IDENTIFICATION OF MISSOURI SPECIES OF THE TRIBE DESMODIEAE (FABACEAE) USING VEGETATIVE CHARACTERS JAY A. RAVEILL1 Abstract. The legume tribe Desmodieae in Missouri consists of four genera: Desmodium (17 species and one named hybrid), Hylodesmum (3 species), Kummerowia (2 species), and Lespedeza (11 species). The genera and species are dis- tinguished mainly by reproductive features of the mature fruit which are not present during most of the growing season. The two largest genera, Desmodium and Lespedeza, are considered especially “difficult” groups because spe- cies can be difficult to distinguish, even with complete specimens. This paper provides a key to the Missouri species of this tribe based largely on vegetative traits present throughout most of the growing season. Keywords: Flora of Missouri, Desmodieae, Desmodium, Lespedeza, Kummerowia, Hylodesmum, key to vegetative speci- mens. The tribe Desmodieae (Benth.) Hutch., as pres- dium (Steyermark 1963), based partly on conspicu- ently recognized, includes 30 genera and approxi- ous differences in fruit; the former genus with mately 527 species (Ohashi 2005). The number one-seeded loments and the latter with mul- of genera is up from 27 previously recognized by tiseeded loments. In this paper, one segregate Ohashi et al. (1981) due to the splitting out of sev- genus has been split from each, Kummerowia eral small genera, primarily from Desmodium Desv. Schindl. from Lespedeza and Hylodesmum H. Ohashi Four genera traditionally placed in this tribe have & R.R. Mill from Desmodium. been reassigned to other tribes based on molecular The two annual species of a broadly defined evidence (Kajita et al. 2001; Lavin et al. 2001). genus Lespedeza, both native to east Asia but The more narrowly circumscribed Desmodieae is widely introduced in North America, may be dis- nested within the tribe Phaseoleae, but the sam- tinct enough to merit generic recognition under pling within the Desmodieae has not been exten- the name Kummerowia (Schindler 1912). Traits of sive enough to determine if this tribe is a mono- Kummerowia not shared by Lespedeza include an an- phyletic lineage (Wojciechowski 2003). A synapo- nual habit, prominent secondary veins that diverge morphy that helps to define the tribe on a molecu- from the midrib at right angles and seldom lar level is the absence of the chloroplast rpl2 in- branch, broader stipules, and near absence of tron (Bailey et al. 1997). petiolules. The highly reduced axillary infloren- The tribe Desmodieae has a nearly worldwide scences have been variously considered as funda- distribution but is absent from Europe and west- mentally different from Lespedeza (Akiyama & ern North America. Both the generic and species Ohba 1985) or rather similar to Lespedeza cuneata diversity is greatest in east Asia (Ohashi 2005) but (Dum. Cours.) G. Don especially (Nemoto & species-rich radiations have occurred in two gen- Ohashi 1993). Many authors have recently recog- era, Desmodium and Lespedeza Michx., in eastern nized Kummerowia as distinct from Lespedeza in phy- North America (Isely 1998). logenetic treatments (Bailey et al. 1997; Doyle et Traditionally, Missouri species of this tribe have al. 1995; Endo & Ohashi 1998; Kajita et al. 2001) been placed in two genera, Lespedeza and Desmo- and regional floras (e.g., Ohwi 1965; Isely 1990, The survey of herbarium specimens for this project was done in preparation of treatments of the members of this tribe for volume three of Steyermark’s Flora of Missouri by George Yatskeivych (MO) and some measurements were taken from the draft of the species descriptions prepared for this work. Partial funding for the treatments was provided by the Missouri De- partment of Conservation. Dan Drees and Susan Farrington (Missouri Department of Conservation) alerted me to the need for keys to vegetative legumes. I thank Michael Vincent (Miami University), Michael Woods (Troy State University), Steve Wilson (University of Central Missouri), and an anonymous reviewer for improvements to a previous version of this paper. 1 Department of Biology and Earth Science, University of Central Missouri, Warrensburg, MO 64093. Email: [email protected] Vulpia, Vol. 5, 2006, pp. 14–22. © The North Carolina State University Herbarium, 2006. 15 VULPIA Vol. 5 1998; Jones et al. 1997; Wunderlin 1998; Rhoades sarum glutinosum Muhl. ex Willd. to Desmodium & Block 2000), although there are exceptions (e.g., based on a direct translation of a description of Magee & Ahles 1999; Turner 2003; Jones 2005). Hedysarum glutinosum, the argument used by Schu- The more narrowly defined genus Lespedeza con- bert (1942), or if the entity described by Wood sists of 11 species in Missouri, eight are native and should be considered a new species that would three naturalized members of the flora then block the later valid transfer by Schindler (Yatskievych & Turner 1990). (1926), as discussed by Isely (1951). Three Missouri species are affected by a recent Members of this tribe are widespread and com- proposal to split 14 species out of Desmodium and mon components of the flora of Missouri. The place them into the newly described genus, Hy- species in Lespedeza and Desmodium can present lodesmum (Ohashi & Mill 2000). These species, D. significant identification difficulty (Schubert 1950a glutinosum (Muhl. ex Willd.) Alph. Wood, D. nudiflo- & b; Clewell 1966a & b). The species often occur rum (L.) DC., and D. pauciflorum (Nutt.) DC., are together in nature and interspecific hybridization distinct from the remainder of the North Ameri- has been well documented in Lespedeza (Clewell can Desmodium species and previously had been 1964, 1966a & b) and to a lesser extent within Des- placed in section Podocarpium Benth. (Isley 1951) or modium (Raveill 1995, 2002). Typically, keys to series Americana B.G. Schub. (Schubert 1950a & genera and species rely on reproductive features b). The segregation of Hylodesmum renders moot a that are generally not present until mid to late nomenclatural issue involving Desmodium glutino- summer. To aid in identification, a key that uses sum. The long-standing question has been if primarily vegetative traits is presented that does Alphonso Wood (1845) intended to transfer Hedy- not require that genus be initially determined. METHODS Specimens were examined from eight herbaria & Mill 2002); 2) the use of the name Lespedeza vio- (KANU, MWSJ, MO, NEMO, SMS, UMO, locea (L.) Pers. as a replacement for L. intermedia WARM and Powell Botanical Gardens, Kingsville) Britton, and L. frutescens (L.) Hornem. for the which included relevant Missouri collections taxon traditionally called L. violacea (Reveal & Bar- (Raveill 2005). Most measurements were taken rie 1991); 3) a sporadically occurring hybrid be- from MO or UMO specimens collected in Mis- tween D. rotundifolium (Michx.) DC. and D. panicu- souri. However for the rarest species, D. ochroleu- latum (L.) DC. (or related species) has been for- cum M.A. Curtis ex Canby, D. strictum (Pursh) DC., mally recognized as D. x humifusum (Muhl. ex and D. viridiflorum (L.) DC., measurements were Willd.) L.C. Beck; 4) the variety, D. cuspidatum var taken from specimens collected outside of the longifolium (Torr. & A.Gray) B.G. Schub. is men- state. tioned in the key but is not formally recognized; 5) Nomenclature follows Yatskievych & Turner five named hybrids in Lespedeza are not included (1990) except for the following: 1) the recognition since they are not easily characterized using vege- of Hylodesmum as distinct from Desmodium (Ohashi tative features. RESULTS AND DISCUSSION A key to the species of the tribe Desmodieae blade as a distinct, mucronate tip; while in the lat- (Fabaceae: Faboideae) using primarily vegetative ter two, the midrib does not extend beyond the traits is presented. The construction of the key blade. Stipels are absent in Lespedeza, Kummerowia, does not require that species initially be deter- and Hylodesmum (except for H. nudiflorum (L.) H. mined to genus, although the genera can be distin- Ohashi & R.R. Mill) but are usually apparent in guished using vegetative characters. One feature Desmodium. that distinguishes Lespedeza and Kummerowia from Two of the genera, Desmodium and Lespedeza, are Hylodesmum and Desmodium is the leaf tip. In the traditionally considered to have species that are two former genera, the midrib extends beyond the difficult to distinguish (Isely 1998) and when re- 2006 Raveill, Vegetative Identification of Missouri Desmodieae 16 productive characters are excluded, identification Other keys based on sterile material are available can be even more problematic. Two pairs of spe- for some members of this tribe. An extensive key cies, Lespedeza frutescens/L. violacea and Desmodium to vegetative legumes was presented by Fassett nuttallii (Schindl.) B.G. Schub./D. viridiflorum re- (1939) for all the Wisconsin members of the fam- quire reproductive structures to make conclusive ily. Twelve members of the tribe Desmodieae identifications. Between several other taxa, no were included, but the nomenclature has become single vegetative trait is definitive and a suite of dated. Keys for vegetative Desmodium (including overlapping characters must be considered. Hy- Hylodesmum) species are available for North Caro- bridization may be responsible for the occurrence lina species (Krings 2004) and for species found in of a limited number of specimens that blur the the North-central United States (Isely 1955). The distinction between species. Reproductive charac- former emphasized