Aristida megapotamica

HABIT Perennial. Culms (37–)60–140 cm long. Lateral branches lacking. Leaf-sheath oral hairs lacking, or bearded. Ligule a fringe of hairs; 0.5–0.7 mm long. Collar glabrous. Leaf-blades curled (lower), or straight (upper); flat (lower), or convolute (upper); 20–50 cm long; 3–5 mm wide. Leaf-blade surface scabrous; rough on both sides, or adaxially; glabrous, or pilose; hairless throughout, or except near base; moderately hairy; hairy adaxially. Leaf-blade apex acute; antrorsely scabrous.

INFLORESCENCE Inflorescence a panicle.

Panicle spiciform; 11–35(–40) cm long.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets subterete; breaking up at maturity; disarticulating below each fertile floret. Floret callus elongated; curved; 1–1.8(–2.5) mm long; bearded; acute.

GLUMES Glumes persistent; dissimilar (lower longer than upper). Lower glume lanceolate; (16–)20–33 mm long; 1 -veined. Lower glume primary vein scabrous. Lower glume surface scabrous; rough generally. Lower glume apex setaceously attenuate; awned. Upper glume lanceolate; 14 mm long, or 6–28 mm long; 1 -veined. Upper glume surface smooth. Upper glume apex entire; setaceously attenuate; awned.

FLORETS Fertile lemma subterete; (6–)8–12 mm long; without keel; rounded throughout; 3 -veined. Lemma surface scabrous, or scaberulous (rarely); rough above (upper 2/3); without grooves. Lemma margins convolute. Lemma apex awned; 3 -awned. Principal lemma awn straight, or flexuous; twisted together, or ascending; simple at base; with 25–55 mm long limb; with twisted column. Column of lemma awn (20–)25–60(–95) mm long. Lateral lemma awns ascending, or wrapped around principal; 22–48 mm long; shorter than principal.

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

NOTES Aristideae. Lo-W 1993.

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