Part 2, 1912] POACEAE 135 
31. HILARIA H.B.K. Nov. Gen. & Sp. 1: 115. 1815. 
Hexzxarrhena J. Presi, in Presl, Rel. Haenk. 1: 326. 1830. 
Scleropelia (Schleropelta] Buckl. Prel. Rep. Geol. & Agr. Surv. Tex. App. 1. 1866. 
Perennial grasses with long runners or stolons, the internodes arched, and the empty 
scales on each side of the spikelet-cluster united at the base, the flowering scale of the central 
spikelet abruptly narrowed into a 3-nerved beak. Spikelets in sessile deciduous clusters of 3, 
the empty scales resembling an involucre, the 3 on each side united at the base, the central 
spikelet 1-flowered, pistillate, the lateral spikelets 2-4-flowered, staminate. Empty scales 
much firmer than the flowering scales; anterior scales (those of the lateral spikelets) markedly 
inequilateral, the one side thin-membranous, nerveless, the outer side much firmer and broader, 
strongly nerved, the nerves vanishing below the apex or often extended as points or awns, the 
second scale of each spikelet broader and longer than the other one; posterior scales (those of 
the central spikelet) chartaceo-coriaceous, 2- or 3-lobed or 2- or 3-awned at the apex. Flowering 
scales of the lateral spikelet thin-membranous, 3-nerved, the lateral nerves fainter, the palets 
about as long; flowering scale of the central spikelet firmer, elliptic or oval below and nerveless 
or faintly nerved, abruptly narrowed into a long linear strongly 3-nerved beak, the palet about 
as long and similar in texture. 
Type species, Hilaria cenchroides H.B.K. 
Anterior empty scales of the spikelet-cluster, at least the narrower ones, and the posterior empty 
scales awned, the awns terete, hispidulous. 
Spikelet-clusters broad, sometimes nearly as wide as long, the awns usually 
shorter than the spikelets; first empty scale of the lateral spikelets with 
the lateral nerves, in addition to the midnerve, usually excurrent; second 
empty scale broad, one half as wide as long or more. 1. A. cenchroides, 
Spikelet-clusters narrow, the awns equaling or exceeding the spikelets; first 
empty scale of the lateral spikelets with the lateral nerves vanishing at or 
below the apex, the midnerve only excurrent; second empty scale nar- 
row, usually one third as broad as long or less. 2. H. Belangeri. 
Anterior empty scales of the spikelet-cluster awnless, the awns of the posterior .. 
empty scales flat, stout, strongly long-ciliate. 3. HY, ciliata. 
1. Hilaria cenchroides H.B.K. Nov. Gen. & Sp. 1: 117. 1815. 
Anthephora punctulata Steud. Syn. Gram. 111. 1854. 
Stems 6-30 cm. tall, glabrous, or often puberulent or hirsute below the inflorescence, 
simple or sparingly branched, often rooting at the lower nodes, the nodes barbed; leaf-sheaths 
glabrous or sparingly hirsute; blades commonly 3-6 cm. long, or rarely 1 dm. or more, up 
to 5 mm. wide, usually glabrous except for a few long hairs on the upper surface near 
the base, rarely sparingly hirsute all over; inflorescence 1.5-3 cm. long; spikelet-clusters 
5-6 mm. long, broadly cuneate, often nearly as broad as long; empty scales of the lateral 
spikelets strongly scabrous, shorter than the cluster, the first scale unequally 2-lobed at the 
apex, the midnerve running out between the lobes as a hispidulous awn, the lateral nerves also. 
often running out into short points, the second scale about one half as broad as long when 
spread out, 2-toothed or 2-lobed at the apex, 4-6-nerved, the midnerve sometimes excurrent 
as a short point, the lateral nerves usually vanishing at or below the apex, rarely excurrent; 
empty scales of the central spikelet 2-lobed to the middle, the hispid terete awn arising between 
the lobes, the inner margin of the lobes usually bordered with a hispid nerve which is commonly 
excurrent in a short point, the lobes obtuse or oblique. 
TYPE LOCALITY: On mountain plains, between Celaya and Guanajuato, Guanajuato. 
DISTRIBUTION : Southern Durango and San Luis Potosi to Guatemala. 
ILLUSTRATION : H.B.K. Nov. Gen. & Sp. i. 37. 
2. Hilaria Belangeri (Steud.) Nash. 
Anthephora Belangeri Steud. Syn. Gram. 111. 1854. 
Scleropelia stolonifera Buckl. Prel. Rep. Geol. & Agr. Surv. Tex. App. 1. 1866. 
Hilaria cenchroides texana Vasey, Contr. U. S. Nat. Herb. 1: 53. 1890. 
Hilaria texana Nash, in Small, Fl. SE. U. S. 68. 1903. 
Stems up to 3 dm. tall, simple, often puberulent just below the inflorescence, the nodes 
barbed; leaf-sheaths glabrous or sparingly hirsute; blades commonly 2-6 cm. long, rarely 
exceeding 1 dm., 1-2.5 mm. wide, usually rough, glabrous or sparingly hirsute; inflorescence 
