GrassBase - The Online World Grass Flora


W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson

© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.

Chasmanthium laxum

HABIT Perennial; caespitose. Rhizomes short; knotty. Culms 70–150 cm long. Leaf-sheaths glabrous on surface (rarely), or pubescent, or hirsute. Ligule a ciliolate membrane. Collar pubescent. Leaf-blades 10–40 cm long; 4–12 mm wide. Leaf-blade surface pilose; sparsely hairy; hairy adaxially.

INFLORESCENCE Inflorescence a panicle.

Panicle contracted, or glomerate; linear; interrupted; 15–50 cm long. Primary panicle branches 0.5–9 cm long.

Spikelets solitary. Fertile spikelets pedicelled, or sessile.

FERTILE SPIKELETS Spikelets comprising 1–2 basal sterile florets; 2–4 fertile florets; with diminished florets at the apex. Spikelets cuneate; laterally compressed; 5–8 mm long; 3–5 mm wide; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes definite.

GLUMES Glumes persistent; similar; shorter than spikelet. Lower glume ovate; 1–2.5 mm long; 1 length of upper glume; herbaceous; 1-keeled; 1–3 -veined. Lower glume apex acute. Upper glume ovate; 1–2.5 mm long; 0.33–0.5 length of adjacent fertile lemma; herbaceous; 1-keeled; 3 -veined. Upper glume apex acute.

FLORETS Basal sterile florets similar; barren; without significant palea; persisting on inflorescence. Lemma of lower sterile floret similar to upper glume; ovate; 1.5–2.5 mm long; herbaceous; 1-keeled; 3–5 -veined; acute. Fertile florets increasing in size upwards. Fertile lemma ovate; 3–5 mm long; herbaceous; keeled; 7–9 -veined. Lemma apex acuminate. Palea gaping; bowed outwards; 0.8 length of lemma; 2 -veined. Palea keels winged; narrowly winged; scabrous. Apical sterile florets distinct from fertile; 1 in number; male; linear; 3 mm long.

FLOWER Lodicules 2; cuneate; fleshy. Anthers 1; 1.5–2 mm long.

FRUIT Caryopsis with adherent pericarp; ovoid; laterally compressed; exposed between gaping lemma and palea at maturity; 2–3 mm long. Embryo 0.5 length of caryopsis.

DISTRIBUTION North America: north-central USA, northeast USA, south-central USA, and southeast USA.

NOTES Centotheceae. Gould.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.