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

CHASMANTHIUM/POACEAE
865
[C. carolinianus of authors, not Walter, C. incertus M.A. Curtis, C. parviceps Shinners, C.
pauciflorus Benth.] We are following Jones et al. (1997), Kartesz (1999), and Stieber and Wipff
(2003) for nomenclature of this species. It is considered to be a noxious weed in AZ, CA, and NV
(Kartesz 1999). � m/282
CHASMANTHIUM Link WOOD-OATS
Perennials, ours rhizomatous; ligule in ours a minute ciliate membrane; leaf blades broad, flat;
inflorescence an open or contracted panicle (rarely a raceme); spikelets (2–)3–many-flowered,
laterally flattened, sometimes conspicuously so, disarticulating above the glumes and between
the florets; glumes shorter than lemmas; lower 1–4 florets sterile.
AA C3 genus of 5 species (Sánchez-Ken & Clark 2003) endemic to North America; in the past
it was recognized as part of the genus Uniola, which includes U. paniculata L., a coastal dune
species known as SEA OATS. However, it is now recognized that Chasmanthium and Uniola,
while superficially similar, belong in different subfamilies. Chasmanthium is the only genus of
subfamily Centothecoideae that occurs in East TX. (Greek: chasme, gaping or yawn, and anthus,
flower, presumably from the form of the spikelets—the lemmas and paleas gap and expose the
grain at maturity) (subfamily Centothecoideae, tribe Centotheceae)
REFERENCES: Yates 1966a, 1966b; Brown & Smith 1974; Clark 1990; Tucker 1990; Wipff & Jones
1994 [1995]; Sánchez-Ken & Clark 2003.
1. Inflorescence branches drooping; pedicels 10–30 mm long; spikelets (10–)20–50 mm long, 6–
17(–26)-flowered ________________________________________________________________ C. latifolium
1. Inflorescence branches erect or ascending; pedicels at most 5 mm long, usually much less; spikelets
4–10(–18) mm long, 3–7-flowered.
2. Leaf sheaths glabrous or nearly so; collar of leaf sheaths glabrous; culms 1 mm thick or less at
the nodes; lemmas of fertile florets straight, with 3–7 veins ________________________________ C. laxum
2. Leaf sheaths (at least lower) usually long-pubescent or hirsute (rarely glabrous); collar of leaf
sheaths pubescent; culms (1–)2–3.5 mm thick at the nodes; lemmas of fertile florets usually
curved or irregularly contorted, with 7–9 veins ___________________________________ C. sessiliflorum
Chasmanthium latifolium (Michx.) H.O. Yates, (broad-leaved), WILD OATS, BROAD-LEAF WOOD-OATS,
INLAND SEA-OATS, BROAD-LEAF CHASMANTHIUM, CREEK-OATS, INDIAN WOOD-OATS. Glabrous perennial,
0.4–1.5 m tall; culms leafy to 4/5 of their height; leaf blades 8–20(–30) mm wide; spikelets
conspicuously flat, very wide (6–20 mm). Along streams and in moist woods, usually in shade;
one of our most common woodland grasses; widespread in e 1/2 of TX; e U.S. from PA s to FL w to
WI and TX. Jun–Sep. [Uniola latifolia Michx.] The large spikelets make this an excellent example
to use in demonstrating spikelet structure to students; the dried inflorescences are also sometimes
used ornamentally in dried flower arrangements. Because of its beauty and shade tolerance, this
species is becoming increasingly used as an ornamental in native plant landscapes. According to
Sánchez-Ken and Clark (2003), flowering is sometimes cleistogamous. m/282
Chasmanthium laxum (L.) H.O. Yates, (loose), SLENDER WOOD-OATS, SLENDER CHASMANTHIUM.
Clumped, essentially glabrous perennial 40–130 cm tall; culms usually leafy for ca. 1/2 their
height; leaf blades (8–)15–35(–40) cm long, usually 3–8(–11) mm wide; panicle branches appressed
to ascending; spikelets flat, (2–)3–5(–6) mm wide, usually with 3–5 florets. Moist, usually
sandy areas; Pineywoods and Post Oak Savannah; also n Gulf Prairies and Marshes; e U.S.
from NY s to FL w to MO, OK, and TX; Jun–Nov. [Uniola laxa (L.) Britton, Sterns, & Poggenb.]
Chasmanthium sessiliflorum (Poir.) H.O. Yates, (sessile-flowered), NARROW-LEAF WOOD-OATS,
LONG-LEAF WOOD-OATS, LONG-LEAF CHASMANTHIUM. Clumped perennial usually 0.7–1.5 m tall,
usually with pubescence, similar to C. laxum; culms usually leafy for ca. 2/5 their height; leaf
blades (15–)20–50 cm long, 4.5–12(–15) mm wide; panicle branches appressed to ascending to