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.

Hilaria swallenii

HABIT Perennial; caespitose. Stolons present. Culms erect; 10–30 cm long. Culm-internodes distally glabrous. Culm-nodes bearded. Leaves mostly basal. Leaf-sheaths scaberulous. Ligule an eciliate membrane; 2–2.2 mm long. Leaf-blades flat, or involute; 4–8 cm long; 1–2 mm wide. Leaf-blade surface ribbed; scabrous; rough on both sides.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 2–8; 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 1–4 cm long. Rhachis obsolete; deciduous from axis.

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

STERILE SPIKELETS Companion sterile spikelets well-developed; containing empty lemmas, or male; oblong; asymmetrical; dorsally compressed; 6.5–8 mm long; as long as fertile; deciduous with the fertile. Companion sterile spikelet glumes united below; coriaceous; thinner on margins; glandular; 7 -veined; tuberculate; lobed; 2 -fid; obtuse; muticous. Companion sterile spikelet lemmas 2; exserted from glumes; muticous.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets oblong; laterally compressed; 6.5–8 mm long; falling entire; deciduous with accessory branch structures.

GLUMES Glumes connate along margins below; shorter than spikelet; firmer than fertile lemma. Lower glume oblong; asymmetrical; coriaceous; much thinner above; much thinner on margins; black; glandular; 1-keeled; 7 -veined. Lower glume surface tuberculate. Lower glume apex lobed; 2 -fid; awned; 1 -awned. Lower glume awn 5–6 mm long. Upper glume oblong; asymmetrical; coriaceous; much thinner above; with membranous margins; black; glandular; 1-keeled; 7 -veined. Upper glume surface tuberculate. Upper glume apex lobed; 2 -fid; awned; 1 -awned. Upper glume awn 5–6 mm long.

FLORETS Fertile florets female. Fertile lemma ovate; laterally compressed; 6–7.5 mm long; cartilaginous; keeled; 3 -veined. Lemma apex caudate.

FLOWER Anthers 3; 3–3.5 mm long.

DISTRIBUTION North America: south-central USA and Mexico.

NOTES Cynodonteae. Swallen.

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