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.

Brachiaria arizonica

HABIT Annual; caespitose. Culms geniculately ascending, or decumbent; 15–60 cm long. Culm-nodes glabrous, or bearded. Lateral branches ample. Leaf-sheaths glabrous on surface, or hispid; with tubercle-based hairs. Ligule a ciliate membrane; 0.5–1 mm long. Leaf-blade base broadly rounded; asymmetrical. Leaf-blades lanceolate; 5–18 cm long; 3–10 mm wide. Leaf-blade surface glabrous, or hispid; sparsely hairy; hairy abaxially. Leaf-blade margins tuberculate-ciliate; hairy at base.

INFLORESCENCE Inflorescence composed of racemes. Peduncle pubescent above.

Racemes 4–6; borne along a central axis; unilateral; 1.5–3 cm long. Central inflorescence axis 7–15 cm long. Rhachis wingless; angular; pilose on surface. Spikelet packing adaxial; lax; irregular.

Spikelets solitary, or in pairs. Fertile spikelets pedicelled. Pedicels linear; 1 mm long.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; compressed slightly; acute; 3.3–4 mm long; falling entire. Spikelet callus square; incorporating lowest rhachilla internode with adnate lower glume; 0.3 mm long.

GLUMES Glumes dissimilar; reaching apex of florets; thinner than fertile lemma. Lower glume ovate; clasping; 0.25–0.5 length of spikelet; membranous; without keels; 5 -veined. Lower glume apex acute. Upper glume ovate; 1 length of spikelet; membranous; without keels; 5 -veined. Upper glume surface pubescent. Upper glume apex acute.

FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret similar to upper glume; ovate; 1 length of spikelet; membranous; 5 -veined; pubescent; acute. Fertile lemma elliptic; 3 mm long; indurate; without keel. Lemma surface rugulose. Lemma margins involute. Lemma apex apiculate. Palea involute; indurate; without keels. Palea surface rugose.

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

NOTES Paniceae. Gr Texas.

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