SMITHSONIAN CONTRIBUTIONS TO BOTANY NUMBER 85 

The Silica Bodies of Tropical 

American Grasses: Morphology, 

Taxonomy, and Implications 

for Grass Systematics and 

Fossil Phytolith Identification 

Dolores R. Piperno 

and Deborah M. Pearsall 

SMITHSONIAN INSTITUTION PRESS 

Washington, D.C. 

1998 
ABSTRACT 

Pipemo, Dolores R., and Deborah M. Pearsall. The Silica Bodies of Tropical American 

Grasses: Morphology, Taxonomy, and Implications for Grass Systematics and Fossil Phytolith 

Identification. Smithsonian Contributions to Botany, number 85,40 pages, 76 figures, 2 tables, 

1998.-Silica bodies from over 200 species of Neotropical grasses comprising 80 different 

genera from all currently recognized subfamilies have been isolated from plant tissue and have 

been described. Silica-body shapes are significant at varying taxonomic levels, from the family 

to the genus. The Bambusoideae, especially, contribute large numbers of tribal- and 

genus-specific forms. Significant correlations are found between phytolith shape and the source 

plant’s taxonomic relationships and postulated phylogeny. Disarticulated short-cell phytoliths 

occumng in ancient soils and sediments can be used to make identifications of certain taxa in the 

Poaceae below the level of family. Silica bodies observed in fossil grasses may elucidate the 

evolutionary history of the Poaceae. 

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. SERIES COVER 

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

Library of Congress Cataloging-in-Publication Data 

Pipemo, Dolores R. 

fossil phytolith identification / Dolores R. Pipemo and Deborah M. Pearsall. 

Includes bibliographical references @. 8). 

1. Grasses-Latin America-Classification. 2. Grasses-Latin America-Cytology, 3. Grasses, FossilIdentification. 4. Silica bodies (PlantsFLatin America. I. Pearsall, Deborah M. 11. Title. 111. Series. 

QKI.S2747 no. 85 [QK495.G74] 580 s-dc21 [584‘.9’098] 97-2271 1 

The silica bodies of tropical American grasses : morphology, taxonomy, and implications for grass systematics and 

p. cm.-(Smithsonian contributions to botamy : no. 85) 

@# 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 

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

Sampling Methods ................................... 2 

General Patterns at the Subfamily Level ......................... 2 

Examples of Phytolith Discrimination at and below the Subfamily Level ...... 3 

Phytoliths with Limited Distributions in the Poaceae ................. 4 

Other Kinds of Silica Bodies and Patterns of Silicification .............. 4 

Other Important Phytoliths not Derived from Short Cells ............... 5 

Summary ......................................... 5 

Grass Taxon Identification and Environmental Reconstruction from 

Phytoliths Retrieved from Ancient Tropical Soils and Sediments ......... 5 

The Place of Phytoliths in Paleoagrostology and Grass Systematics ......... 6 

Literature Cited ...................................... 8 

Tables .......................................... 10 

Figures .......................................... 22 

... 

111 

The Silica Bodies of Tropical 

American Grasses: Morphology, 

Taxonomy, and Implications 

for Grass Systematics and 

Fossil Phytolith Identification 

Dolores R. Piperno 

and Deborah M. Pearsall 

Introduction 

Silica bodies are a type of phytolith that form in specialized 

epidermal cells of grass leaves. They have long been 

recognized as distinctive to the Poaceae (Grob, 1896; Prat, 

1936; Blackman, 197 1). Various workers have considered 

silica bodies to be diagnostic to family, and often they reflect 

the plants’ subfamily affilations (Twiss et al., 1969; Brown, 

1984; Mulholland, 1989). In paleoecological and archaeological sequences from North America, silica bodies have provided 

information on past environments and human subsistence, 

having been recovered in a virtually unaltered state from 

sediments up to 600,000 years old (Fredlund, 1986; Mulholland, 1993). They also have been recognized in fossilized 

remains of grasses dating to the Miocene where, in conjunction 

with other micromorphological characters of the leaf, they have 

provided information on the fossil’s phylogeny and taxonomic 

relationships (Thomasson, 1984, 1987; Thomasson et al., 

1986). 

Although well established as significant and taxonomically 

important components of grasses, phytoliths rarely have been 

used independently either to positively identify specific taxa or 

to elucidate grass phylogeny. The prevailing assumption has 

been that grasses produce a limited range of silica-body shapes, 

which, at any rate, too often demonstrate overlap from 

Dolores R. Piperno, Smithsonian Tropical Research Institute, Box 

2072, Balboa, Panama (mailing address: STRI Unit 0948, APO AA 

34002-0948). Deborah M. Pearsall, Department of Anthropology, 

American Archaeology, University of Missouri, Columbia, Missouri 

6521 1. 

subfamily to subfamily to be of critical use in the systematics 

and evolution of the Poaceae (Thomasson, 1987; but see 

Muholland, 1989, and Ollendorf et al., 1988). 

Compared to research carried out in temperate regions, far 

fewer studies involving grass phytoliths have been attempted in 

the Old and New World tropics (Piperno, 1988; Pearsall, 1989). 

As the Poaceae may have had its origins in moist tropical or 

subtropical lowlands (Stebbins, 1986), and as there has been a 

heightened interest in the determination of natural and human 

effects on lowland tropical environments during the Quaternary 

period (Leyden, 1987; Leyden et al., 1993; Piperno et al., 1990, 

199 l), the availability of phytolith keys with broad application 

to the grass family will become increasingly important in 

botanical research. 

We have completed the first major survey of silica bodies in 

New World tropical grasses. Our goals were two-fold: (1) to 

provide a key to the kinds and distributions of short-cell 

phytoliths in the tropical American flora that will be of use in 

plant systematics and paleobotany, and (2) to determine to what 

extent identification of grass subfamilies, tribes, and genera can 

be made from individual phytoliths retrieved from ancient soils 

and sediments in Central and South America. 

Our results indicate that certain kinds of silica bodies may be 

found in all of the subfamilies of the Poaceae and they can be 

used for discrimination below the family level only with 

caution. However, other short-cell phytoliths disarticulated 

from plant tissue are valid indicators of individual subfamilies, 

tribes, and genera of grasses, and these do provide valuable 

information on grass taxonomy and phylogeny. 

1 
2 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

ACKNOWLEDGMENTS.-This research was supported by a 

grant to the authors from the National Science Foundation 

(BNS-89-2365), the Smithsonian Tropical Research Institute 

(STRI), and a grant to the STRI from the Andrew W. Mellon 

Foundation. Part of the work was camed out at The Museum 

Applied Science Center for Archaeology (MASCA), University of Pennsylvania, which Piperno thanks for its generous 

support. 

SAMPLING METHODS 

Leaves, culms, and inflorescences from over 200 species of 

grasses comprising 80 different genera and representing a 

broad survey of all five subfamilies now recognized (Watson et 

al., 1985; Kellogg and Campbell, 1987) were studied. 

Assignation of individual genera to subfamily and tribe 

followed the current consensus in grass systematics (Soderstrom et al., 1987). Most of the species analyzed were sampled 

from annotated herbarium sheets at the Missouri Botanical 

Garden (in St. Louis and housed at the Smithsonian Tropical 

Research Institute, Panama) and the National Herbarium in 

Washington, D.C. A few species were collected in the field by 

the authors during field trips made to Latin America over the 

past 15 years. 

For most species under consideration, at least two replicate 

specimens derived from different, local populations were 

analyzed. As bamboos inhabit a wide range of habitats and may 

constitute a significant component of the tropical flora, our 

sample included representatives of almost every genera and 

many species of the Bambusoideae reported from the Neotropics (Soderstrom and Ellis, 1987). 

Phytoliths were extracted from plant material by the wet 

oxidation method described in Piperno (1988) and were 

mounted on slides in Permount, a histological fixative. 

A multitude of short-cell phytolith types were isolated from 

the grasses analyzed. Many of them have not been reported 

previously in studies of North American and European grasses 

(e.g., Parry and Smithson, 1964, 1966; Twiss et al., 1969; 

Brown, 1984; Mulholland, 1989). This paper will discuss and 

illustrate the major distributional patterns demonstrated by the 

phytolith types, concentrating on those forms considered to be 

diagnostic of grasses below the family level, as well as on the 

forms that appear to be repeated often across major boundaries 

of the family. 

General Patterns at the Subfamily Level 

Table 1 summarizes the distribution of the short-cell 

phytoliths isolated from the grasses studied. Silica bodies 

classified as circular to oval- (rondels), saddle-, bilobate-, or 

cross-shaped are well-established diagnostic features of the leaf 

epidermis, occurring both over and between the leaf veins. This 

study shows that they also may be conspicuous components of 

the epidermis of inflorescence bracts, culms, and seeds, 

although the latter two structures often have a very low 

phytolith content and usually contribute other types of 

phytoliths. 

In Table 1, the placement of phytoliths under the saddle-, 

rondel-, bilobate-, or cross-shaped category signifies that these 

bodies are of the classic shapes that have been commonly 

reported in previous grass studies. In other words, they are 

usually tabular, mirror-image forms that almost always assume 

saddle-, bilobate-, or cross-like orientations when observed in 

tissue and also when removed from plant parts and mounted on 

slides as separate entities. 

In this study, many variations of these conventional, 

short-cell phytoliths were observed. Such phytoliths typically 

had only a single developed saddle- or bilobate-like face, and, 

as originally formed in the plant, they were thick with relatively 

deep extensions into the epidermal tissue. When removed from 

the plant and placed on slides they turned and assumed various 

kinds of wide, irregular shapes, with the saddle or bilobate face 

that had been observed in tissue becoming more difficult to 

define because it had become one of the lateral edges of the 

phytolith. In Table 1, these phytoliths were given either their 

own categories or were placed in the “Other” category. Most 

are described and illustrated. 

Twiss et al. (1969) proposed three major divisions of 

short-cell phytoliths corresponding to three dominant subfamilies native to the Great Plains of the United States: bilobate/ 

cross = Panicoideae, saddle = Chloridoideae, and circulariovall 

rectangular = Pooideae. They recognized that some deviation 

from this typology occurred; for example, circular to oval 

bodies were observed in some panicoid grasses. Brown (1 984) 

and Mulholland (1989) carried out more extensive studies of 

North American grasses and also found that although the 

three-part division generally held, there were significant 

deviations from the expected pattern. The same was true of the 

tropical grasses studied herein. 

Circular to oval phytoliths or “rondels” (Mulholland, 1989), 

which are most closely associated with the Pooideae (Table l), 

also are found in the Arundinoideae, Panicoideae, and, most 

prominently, in the inflorescences of the Bambusoideae 

(Figures 1-4, Table 1). Bilobate phytoliths, the most characteristic markers of the Panicoideae (Table l), also are present in 

the Arundinoideae, Pooideae, Bambusoideae, and Chloridoideae (Figures 5- 15). Indeed, bilobates are the most common 

kind of silica body in phytolith assemblages from certain 

genera in these subfamilies, such as Aristida (Arundinoideae), 

Eragrostis (Chloridoideae), and Stipa (Pooideae). The crossshaped phytolith, another panicoid marker, is common in 

certain Bambusoideae (tribe Olyreae) (Table 1) and occurs in 

small numbers in the Chloridoideae, Arundinoideae, and 

Pooideae (Brachypodium, Polypogon) (Figures 16, 17). 

Saddle-shaped phytoliths are the dominant phytolith class of 

the Chloridoideae (Table 1). They are also common in two 

subtribes of the Bambusoideae (Guaduinae and Chusqueinae) 
NUMBER 85 

(Table 1) and are present in two genera of the Arundinoideae 

(Aristida, Phragmites) (Figures 1 8-22). 

Individual genera in the Arundinoideae are marked by highly 

divergent sets of phytoliths that may exhibit Panicoideae, 

Chloridoideae, or Pooideae tendencies (Table 1). Phytoliths 

with both saddle and bilobate tendencies, called “saddle/ 

bilobates,” are common in this family, whereas the conventional kinds of saddle and rondel forms are relatively rare. 

These determinations are consistent with findings that the 

Arundinoideae is actually a hetereogeneous and poorly defined 

group of loosely related genera (Conert, 1987), and with the 

current belief that this subfamily is primitive and basal to all 

others of the Poaceae (Kellogg and Campbell, 1987). 

It is evident from this analysis that the assignation of 

short-cell phytoliths found in ancient sediments and fossil 

plants to a particular grass subfamily will not always be 

possible. Compounding the difficulty is that several different 

plant structures may contribute confuser phytoliths. For 

example, rondels may be found in both the leaves and 

inflorescences of Aristida, whereas saddles occur in leaves, 

culms, and inflorescences of bamboos. However, a large 

number of other short-cell phytoliths that were observed in this 

study do appear to be both disjunct in distribution and 

diagnostic at and below the subfamily level. Some of them need 

to be isolated from plant tissue for proper study. Many have not 

been described previously in other phytolith studies. A 

summary of these phytoliths can be found in Table 2. There 

also appears to be considerable potential for discrimination of 

the conventional short-cell phytolith types using microdifferentiation of shape characteristics and phytolith size. 

EXAMPLES OF PHYTOLITH DISCRIMINATION AT AND 

BELOW THE SUBFAMILY LEVEL 

‘‘Long, wavy trapezoids” (Brown, 1984) appear to be unique 

to the Pooideae and can be used to identify this group of mainly 

high-elevation tropical grasses (Figure 23). Square to rectangular short-cell phytoliths of the kind described by Twiss et al. 

(1969) also may be diagnostic of tropical Pooideae, as they 

were not observed in taxa from other subfamilies analyzed 

herein. Phytoliths called “plateaued saddles” were isolated in 

great number from the leaves of Phragmites (Figures 24, 25). 

More study is needed before they can be assigned genusspecific status, but they can be used as a marker of the 

Arundinoideae and to search for, or rule out, the possible 

presence of Phragmites in soil phytolith assemblages. 

The Bambusoideae contribute a large number of types 

diagnostic at the family level (Table 2). Many of these are 

variations on saddle or bilobate themes. Typically, the 

phytolith, as found in tissue, is a thick structure with only one 

bilobate- or saddle-like face. When isolated from tissue, 

phytoliths turn from their original orientations to assume 

various kinds of shapes with acute points, “collapsed” sides, 

and other irregularities of structure (e.g., collapsed saddle, 

3 

one-and two-spiked-side body, saddle with ridged platform, 

Chusqoid body, bilobateisaddle both sides; Figures 26-3 1). 

Phytoliths just described are commonly found in the bamboo 

subtribes Guaduinae and Chusquineae and occur rarely in other 

bamboo taxa, not being noted at all in the tribe Olyreae (Table 

1). 

The Bambusoideae also contribute a large number of 

phytoliths diagnostic at the tribal, subtribal, and genus levels. 

Bodies whose long axes have two points and two large, 

rounded lobes are diagnostic of Chusquea, and they have been 

observed thus far only in two species of the genus, C. 

simplicijlora and C. pittieri (Figure 32). Chusquea bodies with 

multifaceted faces were observed only in C. pittieri, a highland 

representative of the genus (Figure 33). This distribution 

probably allows differentiation of the single lowland species of 

the genus currently recognized, C. simplicijlora. Large, 

distinctive bodies are produced in Streptochaeta spp. (Figure 

34), whereas Neurolepis contributes a diagnostic small and 

wide tent-shaped body (Figure 35). Pharus contributes a 

unique, wide body (Figure 36), whose smaller, lateral face 

presents as a biloboid structure in tissue. Raddiela spp. 

contribute bilobates and cross shapes that appear to be enclosed 

in siliceous plates (Figures 37, 38). 

The Olyreae produce a number of different kinds of 

genus-specific forms that are irregular versions of complex 

bilobates or crosses. Their orientation in plant tissue reveals 

these basic, short-cell shapes (Figure 39). When isolated from 

tissue, they are oriented differently and assume a number of 

diagnostic forms. For example, those in Maclurolyra and 

Pariana have one sinuous shape (representing the turned 

bilobate) and one sloping edge, and they are extremely wide. 

(Figures 40,41). Phytoliths from each of these genera appear to 

be differentiable on the basis of the regularity of the edge slope 

and the width of the body. Arberella contributes bodies with 

various irregular points and concavities on one edge (Figures 

Other phytoliths found in the Bambusoideae are diagnostic 

at the tribal level, Phytoliths previously described as irregular 

mesophyll (Piperno, 1988), but which are now also known to 

be irregular, complex short-cell phytoliths, are found in the 

Olyreae (Figures 45, 46). Cross-shaped bodies with partly or 

fully developed conical projections on one side, the “Variant 3 

and 8” types (Piperno, 1988), also are diagnostic of the Olyreae 

(Figure 17). Many bilobates from this tribe also display the 

same Variant 3 and 8 attributes (Figures 47, 48). Cross-shaped 

bodies with three indentations, blocky structures, and concave 

faces, and with blocky structures, concave faces, and serrated 

short axes are characteristic of Otateafimbriata and Chusquea, 

respectively (Figures 49, 50). 

The documentation of many diagnostic phytoliths in 

bamboos is of considerable significance because the subfamily 

often exhibits habitat preferences that are very different from 

other tropical grasses. Bamboos are commonly found in the 

shady, cool understorey of tropical forests rather than in open 

42-44). 
4 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

and disturbed vegetation. Bamboo phytoliths, then, can be 

important markers of various kinds of tropical forests in 

archaeological and paleoecological studies (see Piperno, 1988). 

The distribution of bamboo phytoliths by tribe and subtribe 

mirrors current taxonomic assessments of the family based on 

other anatomical and structural features (Soderstrom and Ellis, 

1987), indicating the fbndamental relationship of silica-body 

shape to Bambusoideae systematics. 

Smaller numbers of one-to-one associations between a 

phytolith and a tribe or genus were observed in other 

subfamilies. They occurred in Arundinella (Panicoideae), 

Aristida (Arundinoideae), Polypogon elongatus (Pooideae), 

and Aegopogon and Jouvea (Panicoideae) (Figures 5 1-56). 

Phytoliths from Aristida are called “rondeloidhaddleloid” 

because they display characteristics intermediate between 

classic rondels and saddles. Arundinella possesses an unusual 

phytolith that is tall, thick, and more-or-less saddle shape when 

found in tissue, and then assumes a diagnostic form when 

removed from the leaf (Figures 51, 52). It is very similar to 

phytoliths found in the Arundinoideae taxon Gynerium (Figure 

57) and to “saddlehilobate, both sides” types of phytoliths that 

are common in bamboos (Figure 3 1). 

Stebbins (1987) believed that the panicoid grasses derived 

via Arundinella from the Arundinoideae. The divergent set of 

phytoliths in Arundinella as compared to other species 

examined in the Panicoideae, as well as the similarity of the 

Arundinella leaf phytolith assemblage to that from some 

Arundinoideae taxa (predominance of wide, angled bodies and 

odd saddle shapes; few bilobates and crosses and no complex 

bilobates) are consistent with this proposed phylogeny. 

As noted above, there also is considerable potential for 

short-cell phytolith discrimination using microshaped features 

of the conventionally defined short-cell phytolith types. For 

example, bilobates with rounded or semirounded lobes and 

long, thin shafts, or with squared lobes and distinct, thin shafts 

are common in panicoid taxa, but they were not observed in 

bamboos (Figures 5, 7). Bamboo bilobates, in contrast, usually 

are squat bodies with no or unremarkable shafts (Figures 

11-13, 58, 59). Bilobates from the Chloridoideae (Figure 14) 

exhibit distinctively flared, convex edges that were first 

reported by Mulholland (1989). 

Size differences in bilobates from different subfamilies also 

are apparent. Many bilobates isolated from panicoid grasses 

exceed 20 microns in length, whereas those from the 

Bambusoideae, Cloridoideae, and Pooideae (with the exception 

of Stipa) are almost without exception shorter. 

Significant differences also are apparent from subfamily to 

subfamily in the type of saddle-shaped phytolith produced. 

Many phytolith assemblages from chloridoid grasses have 

significant proportions (32%-86%) of squat saddles, that is, 

the axis of the phytolith exhibiting the double-edge, saddle-like 

outline is wider than the other, or the two axes are 

equidimensional (Figures 18-20). In contrast, every species 

studied from the Bambusoideae and Arundinoideae produced 

assemblages in which over 90% of saddles were longer than 

wide (Figures 21, 22, 60). Another difference between saddles 

from chloridoid and non-cloridoid grasses is that very tall 

saddles, those measuring longer than 15 microns, dominate 

bamboo assemblages, whereas saddles shorter than 15 microns 

long predominate in chloridoids (Figure 22). 

PHYTOLITHS WITH LIMITED DISTRIBUTIONS IN THE POACEAE 

Phytoliths called “narrow elliptates” were isolated in great 

number from the Bambusoideae, especially the Guaduinae and 

Chusqueinae, where they are a major component of the 

intercostal areas of the leaf epidermis (Figures 61, 62). They 

were not observed in the Olyreae, Streptochaeteae, Phareae, 

Streptogyneae, or Neurolepidinae. Narrow elliptates also occur 

in small numbers in the Arundinoideae, having been observed 

thus far only in Gynerium (Figure 63). These phytoliths have 

biloboid characteristics when viewed in tissue (Figures 6 1, 63), 

but they may assume other shapes when removed from the leaf 

(Figure 62). 

Complex bilobates or trilobates and polylobates are common 

in phytolith assemblages from panicoid taxa. They were not 

observed, however, in the Bambusoideae and were extremely 

rare in the Arundinoideae, occurring in very small numbers 

(less than 1% of the short-cell assemblage) in a few culms. 

Complex bilobates also were observed in Eragrostis (Chloridoideae) and in Stipa (Pooideae). 

OTHER KINDS OF SILICA BODIES AND PATTERNS 

OF SILICIFICATION 

There are some types of phytoliths found in tropical grasses 

that do not lend themselves to easy description and classification. Many of them derive from culms, in which are typically 

found small, irregular phytoliths, especially in members of the 

Arundinoideae (Figures 64, 65). Other unusual phytoliths are 

insignificant components of assemblages from leaves and floral 

bracts (Figure 66). As no overlap occurs between these types of 

phytoliths and those from other families, they can be identified 

in soils or fossils as grass bodies. These phytoliths would repay 

further investigation, as some of them are likely to be of precise 

taxonomic value. 

Patterns of silicification in certain members of the bamboo 

subtribe Arthyrostilidiinae are most interesting, as it appears 

that leaf silica bodies characteristic of bamboos or other grasses 

are seldom produced. Most genera are characterized instead by 

the presence of small, silicified cone-like structures that arise 

from the epidermis (Figures 67-69). The comment that “this 

subtribe is rather far removed from the Arundinariinae and 

Bambusinae and appears to have arisen from a single ancestor 

different from that which gave rise to other New World woody 

subtribes such as the Chusqueinae, Guaduinae, and Neurolepidinae” (Soderstrom and Ellis, 1987:234) is amply supported 

by its silicification patterns. 
NUMBER 85 5 

OTHER IMPORTANT PHYTOLITHS NOT DERIVED FROM 

SHORT CELLS 

It is worthwhile to briefly review some other distinctive 

phytoliths that are formed in nonvegetative organs of the plant. 

Recent studies have shown that the silicification of epidermal 

tissue, proper, can result in distinctive phytolith shapes 

(Piperno and Pearsall, 1993). For example, the fruitcases of 

teosinte and Tripsacum produce genus- and, in the case of Zea 

luxurians (Guatemalan teosinte), species-specific forms (Figures 70, 7 1). Controversy surrounding the origin and evolution 

of these near relatives of maize, especially as they relate to 

maize evolution itself, has been long-standing and fervent. The 

distinctive fruitcase phytoliths may help to arrive at some 

resolution of the major conflicts. 

Summary 

GRASS TAXON IDENTIFICATION AND ENVIRONMENTAL 

RECONSTRUCTION FROM PHYTOLITHS RETRIEVED 

FROM ANCIENTROPICAL SOILS AND SEDIMENTS 

The information presented here demonstrates the importance 

of describing phytoliths after they are removed from plant 

tissue. Epidermal anatomy of many of the bamboo and other 

grass genera included in this research had been studied 

previously (Metcalfe 1960; Soderstrom et al., 1987; Soderstrom and Ellis 1987; Judziewicz and Soderstrom, 1989), but 

diagnostic phytoliths were missed because important shape 

attributes were hidden by plant tissue and, therefore, were 

difficult to ascertain. For example, Soderstrom et al. (1987) 

were able to note only that Pharus silica bodies (Figure 36) 

were horizontally elongated (having long axes aligned parallel 

to the long axis of the leaf) and bilobate-shape. Soderstrom and 

Ellis (1 987) described the unique phytoliths from Chusquea 

simply as bilobate-shaped bodies (compare Figures 32 and 72) 

and suggested that the same bodies occured in Pharus (Figure 

36). They were able to characterize the diagnostic Streptochaeta bodies only as a type of saddle shape and considered that 

they were very similar to those of Maclurolyra (compare 

Figures 34 and 40). Similarly, Metcalfe’s (1960) monumental 

study of Poaceae anatomy using epidermal thin sections could 

not reveal the range of phytolith shapes described here for the 

same reasons. 

This study has revealed a diverse and diagnostic set of 

phytoliths produced by bamboos, which should make bamboo 

presence quickly apparent in sediments. In many cases, 

tribal-and genus-specific identification will be possible. It 

already is clear that bamboo phytoliths attain a high representation in ancient sedimentary environments, as they have been 

identified with regularity in Late Pleistocene and Early 

Holocene-aged sites from Panama (Piperno, 1988; Piperno et 

al., 1991). 

With regard to the identification of other subfamilies, 

one-to-one correspondences between individual phytoliths and 

subfamilies are found with wavy trapezoids (Pooideae) (Figure 

23) and plateaued saddles (Arundinoideae) (Figures 24, 25). 

Other distinctive types limited in distribution to individual 

grass genera are described on page 4 and in Table 2. 

In addition, some specific rules can be derived from this 

study and applied in soil and sediment analysis to identify grass 

subfamilies. For example, a soil phytolith assemblage with 

significant proportions (greater than 30%) of squat saddles (see 

page 4) can be said to contain representation from chloridoid 

grasses with a high degree of confidence. Squat saddles 

consistently shorter than 15 microns also can be said to 

probably derive from the Chloridoideae. 

If the great majority (greater than 80%) of saddles are “tall,” 

bamboo (probably Guaduinae or Chusquinae) or Arundinoideae (Aristida or Phragmites) representation is implicated. If 

the arundinoid taxon Phragmites is present, the assemblage 

also should contain significant proportions of “plateaued 

saddles.” If an assemblage of tall saddles contains bamboo 

representation, it also should include one or more of the other 

types of phytoliths produced by bamboos (e.g., narrow 

elliptates, collapsed saddles, saddles with ridged platforms, 

etc.). Some primitive (see below) panicoids, such as Zsachne, 

also have assemblages dominated by tall saddles (Figure 73), 

but they lack the other, irregular forms. A phytolith assemblage 

of very tall (longer than 15 microns) saddles also suggests 

bamboo presence. 

Furthermore, a phytolith assemblage that contains bilobates 

with (1) semirounded or rounded lobes and long, thin shafts 

(Figures 5, S), (2) squared lobes and distinct, thin or moderately 

thin shafts (Figure 7), or (3) lengths consistently (with a 

proportion of greater than 20% of all bilobates) longer than 20 

microns probably contains representation from the Panicoideae, Arundinoideae (Aristida), or a genus in the Pooideae, 

Stipa. Presence of complex bilobates in this same assemblage 

indicates contribution by the Panicoideae andor Stipa (actually, such a combination is precluded by the ecological habitats 

of these grasses, see below). 

Attention to the above criteria, which can eliminate bilobate 

contribution by the Bambusoideae (Figures 10-13, 47, 48), is 

important in habitat reconstruction because the Panicoideae 

and Aristida typically occupy open and disturbed environments, not the shaded, forest environments preferred by the 

Bambusoideae. Habitat specificity of certain conkser taxa also 

can play a role in phytolith identification. For example, the 

Pooideae taxa that produce bilobates are high-elevation 

grasses; therefore, they probably can be ruled out as potential 

confusers in Holocene sediments from low- and mid-elevation 

tropical sites. 

This study also suggests that tropical soil assemblages might 

contain a significant proportion of silica bodies that are 

unclassifiable below the family level. In addition to certain 

types of bilobates, cross-shapes, and rondels that occur in all of 

the subfamilies of the Poaceae, there are other short-cell 

phytolith shapes that presently can be taken only as general 

indicators of grass presence. 
6 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

THE PLACE OF PHYTOLITHS IN PALEOAGROSTOLOGY AND 

GRASS SYSTEMATICS 

To reiterate points discussed above, the correlation of 

circular to oval, saddle, bilobate, or cross-shaped phytoliths 

observed in fossil grass specimens with specific subfamiles or 

tribes should be made cautiously, as significant deviations from 

the expected pattern may occur, and phytoliths still embedded 

in plant tissue may display subfamily links more apparent than 

real. Nevertheless, phytoliths should play a more prominent 

role in paleoagrostology than has, heretofore, been the case, as 

silica-body shape in tropical grasses exhibits more diversity 

than that in grasses of other regions. Subfamily links based on 

microdifferentiation of silica bodies (tall vs. squat saddles; 

bilobates with and without shanks) are apparent, and overall 

patterns of leaf epidermal silicification may be diagnostic at 

several taxonomic levels. Examples include the Bambusoideae 

(many kinds of diagnostic patterns, including tall and very tall 

saddles and narrow elliptates), Arundinoideae, particularly 

Phragmites (combination of tall saddles and plateaued saddles 

in costal areas), Pooideae (dominance of circular to oval 

phytoliths in costal areas; presence of wavy trapezoids), and 

Chloridoideae (many squat saddles in the costal area). 

Making precise identifications of fossil specimens from 

silica-body type will entail studying phytoliths in their natural 

orientations in leaves, where they tend to assume less 

distinctive shapes. At times, an identification should be 

possible, as the same phytolith, both when embedded in, and 

liberated from tissue, may assume idiosyncratic shapes that can 

be linked to each other (compare Figures 32 and 72, showing 

the Chusguea body as it is found in and out of leaf tissue). 

Some cases of identification may prove more problematic, 

however, with the Bambusoideae also coming to mind in this 

regard. For example, the manifold shapes assummed by the 

irregular, multilobed short cells of genera in the bamboo tribe 

Olyreae (Figures 40-46) are not immediately apparent when 

they are still enclosed within tissue, Similarly, all of the 

distinctive Arundinella bodies (Figures 5 1, 52) appear as 

simple, tall, saddle-like shapes when viewed in tissue. The 

most preferable scenario for positive identification of fossil 

grasses may be one in which part of the specimen in question 

can be sacrificed in order to remove the phytoliths. Clearly, 

paleoagrostological studies would benefit from a systematic 

comparison of phytolith appearance in and out of leaves. 

Patterns of silicification in structures other than leaves also 

may be diagnostic of certain taxa. For example, the inflorescence bracts of Aristida contain high numbers of rondeloidsl 

saddeloids, and those of the Olyreae also produce irregular, 

multilobed short-cell phytoliths. 

Also revealed by this study to be highly instructive in 

considerations of Poaceae taxonomy and phylogeny is phytolith shape in modem taxa. A review of Table 1 indicates that 

almost every taxon producing high amounts of atypical leaf 

phytoliths (those that are more characteristic of other subfamilies) occupies a primitive or otherwise singular position in its 

respective family. Some examples follow. 

Isachne, a panicoid grass, but a producer of tall saddles 

similar to those in Phragmites (compare Figures 60 and 73), 

and phytoliths with both saddle and bilobate characteristics 

(Table l), is thought to be a precursor of the Paniceae (Zuloaga, 

1987) and may be basal in the Panicoideae (Kellogg and 

Campbell, 1987). Eragrostis, a C3 grass (a photosynthetic 

pathway highly unusual in the Chloridoideae), is a contributor 

of numerous bilobates as well as saddles (Table 1) and may be 

basal in the Chloridoideae (Kellogg and Campbell, 1987). 

Stipa, a pooid producer of bilobates, may be basal in the 

Pooideae (Kellogg and Campbell, 1987). Some analysts 

(Macfarlane, 1987) question whether the genus belongs in the 

subfamily Pooideae; Barkworth and Everett (1987) place it 

instead in the Arundinoideae. Anomalous characteristics of the 

pooid Brachypodium have long been recognized, and the genus 

has been accorded separate tribal status in the Pooideae 

(Macfarlane, 1987). The interesting Arundinoideae-like phytolith assemblages produced by the primitive panicoid taxon 

Arundinella have been noted above (page 4). 

With the exception of Brachypodium, phytolith assemblages 

from all of the grasses just discussed are, on the whole, more 

similar to the Arundinoideae, from whose past members they 

are probably directly derived, than they are to other genera in 

their own subfamilies. It is clear that silica-body shape closely 

reflects phylogenetic relationships, and that phytolith shape 

changed along with other anatomical and micromorphological 

leaf characters in response to diversification and selective 

pressures during grass evolution. 

The major directional trends taken by silica-body shape as 

grass evolution proceeded can be discerned from phytoliths in 

the modem flora. The predilection of more primitive taxa 

(Arundinoideae, Bambusoideae, Isachne) to have tall saddles 

has been discussed. These grasses also are marked by a high 

proportion of phytoliths that have just one complete saddle- or 

bilobate-like face, are thick (as oriented in leaf tissue), and that 

consequently turn when removed from tissue to assume various 

irregular, angular shapes (Figures 26,28, 3 1,42, 5 1,52, 57, 74, 

75). Primitive taxa contribute phytoliths that combine the 

characteristics of saddles, bilobates, and rondels, or small, 

irregular bodies that defy a conventional classification (Figures 

53, 54, 64, 76). 

It can be deduced that the earliest grass phytoliths were often 

thick pieces of silica with only one saddle- or bilobate-type 

face. Leaf epidermes may have contained a general assortment 

of saddle-, bilobate-, and rondel-like siliceous bodies, with 

forms assuming traits intermediate between these major classes 

also being common. Most regular saddles were tall. Leaf 

epidermal silicifications that result in a dominance of planar, 

mirror-image saddles and bilobates characteristic of mainstream genera in the Chloridoideae and Panicoideae appear to 

be later developments. It also can be argued that chloridoid 

ancestors had leaf epidermes with bilobate silica bodies and 
NUMBER 85 7 

that panicoid ancestors had leaf epidennes with saddle-shaped 

silica bodies. 

In conclusion, this study has not described all of the 

short-cell phytoliths occurring in the tropical American flora. 

More studies are needed that include additional species in the 

larger genera of the Poaceae and also new taxa, as they continue 

to be described from the rain forest habitat. It also would be 

interesting to achieve a systematic study of the Old World 

tropical Poaceae in order to provide a key to geological/ 

archaeological phytolith identification and to explore ancient 

grass biogeographical relationships. Because extensive studies 

of African leaf epidermes with silica-body descriptions already 

have been carried out (e.g., Palmer and Gerbeth-Jones, 1986, 

1988 and references therein), a complementary analysis of 

disarticulated phytoliths is likely to enhance grass fossil 

identification in that part of the world. 
Literature Cited 

Barkworth, M.E., and J. Everett 

1987. Evolution in the Stipeae: Identification and Relationships of Its 

Monophyletic Taxa. In T.R. Soderstrom, K.W. Hilu, C.S. Campbell, 

and M.E. Barkworth, editors, Grass Systematics and Evolution, 

pages 25 1-264. Washington, D.C.: Smithsonian Institution Press. 

1971. Opaline Silica in the Range Grasses of Southern Alberta. Canadian 

Journal of Botany, 49:769-78 1. 

Brown, D. 

1984. Prospects and Limits of a Phytolith Key for Grasses in the Central 

United States. Journal ofArchaeologica1 Science, 1 1:22 1-243. 

Conert, H.J. 

1987. Current Concepts in the Systematics of the Arundinoideae. In T.R. 

Soderstrom, K.W. Hilu, C.S. Campbell, and M.E. Barkworth, 

editors, Grass Systematics and Evolution, pages 239-250. Washington, D.C.: Smithsonian Institution Press. 

A 620,000 Year Opal Phytolith Record from Central Nebraskan 

Loess. In I. Rovner, editor, Plant Opal Phytolith Analysis in 

Archaeology and Paleoecology. Occasional Papers of the 

Phytolitharien, 1 : 12-23. Raleigh, North Carolina: North Carolina 

State University. 

Blackman, E. 

Fredlund, G. 

1986. 

Grob, A. 

1896. Beitrage Sur Anatomie der Epidermis der Gramineenblatter. 

Bibliotheca Botanica, 36: unpaginated. 

Morphological, Anatomical, and Taxonomic Studies in Anomochloa 

and Streptochaeta (Poaceae: Bambusoideae). Smithsonian Contributions to Botany, 68: 52 pages. 

Phylogenetic Analysis of the Gramineae. In T.R. Soderstrom, K.W. 

Hilu, C.S. Campbell, and M.E. Barkworth, editors, Grass Systematics and Evolution, pages 3 10-324. Washington, D.C.: Smithsonian 

Institution Press. 

Man and Climate in the Mayan Lowlands. Quaternary Research, 

28:407-414. 

Late Pleistocene Climate in the Central American Lowlands. In P.K. 

Swart, K.C. Lohmann, J. McKenzie, and S. Savin, editors, Climate 

Change in Continental Isotopic Records. Geophysical Monographs, 

78: 165-1 78. American Geophysical Union, Washington, D.C. 

Poaceae Subfamily Pooideae. In T.R. Soderstom, K.W. Hilu, C.S. 

Campbell, and M.E. Barkworth, editors, Grass Systematics and 

Evolution. pages 265-276. Washington, D.C.: Smithsonian Institution Press. 

Anatomy of the Monocotyledons. I: Gramineae. London: Oxford 

University Press. 

Phytolith Shape Frequencies in North Dakota Grasses: A Comparison to General Patterns. Journal of Archaeological Science, 

A Test of Phytolith Analysis at Big Hidatsa, North Carolina. In D.M. 

Pearsall and D.R. Piperno, editors, Current Research in Phytolith 

Analysis: Applications in Archaeology and Paleoecology, pages 

Judziewicz, E.J., and T.R. Soderstrom 

1989. 

Kellogg, E.A., and C.S. Campbell 

1987. 

Leyden, B.W. 

1987. 

Leyden, B.W., M. Brenner, D.A. Hodell, and J.H. Curtis 

1993. 

Macfarlane, 'ID. 

1987. 

Metcalfe, C.R. 

1960. 

Mulholland, S.C. 

1989. 

16x489-511. 

1993. 

I3 1-145. Philadelphia: Museum of Applied Science. Center for 

Archaeology, University of Pennsylvania. 

Phytolith Analysis as a Means of Plant Identification: Arundo dona 

and Phragmites communis. Annals ofBotany, 61:209-2 14. 

A Scanning Electron Microscope Survey of the Epidermis of East 

African Grasses, IV. Smirhsonian Contributions 10 Botany, 62: 120 

pages. 

A Scanning Electron Microscope Survey of East African Grasses, V. 

and West African Supplement. Smithsonian Contributions to 

Botany, 67: 157 pages. 

1964. Types of Opaline Silica Deposition in the Leaves of British Grasses. 

Annals of Botany, 28: 169-1 85. 

1966. Opaline Silica in the Inflorescences of Some British Grasses and 

Cereals. Annals ofBotany. 30525-538. 

Paleoethnobotany: A Handbook of Procedures. 470 pages. San 

Diego: Academic Press. 

Phytolith Analysis: An Archaeological and Geological Perspective. 

280 pages. San Diego: Academic Press. 

Piperno, D.R., M.B. Bush, and P.A. Colinvaux 

Paleoenvironments and Human Occupation in Late Glacial Panama. 

Quaternary Research. 33: 108-1 16. 

Paleoecological Perspectives on Human Adaptation in Central 

Panama, I: The Pleistocene; 11: The Holocene. Geoarchaeologv, 

Ollendorf, A.L., S.C. Mulholland, and G. Rapp. Jr. 

1988. 

Palmer, P.G., and S. Gerbeth-Jones 

1986. 

1988. 

Parry, D.W., and F. Smithson 

Pearsall, D.M. 

1989. 

Piperno, D.R. 

1988. 

1990. 

1991. 

6:2 10-250. 

Piperno, D.R., and D.M. Pearsall 

1993. Phytoliths from the Reproductive Structures of Teosinte: Implications for the Study of Maize Evolution. Journal ofArchaeologica1 

Science, 20:337-362. 

La Systematique des Graminees. Annales des Sciences IVaturelles, 

Botanique, series 2, 18: 165-258. 

The Position of Bamboo Genera and Allies in a System of Grass 

Classification. In T.R. Soderstrom, K.W. Hilu, C.S. Campbell, and 

M.E. Barkworth, editors, Grass Systematics and Evolution. pages 

225-238. Washington, D.C.: Smithsonian Institution Press. 

1987. The Phareae and Streptogyneae (Poaceae) of Sri Lanka: A 

Morphological-Anatomical Study. Smithsonian Contributions to 

Botany, 65: 27 pages. 

Grass Systematics and Evolution: Past, Present and Future. In T.R. 

Soderstrom, K.W. Hilu, C.S. Campbell, and M.E. Barkworth, 

editors, Grass Systematics and Evolution. pages 359-367. Washington, D.C.: Smithsonian Institution Press. 

Prat, H. 

1936. 

Soderstrom, T.R., and R.P. Ellis 

1987. 

Soderstrom, T.R., R.P. Ellis, and E.M. Judziewicz 

Stebbins. G.L. 

1987. 

Thomasson, J.R. 

1984. Miocene Grass (Gramineae: Arundinoideae) Leaves Showing 

External Micromorphological and Internal Anatomical Features. 

Botanical Gazette, 145:204-209. 

Fossil Grasses: 1820-1986 and Beyond. In T.R. Soderstrom, K.W. 

Hilu, C.S. Campbell, and M.E. Barkworth, editors, Grass Systema1987. 

8 
NUMBER 85 9 

tics and Evolution, pages 159-167. Washington, D.C.: Smithsonian 

Institution Press. 

A Fossil Grass (Gramineae-Chloridoideae) from the Miocene, with 

Krantz Anatomy. Science, 233:876-878. 

Morphological Classification of Grass Phytoliths. Soil Science 

Society of America Proceedings, 33: 109- 11 5. 

Thomasson, J.R., M.E. Nelson, and R.J. Zakrzewski 

1986. 

Twiss, P.C., E. Suess, and R.M. Smith 

1969. 

Watson, L., H.T. Clifford, and M.J. Dallwitz 

1985. The Classification of Poaceae: Subfamilies and Supertribes. Austrulian Journal of Botany, 33:433-484. 

Systematics of New World Species of Punicum (Poaceae: Paniceae). 

In T.R. Soderstrom, K.W. Hilu, C.S. Campbell, and M.E. Barkworth, editors, Grass Systematics and Evolution, pages, 287-306. 

Washington, D.C.: Smithsonian Institution Press. 

Zuloaga, F.O. 

1987. 
Taxon 

PANlCOlDEAE 

Acrocereus rizianoides (H.B.K.) Dandy 

Aegopogon cenchroides H. & B. ex Willd. 

Aegopogon tenellus (DC.) Trin 

seed 

leaf 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

leaf 

inflorescence 

leaf 

Andropogon bicornis I.. 

Andropogon brevfolius Swartz 

Andropogon leucostachyus Kunth 

Andropogon liebmanni Hack. 

Andropogon scoparius Michaux 

Andropogon virginicus L. 

Anthephoru hermaphrodita (L.) Knntze 

Arundinella berleroniana (Schult.) Hitchc. I 

Chase 

leaf 

inflorescence 

leaf 

culm 

inflorescence 

leaf 

culm 

inflorescence 

Arundinella deppeana Nees in Steud. 

Arundinella hispidu (H. & R.) Kuntze 

TABLE 1 .-Distribution of phytolith types observed in the grasses studied. Within the Panicoideae, Chloridoideae, 

Arundinoideae, and Pooideae, x =characteristic of the taxon's subfamily; * =considered to be characteristic of other 

subfamilies, present in small numbers, i.e., <lo% of the silica-body assemblage; o =considered to be characteristic 

of other subfamilies, present in substantial quantities, i.e., usually >20% of the silica-body assemblage. For all taxa, 

P in the "Other" category indicates the presence of other kinds of short-cell phytoliths in the assemblage; the letter 

P followed by the first letter of the genus in parentheses, e.g., P(T) for Trip.sacum, indicates these phytoliths have not 

been observed in other taxa. 

xx 

xx 

xx 

xx 

xx 

no phytoliths observed 

xx 

xx 

xx 

X 

xx 

xx 

xx 

xx 

* 

X 

xx* 

o 

x x 0 

no phytoliths observed 

to 

X 00 

* X * 0 
TABLE 1 .--Continued. 

Taxon 

Axonopus uureus Heauv. 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

leaf 

Axonopus compressus (Sw.) Heauv. 

Axonopus purpusii (Mez) Chase 

Cenchrus brownii R. & S. 

Cenchrus echinutus L. 

Cenchrus pilosus H.B.K. 

Chaetium bromoides (Presl) Bcnth. ex Iiemsl. 

Coelorhachis auriru (Steud.) A. camus 

Clenium concissum Swallen 

Echinochloo crmpuvonis (H.B.K.) Schult. 

Echinochloa haleiformis (H.B.K.) Chase 

Echinoluenu grucilis Swallen 

tkickelochlou grunu1uri.y (L.) Kuntze 

Herer-opogon contortus (L.) Beauv. 

Ikleropogon melanocurpus (Ell.) Benth 

Honrolepis ururensis (H.B.K.) Chase 

tbmenuche amplexicuulis (Rudge) Nees 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X * 7. 0 

X 

X 

X 

X 

X 

X 

0 

0 

* 

0 

X 

X 

X 

X 

X 

X 

** 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

T 

X 

* 

* 

* 

0 

* 
12 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

P, 

0 

X X xx XX xx xx x x x xx x X 

xx x x x x x xx xx xx x x x x xx x x xxx 
x x x xxx xx xxxx xxx xx xxx xxx x xxx * 

x xxx xx xxxx xxx xx xxx xxx x xxx * 

xx X 

* 0 * 0 * * * * 

El 
TABLE I.--Continued. 

Taxon 

Eleusine indica (L.) Gaertn. 

Eragrostis ciliaris (L.) R. Br. in Tuckey 

Eragrostis mexicana (Hornern.) Link 

Leptochloa dominguensis (Jacq.) Trinius 

Leptochloa scabra Nees 

leaf 

leaf 

leaf 

leaf 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

culrn 

leaf 

Muhlenbergia distans Swallen 

Muhlenbergia emersleyi Vasey 

Muhlenbergia implicata (Kunth) Kunth 

Muhlenbergia lehmanniana Henr. 

Sporobolus cryptandrus (Torrey) A. Gray 

ARUNDINOIDEAE 

Aristida capillacea Lam. 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

culrn 

inflorescence 

leaf 

inflorescence 

Aristida divaricata H. & B. ex Willd. 

Aristida jorullensis Kunth 

Aristida orizabensis Fourn. 

Aristida orizaliensis 

Aristida oriza1iensi.s 

* 

0 

0 

0 

0 

* 

* 

* 

* 

0 

0 

0 

0 

* 

0 

0 

0 

0 

0 

0 

0 

X 

X 

X 

X 

X 

X 

*x 

*X 

*x 

* 

* 

* 

* 

t 

* 

* 

0 

* 

* 

0 

* 

* 

0 

0 

* 

* 

* 

* 
Taxon 

Aristida recurvuta H.B.K. 

leaf 

culm 

inflorescence 

leaf 

culm 

inflorescence 

leaf 

culm 

inflorescence 

Orthoclada Iaxa (L. Rich.) Beauv. 

leaf 

Phragmites australis (Cav.) Trin. ex Steud. 

leaf 

POOIDEAE 

Agrostis tolocensis Kunth 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

leaf, culm, sheath 

inflorescence 

leaf and sheath 

inflorescence 

leaf and sheath 

inflorescence 

leaf 

culm 

inflorescence 

leaf 

culm 

inflorescence 

leaf 

culm 

inflorescence 

Aristida ternipes Cav. 

Gynerium sagittatum (Aubl.) Beauv. 

Brachypodium mexicanum (R. & S.) Link 

Bromus sp. 

Bromus brevis Nees ex Steud. 

Bromus carinatus Hooker & Arnott 

Bromus exultatus Bernh. 

Calamagrostis eminens (Presl.) Steud. 

Calamagrostis humholtiana Steud. 

Calamagrostis macrophylla (Pilger) Pilger 

0 

* 

0 

0 

0 

0 

* 

* 

o 

0 

o 

* 

* 

o 

o 

0 

X 

X 

* X 

X 

X 

X 

X 

X 

X 

X 

X 

no phytoliths observed 

X 

no phytoliths observed 

X 

X 

no phytoliths observed 

X 
TABLE 1 ;--Continued. 

Taxon 

Cinna poaeformis (Kunth) Scribn. & Men. 

leaf 

inflorescence 

leaf 

leaf 

culm 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

culm 

inflorescence 

leaf 

culm 

inflorescence 

leaf 

culm 

inflorescence 

leaf 

culm 

inflorescence 

BAMBUSOIDEAE 

OLYREAE 

Arberella dressleri Soders. & Calderon 

leaf 

Arberella longifolia Soders. & Zuloaga 

leaf 

Cryptochloa dressleri Soders. 

leaf 

inflorescence 

leaf 

Diectomis fmtigiata (Sw.) H.B.K. 

tIolcus Ianatus L. 

Lnlium multijlorum Lam. 

Polypogon elongatus H.B.K. 

Polypogon elongatus H.B.K. 

Polypogon elongatus H.B.K. 

Stipa ichu (Ruiz & Pavon) Kunth 

Stipa mucronata H.B.K. 

Trisetum deyeurioides (Kunth) Kunth 

Trisetum tonduzii Hitchc. 

Lithachne pauciyora (Sw.) Beauv. ex Poir 

xx 

X 

xx 

X 

xx 

X 

0.12 X 

X 

OJ2 X 

X 

412 X 

X 

X 

X 

no phytoliths observed 

0 X 

0 X 

* 

X 

no phytoliths observed 

X 

xx 

X 

xx 

x x3.8 

x x3S 

xx 

x x15 

x x3 

xx 

xx 

X 

X 

X 
TARLE I .<ontinued 

Taxon 

Maclurolyra tecta Calderon & Soders. 

leaf 

inflorescence 

Olyra cordfalia H.B.K. 

leaf 

Olyra latfolia L. 

leaf 

inflorescence 

leaf 

inflorescence 

leaf 

inflorescence 

Olyra micrantha H.B.K. 

Pariana campestris Aubl. 

Raddiella esenbeckii (Steud.) Calderon & Soders. 

leaf 

leaf 

Raddiella nana (Doell) Swallen 

CHUSQUEINAE 

Chusquea grandijlora Clark 

leaf and sheath 

inflorescence 

leaf and culm 

inflorescence 

leaf 

leaf 

culm 

leaf 

leaf 

leaf 

inflorescence 

leaf and culm 

inflorescence 

Chusquea longiflia Swallen 

Chusquea patens Clark 

Chusquea pittieri Hack. 

Chusquea pohli Clark 

Chusquea simplicijlora Munro 

Chusquea iirgafa Hack. 

Chusquea iwlcanalis Sodcrs. & Calderon 

NEIJR0LEPII)I NAE 

Neurolepis pittieri McClure 

leaf 

inflorescence 

x XI1 

x x15 

X 

x XX X 

x xx 

XI3 

X 

X 

x x3,8 

xx 

X 

X X 

xx X 

X 

X 

x x3 

x x3 

xxx 

xxx 

X X 

xxx 

X X 

xxxx 

xxx X 

X 

xxx 

X 

X 

X 

X 

X xxx 

X xx 

X xxx 

xxx 

X xx 

xx X 

X 

X 

X 

X 

xx x 
TAULE 1 .---Continued. 

Taxon 

~ 

GUADUINEAE 

Criciuma asymmefricu Soders. & LondoAo 

Criciuma asymmetrica Soders. & Londoiio 

Guadua amplexfolia (Presl.) Schult. f. 

leaf 

leaf 

leaf sheath 

culm 

inflorescence 

leaf 

culm 

leaf sheath and culm 

leaf 

inflorescence 

leaf 

culm 

leaf 

inflorescence 

leaf 

culm 

leaf 

inflorescence 

leaf 

fruit 

leaf 

leaf 

inflorescence 

leaf 

culm 

Guadua amplexfolia (Presl.) Schult. f. 

Guadua amplexfolia (Presl.) Schult. f. 

Guadua angust(fo1ia Kunth 

Guadua anguslifolia Kunth 

Guadua lafifolia H. & R. 

Guadua latfolia H. & B. 

OImeca recta Soders. 

Olmecu recta Soders. 

Olmeca reflexa Soders. 

Otafeu acuminafa Calderon & Soders. 

Otafea fimbriata Calderon & Soders. 

STREPTOCHAETEAE 

Sfrepfochaefa sodiroana Hack. 

leaf 

inflorescence 

leaf 

Sfreptochaefa spicafa Schrad. ex Nees 

X X X X 

X X X 

X 

X 

X X 

X 

X 

X 

X 

X 

X 

xx 

X 

X X 

X 

X 

X 

xx 

X 

no phytoliths observed 

X X 

xxxx 

X X 

xxx 

X X 

no phytoliths observed 

X 

X 

X 

xx 

X 

X 

X 

xxx 

X 

xx 

xx 

X 

xx 

xx 

X 

xx 

xx 

X 

X 
NUMBER 85 19 

C 

X 

F 

P e c e 

x X X 

X 

X 

X xx xx 

X X 

xx x X xxx 

xx 

X x X x xx xx x x x xx XX 

xx 
SMITHSONIAN CONTRIBUTIONS TO BOTANY 

XXXX 

xxx X 
NUMBER 85 21 

TABLE 2.-The occurrence and distribution of phytoliths diagnostic at and below the subfamily level. 

Phytolith Taxa 

Long, wavy trapezoids (Figure 23). 

Plateaued saddles (Figures 24, 25). 

Collapsed saddles (Figures 26,27); two-spiked body 

(Figure 28); saddle with ridged platform (Figure 

29); Chusqoid body (Figure 30); saddlehilobate 

both sides (Figure 31). 

Chusquea body (Figures 32, 33). 

Pharus body (Figure 36). 

Enclosed in siliceous plates (Figures 37, 38) 

Irregular and extremely wide, with one sinuous and 

Irregular and wide, with one sinuous and one 

one sloping edge (Figure 40). 

sloping, pointed edge (Figures 42-44). 

Irregular, complex short-cell phytoliths (Figures 45, 

46). 

Cross-shaped and bilobate phytoliths, with one tier 

having conical protrusions, called the “Variant 3 

and 8” types (Figures 17,4748). 

Considerably wide; marked by the presence of one 

somewhat concave and one somewhat sloping 

edge (Figures 51, 52). 

“RondeloidBaddeloid” (Figure 53). 

Cross-shaped and bilobate, with one tier having a 

saddle-like structure that extends only about 

two-thirds of the length of the longer cross or 

bilobate side (Figure 55). 

Irregular bodies marked by one highly decorated 

lateral edge (Figure 56). 

Bodies with elliptoidhiloboid tendencies (Figures 

6 1-63). 

Pooideae, not observed in Calamagrostis or Stipa. 

Phragmites. 

Bambusoideae. Most common in the subtribes 

Guaduinae and Chusquineae. Not observed in the 

Olyreae. 

Chusquea. Absent from most members of the genus 

Pharus. An idiosyncratic type of phytolith, even for 

studied. 

bamboos. 

Raddiela. These phytoliths seem to have hyperdeveloped Olyreae characteristics. 

Maclurolyra. Morphology similar to those in Pariana, but bodies are much larger. 

Arberella. Differentiated from Mclurolyra and Pariana by one edge with irregular concavities and 

points. 

Olyreae. Of the same origin as phytoliths described 

from Arberella and Maclurolyra but more widespread in distribution. 

Olyreae. A three-dimensional structure of silica 

bodies that is highly useful in grass discrimination. 

Arundinella. 

Aristida. 

Polypogon. 

A egopogon 

Bambusoideae, especially intercostal areas of the 

Guaduinae and Chusqueinae, and Gynerium 

(Arundinoideae). 
22 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURES 1-4.--1, A rondel from Stipa ichu (~400). 2, A rondel from the culm of Guadua angustifoh (x400). 

3, Rondels from the cob of Zea mays L., race Maiz Ancho (x400). As the rondel phytoliths from maize, and 

especially bamboos (Figures 1, 3), tend to be thick when formed in the plant, the rondel faces that are orientated 

toward the investigator in plant tissue become the lateral edges of the phytoliths after they are removed from the 

plant and mounted on slides. 4, Center, three rondels from the inflorescence of Guadua larifolia. The phytolith at 

the top is a bilobate (x400). 
NUMBER 85 

FIGURES 54-5, Bilobates with semirounded lobes and long, thin shafts from Andropogon leucbostacbya 

(x200). 6, Bilobates and a complex bilobate from Panicum fasciculatum (x200). 7, Center, a bilobate with squared 

lobes and a distinct, moderately thin shaft from Andropogon bicornis (~200). 8, Bilobates with semirounded lobes 

and long, thin shafts from Aristidu orizaliensis (x200). 

23 
24 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURES 9-12.-9, Bilobates and complex bilobates from Stipa mucronuta (~200). 10, A row of bilobates from 

Chusqueapatens (x200). Their morphology, although not ovelapping the panicoid types, is unusual for bamboos. 

11, A bilobate from Maclurolyru recta (x200). 12, Bilobates in tissue from Chusquea pohli (x200). 
NUMBER 85 25 

FIGURES 13-16-13, Bilobates from the culm of Chusquea longifolia (x400). 14, A bilobate (left) and a 

cross-shaped phytolith (right) from Eragrostis mexicana (x200). The bilobate has four indentations and both 

phytoliths have the flared edges typical of the Chloridoideae. 15, Center, a complex bilobate from Eragrostis 

mexicana with multiple indentations (x200). 16, A Variant 1 (mirror-image) cross-shaped phytolith from Zea 

mays (x400). 
26 SMITHSONlAN CONTRIBUTIONS TO BOTANY 

FIGURES 17-20.-17, A Variant 3 cross-shaped phytolith from Arberella dressleri with conical protrusions on 

the upper face (x400). 18, Center, two squat saddles, and top, a tall saddle from Chloris eiliara (x400). 19, 

Saddle-shaped phytoliths from Muhlenbergii emersleyi. Many of them are squat saddles (x200). 20, 

Saddle-shaped phytoliths from Dactyluctenium aegpticum. Many of them are squat (x200). 
NUMBER 85 

FIGURES 21-24.-21, Saddle-shaped phytoliths from Guadua amplexz~olia. All but one are tall (~200). 22, 

Saddle-shaped and narrow-elliptical phytoliths from Guadua ampiexifoiia. All of the saddles are very tall (x200). 

23, Top, a long, wavy trapezoid from Triticum aestiwm (x400). 24, Center, a plateaued saddle from Phragmites 

australis (x400). 

27 
28 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURES 25-28.-25, A plateaued saddle from Phragmites australis (~400). 26, A collapsed saddle from 

Chusquea grandiflora (~400). 27, A partially collapsed saddle from Chusquea grandiyora (~400). 28, A 

two-spiked-side phytolith from Chusquea grandiflora. Spikes are present on the bottom of the phytolith (x400). 
NUMBER 85 29 

FIGURES 29-32.-29, Center, a saddle with a ridged platform from Chusquea grandiflora (x400). 30, A 

Chusqoid body from Criciuma asymmetrica. This phytolith, unlike the Chusquea body, is fairly widely 

distributed in bamboos (x400). 3 1, A saddlehilobate both sides type of phytolith from Chusquea grundi’j7ora 

(x400). 32, Right and left, Chusquea-body phytoliths diagnostic of this genus from Chusquea simplicifloru. The 

phytolith on the bottom left is still orientated as it would appear in the leaf (x200). The center phytolith is a 

bilobate. 
30 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURES 33-36.-33, A multifaceted Chusquea-body phytolith from Chusquea pittiera (x400). 34, SEM 

photograph of a Streptochaeta-body phytolith from Srreptochaera sodiroana, with lateral edges consisting of 

(left) a concave bilobate and (right) several saddle-like structures (~1000). 35, A small, wide, tent-shaped body 

from Neurolepis pittiera (x400). 36, A Pharus body characterized by its flatness, considerable width, and 

presence of (bottom left) dumbboid and (upper right) rectanguloid lateral edges (x400). 
NUMBER 85 31 

FIGURES 37-40.-37. A biloboid from Raddiela nana enclosed in a siliceous plate (x400). 38, A 

cross-shaped-like phytolith from Raddiela nana enclosed in a siliceous plate (x400). 39, An irregular, complex 

short-cell phytolith from Maclurolyra recta orientated as it would be in leaf tissue (x400). Compare with Figure 

40. 40, An irregular, complex short-cell phytolith from Maclurolyra fecra exhibiting extreme width and one 

sinuous and one sloping edge (x400). 
32 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURES 41-44.-41, A phytolith from Pariana campestris with one sinuous and one sloping edge. It is neither 

as tall nor as wide as that from Maclurolyra tecta (x400). 42, A phytolith From Arberella dressleri with one 

sinuous and one concave, irregularly pointed edge (x400). 43, A phytolith from Arberella dressleri with one 

sinuous and one concave, irregularly pointed edge (x400). 44, A phytolith from Arberella dressleri with one 

sinuous and one irregularly pointed edge (x400). 
NUMBER 85 33 

FIGURES 45-48.-45, Top and bottom, irregular, complex short-cell phytoliths from Ulyra latifolia. These 

phytoliths are characteristic of the tribe Olyreae. The phytolith in the center is a bilobate (x200). 46, An irregular, 

complex short-cell phytolith from Pariana campestris (x400). 47, A Variant 3 bilobate phytolith from Arberella 

dressleri. The phytolith is partially turned, revealing aspects of both of its faces (~400). 48, Center, two Variant 

8 bilobates from Ulyra latifolia (x400). 
34 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURES 49-52.-49, A thick, cross-shaped phytolith with a concave face from Otateafimbriata (x400). Most 

cross-shaped phytoliths from this species have only three indentations. 50, A cross-shaped phytolith from 

Chusquea pittieri with serrated short axes, three indentations, and a concave face (~400). This phytolith is not as 

thick as is usual in the genus. 5 1, A phytolith from ArundineZla confinis marked by considerable width and the 

presence of one slightly concave and one somewhat sloping edge (x400). 52, A phytolith from Arundinella 

confinis marked by considerable width and the presence of one somewhat concave and one somewhat sloping 

edge (x400). 
NUMBER 85 35 

FIGURES 53-56.-53, A rondeloidkaddeloid phytolith from the inflorescence of Aristida recurrafa. As the name 

implies, it exhibits features characteristic both of phytoliths in the Pooideae and Chloridoideae (x400). 54, Top, 

a rondeloidsaddleloid phytolith from Aristida orizaliensis. Also present is a bilobate (x400). 55, A unique type 

of cross-shaped phytolith, from Polypogon elongatus, in which one side of the phytolith has a saddle- or 

bilobate-like structure that extends only about two-thirds the length ofthe longer, cross-shaped side. It is also very 

wide. The phytolith is slightly turned, thus both faces may be seen (x400). Bilobates from this grass also carry the 

same features. 56, A phytolith from Aegopogon cenchroides (x400). 
36 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURES 57-60.-57, A phytolith typically produced in the leaves of Gynerium sagittarum (x400). 58, Center, 

a bilobate from the inflorescence of Guadua latijiolia (x400). 59, Center, bilobates from the inflorescence of 

Chusquea tongifolia. They are attached to two elongated phytoliths (x200). 60, A tall saddle from Phragmites 

australis (~400). 
NUMBER 85 

FIGURES 61-64.-61, Narrow elliptate phytoliths from Guadua latifolia still enclosed in tissue (x400). 62, 

Narrow elliptate phytoliths from Guadua angustifolia removed from tissue (x400). 63, A narrow elliptate 

phytolith from Gyneriurn sagittaturn (x400). 64, An odd silica body from the culm ofAristida ternipes (x400). 

37 
38 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURES 65-68.-65, An odd silica body with saddle tendencies from the culm of Aristida orizuliensis (x400). 

66, An unusual silica body from the inflorescence of Aristida orizuliensis (x400). 67, Top, conical siliceous 

bodies emerging from the leaf epidermis of Elytrostachys clanisera (x400). 68, Two-peaked conical siliceous 

bodies in epidermis from Elytrostachys clanisera (x200). 
NUMBER 85 39 

FIGURES 69-72.-69, A two-peaked conical siliceous body from Actinocladum merticulatum (x400). 70, A 

genus-specific epidermal-cell phytolith from the fruitcase of Tripsacum lanceolatum (x400). 7 1, A 

teosinte-specific epidermal-cell phytolith from the hitcase of Balsas teosinte (Zea mays ssp. pamiglumis var. 

pamiglumis) (x400). 72, Top, a Chusquea-body phytolith as it would appear in leaf tissue. Below is a 

Chusquea-type bilobate (~400). 
40 SMITHSONIAN CONTRIBUTIONS TO BOTANY 

FIGURES 73-76.-73, A tall saddle from Isachne arundinaceae (x400). 74, A typical phytolith from Gynerium 

saggitatum (x400). 75, Right, a thick, collapsed saddle from Guadua amplexifolia (x400). 76, A phytolith with 

both saddle and bilobate characteristics from Guadua amplexifolia (x400).