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 annua

HABIT Annual; caespitose. Culms erect, or geniculately ascending; slender; 40–50(–60) cm long; rooting from lower nodes. Culm-nodes bearded. Lateral branches ample. Ligule a ciliolate membrane; 2–3 mm long. Leaf-blades 10–20(–30) cm long; 3.5–5 mm wide. Leaf-blade surface glabrous, or pilose; hairy adaxially; with tubercle-based hairs. Leaf-blade margins scabrous.

INFLORESCENCE Inflorescence composed of racemes.

Racemes borne along a central axis; closely spaced; in a multilateral false spike; cuneate; unilateral; 0.3–0.5 cm long; bearing a triad of spikelets. Central inflorescence axis (3.5–)4–5 cm long; flattened; puberulous. 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; male; oblong; asymmetrical; dorsally compressed; 3.5–4.5 mm long; as long as fertile; deciduous with the fertile. Companion sterile spikelet glumes united below; coriaceous; 7 -veined; scabrous; ciliolate on margins; muticous. Companion sterile spikelet lemmas 1(–3); exserted from glumes; muticous.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets oblong; laterally compressed; 3.5–4.5 mm long; falling entire; deciduous with accessory branch structures.

GLUMES Glumes connate along margins below; shorter than spikelet. Lower glume oblong; asymmetrical; 3.5–4.5 mm long; 1 length of upper glume; coriaceous; pallid; 1-keeled; 7 -veined. Lower glume surface scabrous. Lower glume margins ciliolate. Lower glume apex lobed; 2 -fid; awned; 1 -awned. Lower glume awn 1 mm long. Upper glume oblong; asymmetrical; 3.5–4.5 mm long; 1 length of adjacent fertile lemma; coriaceous; pallid; 1-keeled; 7 -veined. Upper glume surface scabrous. Upper glume margins ciliolate. Upper glume apex lobed; 2 -fid; awned; 1 -awned. Upper glume awn 1 mm long.

FLORETS Fertile florets female. Fertile lemma ovate; laterally compressed; 3.5–4.5 mm long; cartilaginous; keeled; 3 -veined. Lemma apex caudate.

FLOWER Anthers 3; 2 mm long.

FRUIT Caryopsis 1.8–2 mm long. Embryo 1 length of caryopsis.

DISTRIBUTION North America: Mexico.

NOTES Cynodonteae. Reeder.

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