68 POACEAE 
fourth scale, enclosing a pistillate flower, small and hyaline and bearing a long rigid con- 
torted and geniculate awn ; palet small and hyaline, or wanting. Pedicellate spikelet awn- 
less, the outermost scale thinner than the corresponding one in the sessile spikelet. Sta- 
mens 3. Styles distinct. Stigmas plumose. 
Upper sheaths tuberculate along the keel and the first scale of the pedicellate 
spikelet on the midnerve, the latter 1.5 em. long or more and glabrous. 1. H. melanocarpus. 
Upper sheaths and the first scale of the pedicellate spikelet smooth all over, the 
latter 1 em. long or less, papillose-hispid toward the summit and near the 
margins. 2. H. contortus. 
1. Heteropogon melanocárpus (Muhl.) Ell. Annual. Stems 4-15 dm. tall, much 
branched above : upper leaf-sheaths at least tuberculate on the keel; blades 5 dm. long or 
less, 3-12 mm. wide: racemes 3-6 cm. long, exserted, or included at the base, the pedun- 
cles pilose with ascending hairs, the internodes between the upper spikelets densely pu- 
bescent with long chestnut-brown hairs: sessile spikelet 5-6 mm. long, the awn 9-15 cm. 
long ; pedicellate spikelet 15-22 mm. long, sterile or staminate, the first scale long-acumi- 
nate, tuberculate on the midnerve. [H. acuminatus Trin. ] 
In cultivated grounds, South Carolina to Florida, Texas, Arizona and Mexico. Also in tropical 
America. Summer and fall. 
2. Heteropogon contórtus (L.) Beauv. Perennial. Stems 2-8 dm. tall, rather 
sparingly branched above: leaf-sheaths smooth, even on the keel; blades 2 dm. long or 
less, 3-7 mm. wide: racemes 4-6 cm. long, exserted, or included at the base, the peduncles 
hispidulous, the internodes between the upper spikelets densely pubescent with long nearly 
appressed chestnut-brown hairs: sessile spikelet 5-6 mm. long, the awn 4.5-8 em. long ; 
pedicellate spikelet about 1 cm. long, sterile or staminate, the first scale acute, papillose- 
hispid toward the summit and near the margins with long hairs. 
In dry soil, southern and western Texas to Arizona and Mexico. Widely distributed in the warmer 
parts of all countries. Spring to fall. 
16. HILARIA H.B.K. 
Stoloniferous grasses, decumbent and branching at the base, with flat or convolute 
leaf-blades and spicate inflorescence. Spiklets in sessile deciduous crowded clusters of 3, 
the empty scales resembling an involucre, the central spikelet 1-flowered, the flower pistil- 
late or perfect, the lateral spikelets 2-flowered, the flowers staminate. Scales 4, the 2 outer 
empty, rigid, thin or indurated, the first the larger and varying much in shape, entire 
or 2-cleft at the toothed or lacerate apex, awnless, or bearing an awn between the lobes, 
the second scale narrower, often keeled, entire or 2-toothed at the apex, awnless, mucronate, 
or short-awned ; third and fourth scales thin-membranous, entire or toothed at the apex, 
each in the lateral spikelets enclosing a palet and a flower, in the central spikelet the third 
scale is empty. Stamens 3. Styles a little united at the base. Stigmas shortly plumose. 
Outer scales of the spikelet linear or oblong, the nerves parallel, some of them awned. 1. H. Texana. 
Outer scales of the spikelet cuneate, the nerves strongly diverging above, awnless. 2. H. mutica. 
1. Hilaria Texana (Vasey) Nash. Creeping by arched stolons. Stems 1-2.5 dm. 
tall: basal leaves numerous ; blades 1-5 cm. long and about 2 mm. wide, very rough, pu- 
bescent, the upper surface densely so with short hairs, the lower surface with a few lon 
es ee 2-3 cm. long, of 4-8 spikelets, which are 4-5.5 mm. long, each cluster nak 
at the base. 
On hills and plains, central Texas to Arizona. Spring and summer. CREEPING MESQUITE. 
2. Hilaria mütica (Buckl.) Benth. Stems rigid, 2-6 dm. tall, from rootstocks : leaf- 
blades erect, firm, 1 dm. long or less, 2-4 mm. wide: spike 4-6 cm. long: spikelets many, 
crowded, usually overlapping, 6-7 mm. long. 
On plains and prairies, Texasto Arizona. Alsoin Mexico. Summer and fall. BLACK GRAMA. 
17. NAZIA Adans. 
An annual grass, with flat leaf-blades and racemose or spike-like inflorescence. Spikelets 
articulated below the empty scales, 1-flowered, solitary, or in clusters of 3-5. Scales 2 or 3, 
the first small, or sometimes wanting, the second firm, with its nerves dorsally armed with 
hooked prickles, the third scale membranous, subtending a hyaline palet and a perfect 
flower. Stamens3. Styles short, distinct. Stigmas moderately long, plumose. 
1. Nazia alièna (Spreng.) Scribn. Tufted. Stems finally prostrate and rooting and 
branching at the lower nodes, 1-3 dm. tall: leaf-blades ciliate on the margin : spike 4-10 
cm. long: spikelets about 2.5 mm. long. 
On dry hillsides, Texas to Arizona. Also in Central and South America, and the West Indies. 
Spring and fall. 
