Thrasya petrosa

HABIT Perennial; caespitose. Culms 100–150 cm long; 2–3 mm diam. Culm-internodes hollow. Culm-nodes pubescent. Ligule an eciliate membrane; 0.5–1 mm long. Leaf-blades flat, or revolute; 4–6 mm wide.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 1; single; arcuate; unilateral; 12–28 cm long. Rhachis broadly winged; folded longitudinally to embrace spikelets; 4–5 mm wide; terminating in a barren extension; extension flattened. Spikelet packing alternately adaxial and abaxial; regular; 1 -rowed.

Spikelets pectinate; in pairs. Fertile spikelets sessile and pedicelled; 2 in the cluster. Pedicels fused to internode; united wholly.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; 4.5–5.5 mm long; falling entire. Spikelet callus square; 0.5 mm long; pubescent.

GLUMES Glumes dissimilar; reaching apex of florets; thinner than fertile lemma. Lower glume oblate; 0.5–1.5 mm long; 0.1–0.3 length of spikelet; hyaline; without keels; 0–1 -veined. Lower glume lateral veins absent. Lower glume apex obtuse. Upper glume elliptic; 1 length of spikelet; membranous; without keels; 5 -veined. Upper glume surface pilose. Upper glume apex acute.

FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret elliptic; 1 length of spikelet; coriaceous; 4 -veined; sulcate and readily splitting into two halves; pilose; acute. Palea of lower sterile floret becoming indurate on flanks at maturity. Fertile lemma elliptic; 3.5–4 mm long; coriaceous; without keel; 5 -veined. Lemma margins involute. Lemma apex acute; pubescent. Palea coriaceous.

FLOWER Lodicules 2; fleshy; truncate. Anthers 3; 1.8–2.2 mm long.

DISTRIBUTION South America: Mesoamericana, northern South America, western South America, Brazil, and southern South America.

NOTES Paniceae. Pohl.

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