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Descriptions

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

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

Hilaria jamesii

HABIT Perennial; caespitose. Rhizomes short. Culms erect; 20–65 cm long. Culm-internodes distally glabrous. Culm-nodes pubescent. Leaf-sheaths smooth, or scaberulous. Leaf-sheath oral hairs ciliate. Ligule an eciliate membrane; 2–3 mm long; lacerate. Leaf-blades involute; 2–20 cm long; 2–4 mm wide; stiff. Leaf-blade surface ribbed; scabrous; rough on both sides.

INFLORESCENCE Inflorescence composed of racemes.

Racemes numerous; borne along a central axis; closely spaced; in a multilateral false spike; oblong; unilateral; 0.6–0.8 cm long; bearing a triad of spikelets. Central inflorescence axis 2–6 cm long; pubescent. Rhachis obsolete; deciduous from axis. Raceme-bases brief; pilose.

Spikelets in threes. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 2 in the cluster.

STERILE SPIKELETS Companion sterile spikelets well-developed; male; oblong; asymmetrical; dorsally compressed; 5–7 mm long; shorter than fertile; deciduous with the fertile. Companion sterile spikelet glumes free; membranous; 3–7 -veined; ciliolate on margins; lobed; 2 -fid; awned; one glume awned; with 6–8 mm long awn. Companion sterile spikelet lemmas 3; exserted from glumes; 5–7 mm long; muticous.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets oblong; laterally compressed; 6–8 mm long; falling entire; deciduous with accessory branch structures.

GLUMES Glumes free; shorter than spikelet. Lower glume lanceolate; asymmetrical; chartaceous; pallid; 1-keeled; 7 -veined. Lower glume primary vein ciliate. Lower glume surface pubescent. Lower glume margins ciliate. Lower glume apex lobed; 5 -fid; awned; 7 -awned. Lower glume awn 3–5 mm long. Upper glume lanceolate; asymmetrical; 0.75 length of adjacent fertile lemma; chartaceous; pallid; 1-keeled; 7 -veined. Upper glume primary vein ciliate. Upper glume surface puberulous. Upper glume margins ciliate. Upper glume apex lobed; 5 -fid; awned; 7 -awned. Upper glume awn 3–5 mm long.

FLORETS Fertile florets bisexual. Fertile lemma lanceolate; laterally compressed; 6–8 mm long; cartilaginous; keeled; 3 -veined. Lemma apex dentate; 2 -fid; obtuse; awned; 1 -awned. Principal lemma awn from a sinus; 2–3 mm long overall.

FLOWER Lodicules 2; 0.1–0.2 mm long. Anthers 3; 3 mm long.

DISTRIBUTION North America: northwest USA, southwest USA, and south-central USA.

NOTES Cynodonteae. Swallen.

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