Culms 40-130 cm, to 1 mm thick at the nodes, unbranched, leafy for 50%
of their height. Sheaths glabrous; collars glabrous; ligules
0.2-0.4 mm, entire; blades (8)15-35(40) cm long, 3-8(11) mm wide, linear-lanceolate,
usually glabrous, sometimes sparsely pilose adaxially. Panicles (7)12-35(47)
cm, contracted, erect; branches ascending to appressed; axils of panicle
branches glabrous; pedicels 0.5-2.5 mm. Spikelets 4-9 mm long,
2-6 mm wide, with (2)3-5(7) florets, lower 1(2) florets sterile, fertile florets
divergent to 45°. Lower glumes 1.3-3 mm, (1)3-5-veined; upper glumes
1.3-2.5 mm, 3-5-veined; calluses glabrous; fertile lemmas 2.9-4.5
mm, straight, 3-7-veined, keels not winged, apices scabridulous; paleas
2.3-3 mm; anthers 1.3-1.5 mm, the length invariant within a spikelet. Caryopses
1.9-2.2 mm, exposed at maturity. 2n =24.
Chasmanthium laxum is almost completely sympatric with C.
sessiliflorum in the southeastern United States, growing in similar habitats
but extending further into sphagnous stream heads, pine flatwoods, and pine savannahs.
Yates (1966b) reported seeing putative, naturally occurring hybrids between C. ornithorhynchum and C. laxum along streams of the outer coastal plain of Mississippi and
Louisiana. In general appearance, the hybrids resemble C. laxum, their
most striking difference being the enlarged, sterile spikelets.
Culms 60-150 cm, (1)2-3.5 mm thick at the nodes, unbranched, leafy for
40% of their height. Sheaths pilose; collars pilose; ligules
0.2-0.3 mm, entire; blades (15)20-50 cm long, 4.5-9.5(15) mm wide, linear-lanceolate,
sparsely pilose adaxially. Panicles (9)20-70 cm, contracted or open, erect;
branches tightly appressed or ascending to strongly divergent; axils
of panicle branchesglabrous or scabridulous at the edges; pedicels
0.3-2.5(5) mm. Spikelets 4-10 mm long, 6-9 mm wide, with 4-7(8) florets,
lower 1(2) florets sterile, fertile florets divergent to 80°. Lower glumes
1.2-2.7 mm, 3-5-veined; upper glumes 1.4-2.2 mm, 3-5-veined; calluses
glabrous; fertile lemmas 3.5-5.9 mm, usually curved or irregularly contorted,
7-9-veined, keels not winged, apices scabridulous; paleas 2.8-4 mm; anthers
(0.8)1.3-1.6 mm, varying in length within a spikelet. Caryopses 2-2.5 mm,
exposed at maturity. 2n =24.
Chasmanthium sessiliflorum grows in rich woods, meadows, and swamps, especially
on the coastal plain. It grows throughout most of the southeastern United States.
Tufted on short rhizomes, 5-15 dm; sheaths essentially glabrous except for the ciliate margins; blades elongate, 3-7 mm wide, attenuate into a long, almost filiform tip; infl virgate, 1.5-4 dm; spikelets sessile or short-pedicellate, 3-5(-7)-fld, 5-10 mm, reverse- triangular or V-shaped; glumes 1.5-3 mm, equal or subequal; lemmas (the lower 1 or 2 empty) acuminate, 5-7(-9)-veined, with glabrous callus; palea shorter than the lemma; grain 2-3 נ1-2 mm, exposed, widely spreading the lemmas and paleas at maturity; 2n=24. Woods, meadows, and swamps; Fla. to Tex., n. to L.I., N.J., Ky., and s. Mo. (Uniola l.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Much like no. 2 [Chasmanthium laxum (L.) H. O. Yates], but the sheaths villous at the summit or throughout; lvs mostly 6-12 mm wide; 2n=24. Moist open woods and streambanks; Fla. to Tex., n. to se. Va., Tenn., and e.c. Mo. (Uniola s.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.