Lasiacis

Plants perennial (rarely annual); cespitose. Culms 0.5-8 m, weakly lignified, erect, arching, climbing, or decumbent, rooting at the nodes. Sheaths open; ligules membranous, sometimes ciliate; pseudopetioles sometimes present; blades linear to ovate, bases slightly to strongly asymmetric. Inflorescences open or contracted panicles, rachises usually visible, even distally, spikelets attached obliquely to the pedicels; disarticulation below the glumes. Spikelets subglobose to globose, with 2 florets. Glumes membranous, apices lanate pubescent, abruptly apiculate; lower glumes 1/3 – 2/3 as long as the spikelets, 5-13-veined, bases saccate, margins overlapping; upper glumes about as long as the upper florets, not saccate, 7-15-veined; lower florets sterile or staminate; lower lemmas membranous, apices lanate pubescent, abruptly apiculate; lower paleas present, sometimes reduced; upper florets stipitate, bisexual, appearing to be mucronate or acuminate; upper lemmas indurate, usually broadly elliptic to obovate, margins enclosing the edges of the paleas, apices obtuse, somewhat woolly pubescent, usually dark brown at maturity; upper paleas similar to the lemmas, but saccate below and gibbous above. Caryopses plano-convex, ovoid, or nearly orbicular; embryo about M as long as the caryopses; hila oblong to nearly round, x = 9.

Distribution

Puerto Rico, Virgin Islands, Fla.

Discussion

In Lasiacis the upper florets appear to be mucronate or acuminate. The mucro or acuminate apex is formed by the tuft of hairs at the apex of the upper floret.

Lasiacis is a neotropical genus of 16 species that extends from southern Florida to Peru and Argentina. Two species are native to the Flora region. The shiny black color of its mature florets and the oil-filled cells of the inner epidermes of the glumes and sterile lemmas distinguish Lasiacis from all other grasses. Birds are a common dispersal agent.

Selected References

Davidse, G. and E. Morton. 1973. Bird-mediated fruit dispersal in the tropical grass genus Lasiacis (Gramineae: Paniceae). Biotropica 5:162-167.

Davidse, G. 1978. A systematic study of the genus Lasiacis (Gramineae: Paniceae). Ann. Missouri Bot. Gard. 65:1133-1254

Lower Taxa

Lasiacis divaricata, Lasiacis ruscifolia

Key

1	Leaf blades linear-lanceolate to narrowly lanceolate, 3-16 cm long, 3-30 mm wide	Lasiacis divaricata
1	Leaf blades ovate to broadly lanceolate, 2-16 cm long, 8-56 mm wide	Lasiacis ruscifolia