Chasmanthium laxum

(L.) H.O. Yates
Common names: Slender chasmanthium
Endemic
Synonyms: Uniola laxa
Treatment appears in FNA Volume 25. Treatment on page 346.

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.

Distribution

Md., N.J., Okla., Miss., Tex., La., Pa., Mo., Del., Ala., D.C., Tenn., N.C., S.C., Va., Ark., Ga., N.Y., Ky., Fla.

Discussion

Chasmanthium laxum is almost completely sympatric with C. sessiliflorum in the southeastern United States, growing in similar habitats but extending farther into sphagnous stream heads, pine flatwoods, and pine savannahs. Yates (1966b) reported seeing putative, naturally occurring hybrids between Chasmanthium 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.

Selected References

None.

Lower Taxa

None.

"leafy" is not a number."decumbent" is not a number.

... more about "Chasmanthium laxum"
0.13 cm1.3 mm <br />0.0013 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
scabridulous +
Acuminate (?) +  and Acute (?) +
J. Gabriel Sanchez-Ken +  and Lynn G. Clark +
(L.) H.O. Yates +
1 (?) +  and 3 (?) +
keeled +  and rounded +
pseudopetiolate +  and branching +
divergent +  and parallel +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
not pseudopetiolate +
15 cm150 mm <br />0.15 m <br /> (35 cm350 mm <br />0.35 m <br />) +
pilose +  and glabrous +
linear-lanceolate +
3mm;8mm +
ascending;appressed +
spikelike +
brown +  and reddish-black or black +
compressed +
0.19 cm1.9 mm <br />0.0019 m <br /> (0.22 cm2.2 mm <br />0.0022 m <br />) +
fusoidlike +
Slender chasmanthium +
ascending +  and erect +
40 cm400 mm <br />0.4 m <br /> (130 cm1,300 mm <br />1.3 m <br />) +
not woody +
0 cm0 mm <br />0 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
Md. +, N.J. +, Okla. +, Miss. +, Tex. +, La. +, Pa. +, Mo. +, Del. +, Ala. +, D.C. +, Tenn. +, N.C. +, S.C. +, Va. +, Ark. +, Ga. +, N.Y. +, Ky. +  and Fla. +
less +  and 1/3 +
large +  and small +
capillary +
pistillate +  and staminate +
sometimes longer +
basal +  and distal +
rudimentary +
3 +  and 5 +
fertile +  and sterile +
round +  and compressed +
reduced +
(2)3-9-veined +
subtending +
acute +  and acuminate +
subequal +
membranous +
uncinate +
subbasal +  and basal +
hollow +  and solid +
straight +
compressed-keeled +
0.29 cm2.9 mm <br />0.0029 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.04 cm0.4 mm <br />4.0e-4 m <br />) +
membranous +
inconspicuous +
0.13 cm1.3 mm <br />0.0013 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
concealed +  and prominent +
2 +  and 1 +
well-developed +
2-keeled +  and gibbous +
0.23 cm2.3 mm <br />0.0023 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
7 cm70 mm <br />0.07 m <br /> (?) +
12 cm120 mm <br />0.12 m <br /> (35 cm350 mm <br />0.35 m <br />) +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
dry +  and fleshy +
staminate +, pistillate +, subsessile +, pedicellate +  and solitary +
0.4 cm4 mm <br />0.004 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
1 +  and 60 +
compressed +
0.4 cm4 mm <br />0.004 m <br /> (5 cm50 mm <br />0.05 m <br />) +
2mm +  and 6mm +
free +  and fused +
triangular +  and dome--shaped +
Uniola laxa +
Chasmanthium laxum +
Chasmanthium +
species +
membranous +
0.13 cm1.3 mm <br />0.0013 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
plant +, colonial +  and cespitose +
aquatic +  and terrestrial +
pilose +, scabrous +  and glabrous +