TaxonIllustrator 
FNA25 P132 Chasmanthium pg 347.jpegChasmanthium latifolium
Chasmanthium nitidum
Chasmanthium ornithorhynchum
Hana Pazdírková
Linda A. Vorobik
Hana Pazdírková
Linda A. Vorobik
Hana Pazdírková
Linda A. Vorobik
FNA25 P133 Chasmanthium pg 348.jpegChasmanthium sessiliflorum
Chasmanthium laxum
Hana Pazdírková
Linda A. Vorobik
Hana Pazdírková
Linda A. Vorobik

Plants perennial; cespitose or loosely colonial, rhizomatous. Culms 35-150 cm, simple or branched. Leaves cauline; ligules membranous, ciliate; blades not pseudopetiolate, flat. Panicles open or contracted, sometimes becoming racemose distally; disarticulation above the glumes and between the florets. Spikelets 4-50 mm, laterally compressed, with 2-many florets, lower 1-4 florets sterile. Glumes 2, subequal, shorter than the spikelets, glabrous, (2) 3-9-veined, acute to acuminate; lemmas glabrous, 3-15-veined, compressed-keeled, keels serrate or ciliate, apices acuminate to acute, entire (rarely bifid); paleas glabrous, gibbous basally, 2-keeled, keels winged, wings glabrous, scabrous, or pilose; lodicules 2, fleshy, cuneate, 2-4-veined, lobed-truncate; anthers 1; ovaries glabrous; styles 2; style-branches 2, plumose, reddish-purple at anthesis. Caryopses 1.9-5 mm, laterally compressed, brown to reddish-black or black, x = 12.

Distribution

Del., Wis., W.Va., Fla., N.J., Tex., La., N.C., Tenn., S.C., Pa., N.Y., D.C, N.Mex., Va., Ala., Ark., Ill., Ga., Ind., Iowa, Ariz., Md., Kans., Okla., Ohio, Mo., Mich., Miss., Ky.

Discussion

Chasmanthium, a genus of five species endemic to North America, grows primarily in the southeastern and south-central parts of the United States. It was formerly included in Uniola, but it is now recognized as a distinct genus.

Key

1 Panicle branches nodding or drooping; pedicels 10-30 mm long; calluses pilose; lower glumes 4.2-9.1 mm long; keels of fertile lemmas winged, the wings scabrous to pilose their full length; caryopses 2.9-5 mm long Chasmanthium latifolium
1 Panicle branches erect or ascending; pedicels 0.5-2.5(5) mm long; calluses glabrous; lower glumes 1.2-5 mm long; keels of fertile lemmas not winged, scabridulous toward or at the apices; caryopses 1.9-3 mm long. > 2
2 Spikelets 9.5-24 mm long; fertile lemmas 9-13-veined; caryopses enclosed at maturity; blades 7-16(33) cm long, lanceolate-fusiform; culms leafy for 80% of their height. > 3
3 Axils of the panicle branches scabrous; fertile florets diverging to 45° from the rachilla; sterile florets (0)1(2); lower glumes 3.1-5 mm long, 7-9-veined; ligules entire Chasmanthium nitidum
3 Axils of the panicle branches pilose; fertile florets diverging to 85° from the rachilla; sterile florets 2-4; lower glumes 2.5-2.9 mm long, 2-3-veined; ligules irregularly laciniate Chasmanthium ornithorhynchum
2 Spikelets 4-10 mm long; fertile lemmas 3-9-veined; caryopses exposed at maturity; blades (8)20-50 cm long, linear-lanceolate; culms leafy for 40-50% of their height. > 3
4 Collars and sheaths pilose; culms (1)2-3.5 mm thick at the nodes; fertile lemmas 7-9-veined, usually curved or irregularly contorted Chasmanthium sessiliflorum
4 Collars and sheaths glabrous; culms to 1 mm thick at the nodes; fertile lemmas 3-7-veined, straight Chasmanthium laxum

"wide" is not a number."decumbent" is not a number.

... more about "Chasmanthium"
acuminate +  and acute +
J. Gabriel Sanchez-Ken +  and Lynn G. Clark +
1 (?) +  and 3 (?) +
keeled +  and rounded +
pseudopetiolate +  and branching +
divergent +  and parallel +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
not pseudopetiolate +
usually linear +  and lanceolate occasionally ovate +
spikelike +
brown +  and reddish-black or black +
compressed +
0.19 cm1.9 mm <br />0.0019 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
fusoidlike +
branched +  and simple +
0 cm0 mm <br />0 m <br /> (400 cm4,000 mm <br />4 m <br />) +
ascending +  and erect +
35 cm350 mm <br />0.35 m <br /> (150 cm1,500 mm <br />1.5 m <br />) +
not woody +
Del. +, Wis. +, W.Va. +, Fla. +, N.J. +, Tex. +, La. +, N.C. +, Tenn. +, S.C. +, Pa. +, N.Y. +, D.C +, N.Mex. +, Va. +, Ala. +, Ark. +, Ill. +, Ga. +, Ind. +, Iowa +, Ariz. +, Md. +, Kans. +, Okla. +, Ohio +, Mo. +, Mich. +, Miss. +  and Ky. +
less +  and 1/3 +
large +  and small +
capillary +
pistillate +  and staminate +
sometimes longer +
basal +  and distal +
rudimentary +
2 +  and many +
round +  and compressed +
reduced +
(2)3-9-veined +
subtending +
acute +  and acuminate +
subequal +
membranous +
uncinate +
subbasal +  and basal +
hollow +  and solid +
compressed-keeled +
membranous +
inconspicuous +
concealed +  and prominent +
2 +  and 1 +
well-developed +
2-keeled +  and gibbous +
dry +  and fleshy +
yates1966b +  and yates1966c +
staminate +, pistillate +, subsessile +, pedicellate +  and solitary +
1 +  and 60 +
compressed +
0.4 cm4 mm <br />0.004 m <br /> (5 cm50 mm <br />0.05 m <br />) +
free +  and fused +
triangular +  and dome--shaped +
Gramineae +
Chasmanthium +
Poaceae tribe Centotheceae +
membranous +
plant +, colonial +  and cespitose +
aquatic +  and terrestrial +
pilose +, scabrous +  and glabrous +