The morphology of Leptochloa fascicularis (Lam.) Gray (Poaceae) was studied in 25 locations in eastern and central Nebraska to determine if this grass was separable into two distinct taxa as suggested in several recent sources. Field collections were supplemented with herbarium specimens from other parts of the Central Great Plains. Glume and lemma lengths, the characters used in published keys, provided no separations useful in dividing the material into two species or varieties. However, individual local populations exhibited significant differences from each other in these characters. Such local differences appear to be reasonable given the high degree of inbreeding that appears to be prevalent at most locations

Templeton, Todd A.

English

The University of Nebraska, Omaha

University of Nebraska at OmahaDigitalCommons@UNOBiology Faculty Publications Department of Biology1991A Taxonomic Study of Variation in LeptochloaFascicularis (LAM.) Gray in the Central GreatPlainsTodd A. TempletonUniversity of Nebraska at OmahaFollow this and additional works at: https://digitalcommons.unomaha.edu/biofacpubPart of the Biology Commons, and the Plant Biology CommonsThis Article is brought to you for free and open access by the Departmentof Biology at DigitalCommons@UNO. It has been accepted for inclusionin Biology Faculty Publications by an authorized administrator ofDigitalCommons@UNO. For more information, please contactunodigitalcommons@unomaha.edu.Recommended CitationTempleton, Todd A., "A Taxonomic Study of Variation in Leptochloa Fascicularis (LAM.) Gray in the Central Great Plains" (1991).Biology Faculty Publications. 42.https://digitalcommons.unomaha.edu/biofacpub/421991. Transactions of the Nebraska Academy of Sciences, XVIII: 151-155 A TAXONOMIC STUDY OF VARIATION IN LEPTOCHLOA FASCICULARIS <LAM.) GRAY IN THE CENTRAL GREAT PLAINS Todd A. Templeton Oepartment of Biology University of Nebraska at Omaha Omaha, NE 68182-0040 The morphology of Leptochloa fascicularis (Lam.) Gray (Poaceae) was studied in 25 locations in eastern and central Nebraska to determine if this grass was separable into two distinct taxa as suggested in several recent sources. Field collections were supplemented with herbar-ium specimens from other parts of the Central Great Plains. Glume and lemma lengths, the characters used in published keys, provided no separations useful in di-viding the material into two species or varieties. How-ever, individual local populations exhibited significant differences from each other in these characters. Such lo-cal differences appear to be reasonable given the high de-gree of inbreeding that appears to be prevalent at most lo-cations. t t t INTRODUCTION Leptochloa fascicularis (Lam.) Gray is an an-nual grass found in muddy or wet soils in marshes, along ditches and as a weed in parking lots. Glea-son and Cronquist (1963) recognized this taxon as one species with three varieties, of which L. fascicu-laris var. fascicularis and L. fascicularis var. acuminata (Nash) Gleason are found in the Great Plains. Separation of varieties by Gleason and Cronquist was based on the length of the glumes and lowest lemma. McNeill (1979) (who placed these taxa in the genus Diplachne) considered L. acuminata (Nash) Mohlenbrock (as D . . acuminata Nash) a species distinct from· L. fascicularis (as D. fascicularis (Lam.) Beauv.) based on the length of the glumes and the lowest lemma and on the scabrosity of the panicle and blade. In McNeill's treatment, L. fas-cicularis was reported to have a first-glume length of 1.3-2.0 mm, second-glume length of 2.2-3.5 mm 151 and lowest lemma length of 2.0-4.0 mm. L. acuminata was said to have a first-glume length of 2.0-4.0 mm, second-glume length of 3.5-5.0 mm and lowest lemma length of 4.0-5.0 (8) mm and a more scabrous panicle and blade than L. fascicu-laris. Fernald (1950) and Dore and McNeill (1980) also recognized both L. fascicularis and L. acumi-nata (as Diplachne) as did Mohlenbrock (1973) (as Leptochloa). All of these authors made separations similar to those made by McNeill, although Fernald suggested a gap in measurements between the two species. Dore and McNeill cited one collection from a railroad yard near Niagara Falls as evidence of a separate species. Mohlenbrock (1973) recognized distinct species based on 12 collections of L. fascicu-laris and one collection of L. acuminata. MATERIALS AND METHODS Collections of the Leptochloa fascicularis com-plex were made in 22 locations in eastern and cen-tral Nebraska between July and September in a wide variety of habitats. Habitats collected from in-cluded roadsides, wet ditches and parking lots in sand, mud, gravel on crushed rock substrates. These collections were supplemented with 96 herbar-ium specimens borrowed from the University of Kansas (KANU). This material contained plants from a wide variety of habitats in New Mexico, Texas, Oklahoma, Kansas, Nebraska, South Dakota, North Dakota and Illinois. In the text which follows, the term "Great Plains collections" includes both the 22 field collections and the 96 herbarium specimens. In addition to this general sample, large population samples, termed 152 Leptrehloa "individual population collections" were collected in three locations in eastern Nebraska during July and August so that the extent of variability in single populations could be estimated. Morphology of the spikelet was observed and measurements were recorded for the length of the first and second glume, lowest lemma, lemma awn, pedicel, spikelet and ligule. All data were obtained from spikelets on the middle of the panicle. The Duncan Multiple Range Test, the Student-Newman-Keuls Test, and Schefl'e's Test (Allen, 1982) were used for characters measured on the three individ-ual population collections. A hybrid index (Bell, 1967) was also applied to these populations so that several characteristics could more easily be visual-ized at the same time. The separations used in the construction of this index were mainly those of Fer-nald (1950), since he left room for intermediate con-ditions. However, the separation used for first-glume length was that of McNeill (1979), since Fer-nald did not discuss that character. Blade width and scabrosity of the panicle and blade were also recorded on much of the material. All of these mea-surements were made using an ocular micrometer in a dissecting microscope. Field observations of the florets were made using a hand lens to deter-mine if the anthers were exserted at the time of col-lection. OBSERVATIONS AND RESULTS Collections made in early July showed that Lep-tochloa fascicularis commonly flowered within the sheath. Upon dissection of the individual florets, anthers were found to be tangled in the stigmas. Later in the flowering period the panicles were commonly exserted from the sheath, but the fre-quency of the anthers being exserted from the florets depended on the habitat. Plants collected in wet habitats commonly had some, but not all, anthers exserted on individual spikelets. Plants collected in dry habitats normally did not have any anthers exserted. Great Plains collections The characters analyzed, the lengths of the two glumes and the lemma, were those used by previous workers. Other characters measured either 1) showed very similar patterns of variation (e.g., pedicel length), or 2) varied erratically over a wide range (e.g., ligule length and scabrosity of panicle and blade), or 3) varied over such a narrow range that it was impossible to measure them precisely us-ing the available equipment (e.g., anther length). In the Great Plains collections, first-glume length ranged from 1.0-4.0 mm, second glume from 1.7-6.2 mm, and lowest lemma from 2.1-6.8 mm. Scatter diagrams involving these three char-acteristics (Figs. 1 and 2) show no obvious separa-tion into two populations. Using McNeill's or Fer-nald's separations, a number of individual plants would have been identified as one species using first-glume length and another species using sec-ond-glume length with similar consequences when comparing second-glume length and lemma length. Using Fernald's separations, a high per-centage of the plants of this collection were interme-diate between the two taxa. E .s ~ is> c: Q) ..J Q) E .il C!) "0 c: 0 () Q) en E .s ~ is> c: Q) ..J ~ E Q) ..J c 7 6 5 4 3 ! " "" """ J .. ..... ... i .. aa ••• ::--===-~~~=-=: "":II·"~ • 2 .. he i I o 2 3 4 5 First Glume Length (mm) a b , i I .. ! ,i .. ,,'.a ...... ._ : .to.a :: .1 .. [II.. .. 5 ···· .. ·· .. ·············· .. ··· .. ·····.~.··:iii:'! .. r.'J.w····· ................................. e 7 6 4 .. · .. · ... ··.····· ................ : ... ; .. iE~~.:.! ........ _ ...................................... d It ... ,. ..... a: .. :l1-·M • : ! :" *:.3" I I 3 ; I 2+-~~~-,~~~~~~-r~~ 2 3 4 5 6 7 Second Glume Length (mm) Figures 1, 2: 1 Scatter diagram of first-glume length vs. second-glume length for Great Plains collections. Lines a and c represent the points of separation between Mc-Neill's (1979) two species. The gap between lines a and b represents the separation Fernald (1950) creates between his two species (Fernald does not utilize first-glume length). 2. Scatter diagram of second-glume length vs. lowest-lemma length for Great Plains collections. Lines a and d represent the points of separation between Mc-Neill's (1979) two species. The gaps between lines a and b and between d and e represent the separation Fernald (1950) creates between his two species. Table I. Ranges and means for lengths of first glumes, second glumes and lemmas for the Two Rivers, Salt Marsh, and U.N.O. populations. All values for parameters between populations differ significantly (p = 0.05) using the Duncan Multiple Range Test, Student-Newman-Keuls Test, and Scheffe's Test (Allen, 1982). Populations First glume Second Lemma (mm) glume (mm) (mm) Two Rivers 1.8-3.7 3.1-4.9 3.6-4.9 x=2.5 x=4.0 x=4.8 SaltMarsh 2.2-3.4 3.7-5.5 5.0-6.3 x=2.9 x=4.7 x=5.5 U.N.O. 1.5-2.6 2.9-4.3 3.8-4.8 x=2.1 x=3.6 x=4.3 Table II. Measurements used and index values as-signed in the construction of the hybrid indices in Fig. 4. Character First-glume length (mm) Second-glume length (mm) Lowest-lemma length (mm) Total index value Species designation Hybrid index value 0 <2.0 <3.5 <4.0 o L. (asci-cularis Individual population collections Hybrid index value 3 2.0 3.5-4.5 4.0-5.0 3-15 inter-mediate Hybrid index value 6 >2.0 >4.5 > 5.0 18 L. acum-inata A total of 157 plants were collected from three lo-cations in eastern Nebraska. Seventy-five plants were collected along the Platte River at Two Rivers State Recreation Area, Douglas County, Nebraska, on August 12. All plants were collected in wet, sandy soil along the river bank. Cleistogamy was observed in the majority of plants, but some were ob-served to have some anthers exserted on the florets, indicating some chasmogamous reproduction. Thirty-two plants, also largely cleistogamous, were collected in a salt marsh on 27th street in Lincoln, Lancaster County, Nebraska on August 31. Fifty plants were collected in a disturbed habitat in the parking lot of the University of Nebraska at Omaha (U.N.O.), Douglas County, Nebraska, in an area in which the soil appeared to be very dry. Twenty-four E §. .J::. c;, c G) ....J G) E ::l C; "0 c 8 G) rn E §. .J::. c;, c G) ....J ~ ::l C; "2 8 G) rn 5.5 5.0 4.5 4.0 3.5 3.0 2.5 1.5 5.5 5.0 4.5 4.0 3.5 3.0 2.5 1.5 5.5 5.0 • 4.5 4.0-3.5 -3.0 Two Rivers .1 •••• •. ·.·1·· • •• • I!I I,.. · ·.1 II · ••• 1. •• I • 2.0 2.5 3.0 3.5 First Glume Length (mm) Salt Marsh .. -••• • _.: .. • ._ •• 1 • • 2.0 2.5 3.0 3.5 First Glume Length (mm) U.N.O. • iii Lemmas < 4.1 mm 153 4.0 4.0 • Lemmas 4.1-4.9 mm • Lemmas> 4.9 mm 2.5~-----~1----~------r-1----~----~ 1.5 2.0 2.5 3.0 3.5 4.0 First Glume Length (mm) Figure 3. Scatter diagrams plotting first-glume length vs. second-glume length for the Two Rivers, Salt Marsh and U.N.O. populations, with lemma-length categories indi-cated by symbols. en J:: Q) E I '0 ... Q) ~ :::J Z 154 30 Two Rivers 25 20 15 10 5 0 ..... - .. o 3 6 9 12 30 SaltMarsh 25 20 15 10 5 O~--~----~--~--~--~ en J:: Q) E .~ en '0 30 20 I 10 :::J Z o o 3 U.N.O. o 3 6 9 12 6 9 12 Hybrid Index Values 15 18 15 18 15 18 Figure 4. Hybrid index plots for the Two Rivers, Salt Marsh, and U.N.O. populations combining first-glume length, second-glume length, and lemma length. See Table II. of the 50 U.N.O. plants were mature on June 27, and were collected at that time. The remaining 26 plants represented in the U.N.O. data were collected on July 7. No plants from this population were observed to have anthers exserted from the florets. The ranges and means for lengths of first glumes, second glumes and lowest lemmas for these three populations are given in Table I. The three statistical tests applied showed that all three eharac-teristics were significantly different for all three populations. When the three characteristics were considered together in scatter diagrams, each population formed its own distinct cluster, but none of the three populations showed any internal separations (Fig. 3) In the Two Rivers and U.N.O. populations, a number of individuals which were intermediate with respect to lemma length could be seen to be assignable to one species or the other based on glume length. When the characteristics were combined in a hybrid index, each population again was shown to be distinctly different (Table II, Fig. 4). The hybrid index for the Two Rivers population assigned only one specimen to L. fascicularis and nine speci-mens to L. acuminata, the remaining 65 plants be-ing intermediates. The Salt Marsh population had no plants assignable to L. fascicularis, 21 plants assignable to L. acuminata and the remaining 11 as intermediates. Four plants from the U.N.O. were assignable to L. fascicularis, none to L. acuminata, and the remaining 46 as intermediates. CONCLUSIONS Using glume and lemma lengths, the Leptochloa complex in the Great Plains appears to represent a single taxon, but with individual populations sig-nificantly different from other populations. Au-thors basing the separation of species on data ob-tained from a small number of small collections (Dore and McNeill, 1980; McNeill, 1979; Mohlen-brock, 1973) have not observed the continuous range of variation that occurs in reality. Though the num-ber of populations sampled is not reported by Fer-nald in his separation of the taxa, it would appear that he may have based his separation on a few popu-lations as evidenced by the large number of inter-mediate individuals collected for this study. This study indicates that local populations may differ markedly from each other, even when geographical distance between them is not great and particularly when populations exhibit a high frequency of cleis-togamy. ACKNOWLEDGMENTS I am indebted to the members of my graduate committee, David Sutherland, Thomas Bragg, and James Wood for help given in this work, which was completed in partial fulfillment of the requirements for the Master of Arts Degree at the University of Nebraska at Omaha in 1985. David Sutherland also provided assistance in preparing it for publication. LITERATURE CITED Allen, A, editor. 1982. SAS user's guide: basics. Cary, North Carolina, SAS Institute: 921 pp. Bell, C. R. 1967. Plant variation and classifica-tion. Belmont, California, Wadsworth: 135 pp. Dore, W. G., and J. McNeill. 1980. Grasses of On-tario. Hull, Quebec, Research Branch Agricul-ture Canada: 566 pp. Fernald, M. L. 1950. Gray's manual of botany, 8th edition. New York, American Book Company: 1632pp. Gleason, H. G., and A Cronquist. 1963. Manual of vascular plants of northeastern United States and adjacent Canada. New York, Van Nord-strand: 810 pp. McNeill, J. 1979. Diplachne and Leptochloa (Poaceae) in North America. Brittonia 31: 399-404. Mohlenbrock, R. H. 1973. The illustrated flora of Illinois. Grasses: Panicum to Danthonia. Car-bondale and Edwardsville, Illinois, Southern Illinois University Press: 378 pp. 155 

A Taxonomic Study of Variation in Leptochloa Fascicularis (LAM.) Gray in the Central Great Plains

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A Taxonomic Study of Variation in Leptochloa Fascicularis (LAM.) Gray in the Central Great Plains

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