Brachiaria olivacea

HABIT Annual; caespitose. Culms geniculately ascending; 60–100 cm long; rooting from lower nodes. Culm-internodes (3–)5–9(–10) cm long; distally glabrous. Culm-nodes glabrous. Lateral branches sparse. Leaf-sheaths glabrous on surface; outer margin hairy. Leaf-sheath oral hairs ciliate. Ligule a ciliate membrane; 0.7–0.9 mm long. Leaf-blade base cordate. Leaf-blades lanceolate; (4.5–)5–20 cm long; 6–16(–20) mm wide. Leaf-blade surface glabrous. Leaf-blade margins scabrous. Leaf-blade apex attenuate.

INFLORESCENCE Inflorescence composed of racemes; terminal and axillary; embraced at base by subtending leaf. Peduncle 9–18 cm long.

Racemes (6–)7–14; borne along a central axis; unilateral; (3–)5.5–9 cm long. Central inflorescence axis 8–18 cm long. Rhachis wingless; angular; 1–1.2 mm wide. Spikelet packing contiguous; irregular; 2 -rowed.

Spikelets solitary, or in pairs. Fertile spikelets sessile, or sessile and pedicelled. Pedicels linear; 1–2 mm long; scabrous; tip cupuliform.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; compressed slightly; turgidly plano-convex; acute; 4.5–4.9 mm long; 2.1–2.3 mm wide; falling entire.

GLUMES Glumes dissimilar; reaching apex of florets; thinner than fertile lemma. Lower glume ovate; clasping; 1.5–1.8 mm long; 0.33 length of spikelet; membranous; without keels; 5–7 -veined. Lower glume lateral veins convergent at apex. Lower glume apex truncate. Upper glume elliptic; 4.2–4.7 mm long; 1 length of spikelet; membranous; dark green (olive); without keels; 9 -veined. Upper glume primary vein conspicuous. Upper glume lateral veins with cross-veins. Upper glume surface glabrous. Upper glume apex acute.

FLORETS Basal sterile florets barren; with palea. Lemma of lower sterile floret similar to upper glume; ovate; 4.1–4.5 mm long; 1 length of spikelet; membranous; 5 -veined; glabrous; acute. Palea of lower sterile floret 1 length of lemma. Fertile lemma elliptic; 3–3.2 mm long; 1.8–2 mm wide; indurate; yellow, or light brown; without keel. Lemma surface rugose; with distinct germination flap. Lemma margins involute. Lemma apex apiculate. Palea involute; indurate; without keels. Palea surface rugose.

FLOWER Anthers 3; 1–1.2 mm long.

FRUIT Caryopsis with adherent pericarp; ellipsoid; 2.3–2.8 mm long. Embryo 0.66 length of caryopsis. Hilum elliptic, or linear; 0.25 length of caryopsis.

DISTRIBUTION North America: Mexico.

NOTES Paniceae. Sanchez-Ken 2012.

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