Aristida riparia

HABIT Perennial. Culms (60–)90–130(–180) cm long. Lateral branches lacking. Leaf-sheath oral hairs bearded. Ligule a fringe of hairs; 0.4–0.8 mm long. Collar glabrous. Leaf-blades straight, or curled (lower, very rarely); flat, or convolute (upper, rarely); 19–70 cm long; (2.8–)3–5 mm wide. Leaf-blade surface scabrous; rough on both sides; pilose (at base); densely hairy (lanose at base, adaxially); hairy adaxially. Leaf-blade apex acute; antrorsely scabrous.

INFLORESCENCE Inflorescence a panicle.

Panicle spiciform; 20–44 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; straight; 1–1.5 mm long; bearded; acute.

GLUMES Glumes persistent; dissimilar (lower longer than upper). Lower glume lanceolate; 12–22 mm long; 1 -veined. Lower glume primary vein scabrous. Lower glume surface scabrous; rough generally. Lower glume apex acute, or acuminate; awned. Upper glume lanceolate; 10–22 mm long; 1 -veined. Upper glume surface smooth. Upper glume apex entire; acute, or acuminate.

FLORETS Fertile lemma subterete; 6–8 mm long; without keel; rounded throughout; 3 -veined. Lemma surface smooth; without grooves. Lemma margins convolute. Lemma apex awned; 3 -awned. Principal lemma awn straight; ascending; simple at base; with (26–)32–64 mm long limb; with twisted column. Column of lemma awn (6–)14–24(–52) mm long (sometimes variation in the same inflorescence). Lateral lemma awns ascending; 22–42(–60) mm long; subequal to principal.

DISTRIBUTION South America: Mesoamericana, northern South America, 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.