keys to the vascular plants of east texas - Botanical Research ...

LEPTOCHLOA/POACEAE 967
Leersia oryzoides (L.) Sw., (like rice—Oryza), RICE CUT GRASS. Rhizomatous perennial, the rhizomes
slender, scaly, the scales not imbricate; culms (0.5–)1–1.5 m tall, erect or sprawling and
ascending; leaf blades usually 6–11 mm wide; inflorescence branches usually numerous, naked
of spikelets for ca. 1/3 their length; spikelets (1.3–)1.5–2 mm wide; lemma and palea ciliate on
keel and hispid over surface; stamens 3. Marshes, other wet places, sometimes in wet wooded
areas; widespread in TX; s Canada and throughout the U.S. Usually Sep–Nov. Late-season inflorescences
bearing cleistogamous spikelets are reported to remain completely or mostly enclosed
by the upper leaf sheaths (Tucker 1988; Yatskievych 1999).
Leersia virginica Willd., (of Virginia), WHITE GRASS, VIRGINIA CUT GRASS. Rhizomatous perennial,
the rhizomes stouter than culm base, with imbricate scales; culms 0.5–1.2 m tall; leaf blades
usually 3–8 mm wide, rarely wider; inflorescence branches few, 1 per node, widely spaced, long
and slender, to 8–12 cm long, naked for 1/3 to more than 1/2 their length; lemma and palea minutely
ciliate on veins and sometimes minutely hispid over surface; stamens 2. Ditches, moist
areas; widespread in East TX w to e Edwards Plateau; se Canada and throughout e U.S. w to ND
and TX. May–Nov. [Homalocenchrus virginicus (Willd.) Britton] This species is superficially
similar to Microstegium vimineum (Mehrhoff 2000)—see discussion under that species.
LEPTOCHLOA P. Beauv. SPRANGLETOP, FEATHER GRASS
Annuals or perennials; inflorescence a panicle or subdigitate cluster of spicate branches; spikelets
usually with 3–12 bisexual florets, sessile or nearly so, overlapping in 2 rows on 1 side of a
nearly terete branch, disarticulating above the glumes and between florets; lemmas in ours
awnless or with a short awn to 1.5 mm long.
AA C4 genus of 32 species (including those sometimes segregated into Diplachne) (Snow 1997,
2003a) of warm temperate and tropical areas of the New World, Africa, Asia, and Australia;
some are used as fodder while a number are considered significant weeds (Watson & Dallwitz
1992). Phillips (1982) discussed generic boundaries and concluded that Diplachne (which
would include a number of East TX species) should be recognized at the generic level; more recently,
research by Snow (e.g., 1998b) suggested that these species should be recognized in
Leptochloa. Thorough revisionary work on the genus by Snow (1997, 1998a) has resulted in a
substantial number of name changes in the genus; his classification is followed here. (Greek:
leptos, slender, and chloa, grass, from the slender inflorescence branches) (subfamily
Chloridoideae, tribe Cynodonteae)
REFERENCES: Valls 1978; McNeill 1979; Phillips 1982; Snow & Davidse 1993, 1998; Nicora 1995;
Snow 1996, 1997, 1998a, 1998b, 2003a; Peterson et al. 1997; Yatskievych 1999.
1. Lemmas 1–1.6(–2) mm long; spikelets 1.5–3.5(–4) mm long, with 2–4 florets; leaf sheaths usually
pilose with papilla-based hairs (L. panicea) OR not so (L. nealleyi).
2. Leaf sheaths usually pilose with papilla-based hairs; inflorescence branches variable in length,
(2–)4–15 cm long, but at least some usually � 4 cm long, spreading or spreading-ascending
(even when � 4 cm long), the inflorescence thus not conspicuously narrow; species widespread
and abundant in East TX ____________________________________________________ L. panicea
2. Leaf sheaths glabrous or minutely scabrous, but without papilla-based hairs; inflorescence
branches usually 1.5–4(–6) cm long, usually � appressed to main axis, making the inflorescence
conspicuously narrow; species known only from s boundary of East TX _______________ L. nealleyi
1. Lemmas (1.5–)2.3–5 mm long; spikelets (2–)3–12 mm long, with 3–13 florets; leaf sheaths glabrous
to pilose, any hairs present not papilla-based.
3. Tip of lemmas appearing chopped off, usually notched, awnless; anthers 1–1.6 mm long; some
inflorescences usually completely hidden in the lower leaf sheaths (in addition to the exserted
inflorescences) ______________________________________________________________ L. dubia
3. Tip of lemmas not appearing chopped off, blunt to acute or acuminate (but may be slightly