e-1, 5a-f), spikelets, and florets (e.g., compare 

spikelets and florets of Leymus cinereus (Scribner & Merrill) 

Love and Psathyrostachys junceus). Their genomes also 

indicate a close relationship, as Psathyrostachys contains the N 

and Leymus the JN genomes. 

In summary, caryopses of the 14 examined species of 

Elymus, Elytrigia, Leymus, and Psathyrostachys generally are 

similar in morphology. There does not seem to be any 

particular set of character states that occur in one genome or 

genus and not in others; e.g., caryopses of Elymus caninus, 

Elytrigia elongata, and Leymus alaicus subsp. karataviensis 

are very similar. Elytrigia repens and Psathyrostachys fragilis 

are somewhat similar, as are Elymus sibiricus and Leymus 

arenarius. The caryopses of Leymus and Psathyrostachys are 

similar in all the species sampled. If there are character states 

hidden within the caryopsis that are characteristic or predominant within any particular genome, a much larger sampling of 

a range of species would be necessary to reveal them. We 

conclude that similarities among caryopses of the four genera 

are more significant than the minor differences found in this 

study. Based on caryopsis morphology our results suggest that 

Elytrigia, Leymus, and Psathyrostachys might be included in a 

broad genus Elymus, a course espoused by Estes and Tyrl 

(1982). 

Hordeum, with its characteristic triads or groups of three 

spikelets, is a fully distinct genus. Bothmer et al. (1984) 

recognized four sections in Hordeum. These are represented in 

the present study: sect. Hordeum by H. spontaneum, H. 

distichon, and H. vulgare; sect. Anisolepis by H. pusillum 

(SEM photo only); sect. Critesion by H. jubatum; and sect. 

Stenostachys by H. bogdanii. Love (1984:436-441) placed the 

latter two species in a separate genus, Critesion. Caryopses of 

Hordeum bogdanii and H. jubatum (Figure 5i-p) are similar to 

each other and to species of Elymus (Figures 2a-4, 3a-h). 

Hordeum spontaneum, H. distichon, and H. vulgare (Figure 

6a-n) have similar caryopses, but differ from H. bogdanii and 

H. jubatum (Figure 5i-p); consequently, there appears to be 

two groups based on the caryopses characters. The caryopsis 

evidence seems to suggest that Hordeum sect. Hordeum is a 

distinct entity, whether section, subgenus, or genus (true 

Hordeum), but certainly caryopses of additional species need to 

be studied. We are unsure as to the distinctiveness of Critesion 

from Hordeum, as our limited sample does not allow 

speculation. 

The crested wheatgrass complex is morphologically distinct 

from the traditional Agropyron species now shifted to Elymus. 

The caryopsis of Agropyron cristatum (Figure 7a-h) differs 

21 

from the illustrated species of Elymus by having only slight 

dorsiventral compression, a deeper and narrow or mediumwide sulcus, and shorter apical hairs. Although the systematic 

relationships of Eremopyrum (Frederiksen, 199 1 b) have been 

controversial, Bowden (1962) and Clayton and Renvoize 

(1986:155) suggested that the genus is closely related to the 

Agropyron cristatum group. We agree with this assessment 

because the inflorescence, spikelets, florets, and caryopses 

resemble those of A. cristatum (Figure 7i-4). 

Crithopsis and Hordelymus are monotypic genera with 

caryopses having rather strong ventral compression, a deep and 

rather wide sulcus, conspicuous lateral ridges, and similar 

coronas (Figure 8a-h). The caryopses of Taeniatherum are less 

strongly compressed, have a medium-deep and medium-wide 

sulcus, and conspicuous lateral ridges (Figure 8i-m). These 

three genera possess similar caryopses and seem to be 

somewhat distinct from the other elymoid genera. 

TRITICINOID GROUP.-The triticinoid group includes Aegilops, Amblyopyrum, Triticum, Secale, Dasypyrum, and Heteranthelium. 

The triticinoid caryopses characters are as follows: caryopses 

4-11 mm long; lanceolate or oblong to elliptic or ovate; 

compression none, or flattened dorsiventrally only on the 

ventral side, or slightly to strongly flattened laterally; sulcus 

depth varying from shallow to deep; sulcus width very narrow 

or closed; corona cap-like; apical hairs dense or often sparse, 

length short or medium, hairs sometimes lacking in Dasypyrum, Heteranthelium, and Secale; embryo (*/5-) I/3-I/4 (-l/5) 

as long as caryopsis; caryopses slightly or somewhat heteromorphic (differing in size and shape in florets from the same 

spikelet) in Aegilops, Dasypyrum, and Heteranthelium. 

Aegilops and Triticum are sometimes united (e.g., Bowden, 

1959), maintained as distinct (e.g., ntin and Humphries, 

1980), or divided into several genera (Love, 1984:491-498). 

The caryopses of Aegilops cylindrica and A. triuncialis 

resemble one another by having ventrally flattened caryopses 

with shallow sulci (Figures 9, 10a-h). The caryopses of 

Triticum conspicuously differ from these species of Aegilops 

by being ventrally rounded with medium to deep sulci with a 

small open area adjacent to the hilum (Figure lla-1). 

However, the caryopses of Aegilops ovata Linnaeus and A. 

umbellulata Zhukovsky (not illustrated) show resemblances to 

wheat. On account of the few species studied, we cannot 

provide any definite conclusions on the degree of interrelationships between Aegilops and Triticum. 

Aegilops cylindrica, A. triuncialis, and other species in the 

genus usually have two fertile florets per spikelet. The two 

resulting caryopses present in the spikelet differ in size and to 

a lesser degree in shape (Figures 9a-p, 1Oa-h). Caryopsis 

differences within a spikelet also were seen (not illustrated) in 

A. squarrosa Linnaeus (collection USDA CI 8) where one 

floret contained a caryopsis 5.8 mm long x 3.2 mm wide, 

whereas the other floret bore a caryopsis 5.2 mm x 3.2 mm. 

Another spikelet contained caryopses 5.6 mm long x 3.1 mm 
22 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

wide and 5.0 mm long x 3.0 mm wide. This heteromorphism or 

heterocarpism in the two caryopses of one spikelet is perhaps 

uncommon in grasses or at least inadequately documented, 

although any grass species with several florets per spikelet may 

have caryopses that differ slightly in size within the same 

spikelet (e.g., Lolium and Festuca). 

Amhlyopyrum muticum was treated as distinct from Aegilops 

by several authors (e.g., Bor, 1968:224-226; Tzvelev, 

1976:219, 220). Its caryopses differ somewhat from the two 

species of Aegilops illustrated here in shape and in having a 

wider sulcus (Figure 1Oi-n). 

Triticum monococcum and T dicoccon, wild relatives of 

wheat, have caryopses that are almost identical (Figure 1 la-h). 

Their caryopses are not compressed but are rounded in 

transverse section and have a deep, closed sulcus. Triticum 

aestivum (wheat) has shorter, broader, and more ovate 

caryopses (Figure 1 li-1). Triticum aestivum and Secafe 

cereafe (rye) caryopses are basically similar in transverse 

section and differ mainly in size and shape (Figure llm-p). 

The similarity in caryopsis morphology between Triticum and 

Secale is consistent with their known genetic compatibilities in 

crossing successfully to produce the hybrid triticale. 

Dasypyrum viflosum (Figure 12a-d) is distinctly set off 

from Triticum (Figure lla-f) by having slightly to strongly 

compressed caryopses with a corona forming an angled cap 

usually with persistent style bases. However, the characteristics 

of the inflorescence, spikelet, and to some extent the caryopsis 

align Dasypyrum with the triticinoid group. It also is known to 

hybridize with Triticum (Frederiksen, 199 1 a). Heteranthelium 

piliferum (Figure 12e-i) has certain distinctive characters, such 

as a strongly laterally compressed caryopsis with a rather deep 

sulcus and apical acuminate style bases, but the caryopsis has 

obvious resemblances to Triticum and Dasypyrum. 

HENRARDIOID GROUP.-The henrardioid group includes 

only Henrardia, an anomalous genus whose systematic 

position has been controversial. The two species of Henrardia 

formerly were placed in Pholiurus or Lepturus (now in tribe 

Hainardieae according to Tutin, 1980) until Hubbard (1946) 

created the new genus Henrardia and placed it in the Triticeae 

(as Hordeae) on the basis of lemma nervation, lodicules, 

ovaries, and caryopses. The genus sometimes has been placed 

in its own subtribe, Henrardiinae Hubbard in Hook. 

Caryopses of Henrardia persica resemble other Triticeae in 

having a linear hilum, a corona with apical hairs, and a sulcus 

(Figure 12j-m). They are like the elymoid genera in having a 

generally lanceolate or oblong shape and rather strong 

dorsiventral compression (Figures 2, 3a-h). However, the 

caryopses are unusual in having a particular combination of 

characteristics not found in any other members of the Triticeae. 

The dorsal and ventral faces of the caryopses are equally 

compressed with a very shallow, narrow sulcus, its margins low 

and rounded (unlike the elymoid species), and a small corona 

with apical hairs usually sparse and short (Figure 12j-m). 

Clayton and Renvoize (1986:158) noted that Henrardia 

although seemingly aberrant is not far removed from Aegilops 

sect. Vertehrata (A. ventricosa Tausch). Our sampling of 

Aegilops species is insufficient to test this opinion. Henrardia 

appears to belong in the Triticeae and its caryopsis morphology 

suggests that it represents a distinct subtribe. 

BRACHYPODIUM GROUP.-Brachypodium is a genus of 

controversial alliances, placed in the Triticeae by Clayton and 

Renvoize (1986: 148-150) but most often treated in its own 

tribe, Brachypodieae Hackel, or considered close to the 

Bromeae (Macfarlane and Watson, 1982). The caryopses of 

Brachypodium pinnatum (Figure 12n-q) are somewhat similar 

to elymoid species (Figures 2, 3a-h) in shape and sulcus 

morphology. This species has a chromosome number of 

2n = 28, which agrees with the basic number of 7 for the tribe. 

Other species of Brachypodium differ in chromosome number 

and have been found to possess base numbers of 5 and 9 

(2n = 38), thus suggesting that Brachypodium as traditionally 

constituted is heterogeneous. We examined caryopses of two 

other species (not illustrated), B. syfvaticum (Hudson) P. 

Beauvois [Brevipodium sylvaticum (Hudson) A. & D. Love] 

with x = 7, 9 (Veldkamp and van Scheindelen, 1989) and B. 

distachyon (Linnaeus) P. Beauvois [Trachynia distachya 

(Linnaeus) Link] with 2n = 28 or 30. Both of these species have 

caryopses generally similar to those of B. pinnatum. The 

caryopses of Brachypodium also resemble those of Bromus 

(Bromeae). Based on chloroplast DNA restriction site variation 

within the Pooideae, Soreng et al. (1990) found that Brachypodium pinnatum, Bromus inermis Leysser, and Hordeum 

vulgare always formed a clade representing the supertribe 

Triticodae. Based on the phytochemical characters Veldkamp 

and van Scheindelen (1989) stated that Brachypodium differs 

from the Triticeae and Bromeae. We are uncertain whether 

Brachypodium belongs in this tribe, considering the conflicting 

evidence and its similarity in caryopsis structure to Bromus and 

the Bromeae. 

tion to the characters we employed to analyze triticoid 

variation, there are other characters that are characteristic for 

the Triticeae as a whole that sometimes distinguish this tribe 

from certain other tribes (Terrell, unpublished). We take this 

opportunity to summarize these here and also to include the 

embryo characters studied intensively by Reeder (1957). The 

caryopses of the Triticeae have the following principal tribal 

diagnostic characteristics: (1) caryopses relatively large, 2.5- 

11 mm long in taxa studied; (2) compression in the elymoid and 

henrardioid genera and Brachypodium usually moderately to 

strongly dorsiventral, sometimes unequal on dorsal and ventral 

faces; in triticinoid genera compression lacking or lateral or 

somewhat dorsiventral; (3) caryopses with an open or wide 

sulcus in elymoid and henrardioid genera, narrow or closed in 

triticinoid; (4) hilum linear, often black or dark, lying in the 

sulcus, almost as long as caryopsis; (5) corona a thin 

membranous appendage, whitish, cream, or yellowish, flattened dorsiventrally and extending vertically above the 

CARYOPSES CHARACTERISTICS OF THE TRITICEAE.-In addi- 
NUMBER 83 23 

caryopsis apex, or in triticinoid genera covering the apex 

horizontally like a cap; (6) apical hairs borne on the corona, 

sparse to dense, short to long; corona and hairs usually 0.5-1 or 

1.5 mm long, or hairs absent in certain species; (7) embryo 

(*/s-) '/3-l/5 (-l/6) as long as caryopsis; (8) endosperm solid, 

but not very hard; (9) caryopses heteromorphic (varying in size 

or shape in one spikelet) in Aegilops, Dasypyrum, Heteranthelium, and perhaps Triticum; (1 0) two-branched style relatively 

short, usually broken off in mature caryopses; (11) embryo 

formula F + FF or F - FF (Reeder 1957); and (12) lemma and 

palea usually tightly attached to caryopsis. 

Conclusions 

The Triticeae can be divided into two major subtribes and 

one monogeneric subtribe (Table 3). The genera within the 

triticinoid group exhibit similar caryopses features among the 

species as do the genera in the elymoid group. The genera in 

these subtribes vary with the opinions of the botanists studying 

them (e.g., Runemark and Heneen, 1968; Sakamoto, 1973). 

Our opinion on the composition of these subtribes rests on our 

interpretations of the caryopsis morphology and the inclusion 

of other types of data. 

The main differences between elymoid and triticinoid groups 

may be summarized in the form of a key: 

TABLE 3.4lassification for genera examined. Nomenclatural citations follow 

Clayton and Renvoize (1986). 

Tribe: TRITICEAE Dumortier, Obs. Gram. Belg. 82. 1824. 

Subtribe 1: TRITICINAE Grisebach, Fl. Rumel. Bithyn. 2:422. 1844. 

Type: Triticum Linnaeus 

Genera: Aegilops 

Amhlyopyrum 

Dasypyrum 

Heteranthelium 

Secale 

Triticum 

Subtribe 2: HORDEINAE Dumortier, Obs. Gram. Belg. 91. 1824. 

Type: Hordeum Linnaeus 

Genera: Agropyron 

Crithopsis 

Elymus 

Elytrigia 

Eremopyrum 

Hordelymus 

Hordeum 

Leymus 

Psathyrosiachys 

Taeniutherum 

Subtribe 3: HENRARDIINAE C.E. Hubbard in Hooker, Ic. PI. 35. t. 3453. 

1948. 

5pe: Henrardia C.E. Hubbard 

Uncertain alignment: Brachypodium 

Caryopses dorsiventrally compressed; often lanceolate, oblong, or oblanceolate; sulcus 

usually wide, occupying I/z or more of the ventral face or narrow at the base and 

widened distally; corona a short projecting appendage at apex of caryopses, often with 

dense, medium to long apical hairs; embryos often about l/4 as long as caryopses ... ...................................... Elymoid Group 

Caryopses not compressed (round in transverse section) or laterally compressed or 

dorsiventrally compressed only ventrally in Aegilops and Amhlyopyrum; often ovate or 

elliptic; sulcus narrow or closed; corona covering the apex like a horizontally flattened 

cap, often with sparse hairs or lacking hairs; embryos often l/3 as long as caryopses . . ..................................... Triticinoid Group 

We conclude that non-embryo characters of the Triticeae 

provide significant systematic data. We establish the existence 

of two distinct groups of genera in the Triticeae, here Elymus. 

recognized as subtribes Hordeinae and Triticinae (Table 3). 

Within the Hordeinae our data support a broad delimitation of 
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