THE GRASSES OF BRITISH HONDURAS AND THE PETEN, GUATEMALA 155

 17. CHLORIS Swartz
 Lemmas awnless, dark brown__ ...............--... ._ --_..................I.. C. petraea
 Lemmas awned, pale or light brown ...-....-----...- ___-_--_-.. ......- ....--.2. C. ciliata

 1. Chloris petraa Swartz, Prodr. Veg. Ind. Occ. 25. 1788.
 Perennial; culms distinctly flattened, glaucous, sparingly branched,
 sometimes stoloniferous, 0.5 to nearly 1 m. tall; blades flat or conduplicate,
 5 to 15 cm. long, 3 to 5 mm. wide, glabrous; spikes 3 to 7, suberect, 6 to
 10 cm. long; first glume notched, short awned. Open sandy land near the
 sea, southern United States and the West Indies to Panama.
 BnITISH HONDURAS. Stann Creek District: South Water Cay, Sampson 26.

2. Chloris ciliata Swartz, Prodr. Veg. Ind. Occ. 25. 1788.
 Perennial; culms densely tufted, erect, 40 to 60 cm. tall; blades flat,
 attenuate, involute pointed, the margins scabrous; spikes 3 to 5, ascending,
flexuous, 4 to 7 cm. long; spikelets about 2.5 mm. long, the glumes entire,
acute, the rudimentary floret inflated, saccate; lemma light brown, the
margins conspicuously silky ciliate; awn 1 mm. long. Wet open ground,
Texas and the West Indies to British Honduras. Also in Colombia.
 BRITISH HONDURAS. Corozal District: Corozal, Sampson 38. Belize
District: Gracie Rock, Gentle 1643.

 18. BOUTELOUA Lag.
1. Bouteloua triaena (Spreng.) Scribn. Proc. Acad. Phila. 307. 1891.
 Perennial; culms very slender, branching, widely spreading; spikes
numerous, usually second on the elongated axis, composed of a single spike-
let, the rachis sometimes produced beyond the spikelet; spikelets 1-flowered
with a 3-awned rudiment, the awns about 1 cm. long; first glume about
half as long as the second. Open ground and roadsides, southern Mexico
and Guatemala.
 GUATEMALA. Pet6n: Tayasal, Lake Pet6n, Lundell 3860.

 19. PENTARRHAPHIS H.B.K.
1. Pentarrhaphis scabra H.B-K. Nov. Gen. & Sp. 1: 178. pl. 60. 1816.
 Perennial; culms slender, densely tufted, erect, sometimes geniculate
below, 10 to 30 cm. tall; basal blades flat or involute, 3 to 5 cm. long,
not more than 1 mm. wide, more or less flexuous, those of the culms about
1 cm. long; spikes mostly 8 to 12 in terminal and axillary racemes,
the spikes 6 to 8 mm. long including the awns, composed of one
2-flowered spikelet and a group of 5 bristles below it, two of these being
the bifid continuation of the rachis, two a rudimentary spikelet, and one
the first glume of the perfect spikelet. Rocky ground, Mexico to Colombia.
 GUATEMALA. Pet6n: Sabana Zis, in shallow soil on outcropping limestone,
Lundell 3196.

 20. ORYZA L.
Plants annual; spikelets usually awnless or nearly so ..-. ....._----_ 1. 0. sativa
Plants perennial; spikelets awned.
 Spikelets 9 mm. long; awns 2 to 3 cm. long; glumes acuminate -.. ... 2. 0. alta
 Spikelets 5 mm. long; awns 1 to 2 cm. long; glumes acute_-... .. 3. 0. latifolia