98 BULLETIN 1772, U. S. DEPARTMENT OF AGRICULTURE. 
Erect perennials, with flat blades and bristly, loosely flowered 
spikes. Species four, in temperate regions; one in the Himalayas, 
one in New Zealand, and two in the United States. 
Type species: Hlymus hystrix L. 
Asperella Humb., Magaz. Bot. Roem. and Usteri 7: 5, 1790, not Asprella 
Schreb., 1789, a typonym of Homalocenchrus Mieg. A single species, A. hystria, 
based on Hlymus hystria L. 
Hystrix Moench, Meth. Pl. 294. 1794. One species described, H. patula, 
based on Hlymus hystrix L. 
Gymnostichum Schreb., Beschr. Gris. 3: 127, pl. 47. 1810. One species de- 
scribed, G. hystrix, based on Hlymus hystria L. 
Our species are both woodland grasses, one, Hystrix patula Moench 
(HZ. hystrix (.) Millsp.) (Pl. X; fig. 49), in the Mississippi Valley 
and eastward; the other, 7. californica (Boland.) Kuntze, in western 
central California. They have little forage value, as they are no- 
where abundant. The first species mentioned, sometimes called 
bottle-brush grass, is worthy of cultivation for ornament. 
40. HorpEumM L. 
Spikelets 1-flowered, 3 (sometimes 2) together at each node of the 
articulate rachis (continuous in Hordeum vulgare), the back of 
the lemma turned from the rachis, the middle one sessile or sub- 
sessile, the lateral ones pediceled; rachilla disarticulating above the 
glumes and, in the central spikelet, prolonged behind the palea as a 
bristle and sometimes bearing a rudimentary floret; lateral spikelets 
usually imperfect, sometimes reduced to bristles; glumes narrow, often 
subulate and awned, rigid, standing in front of the spikelet; lemmas 
rounded on the back, 5-nerved, usually obscurely so, tapering into a 
usually long awn. 
Annual or perennial low or rather tall grasses, with flat blades and 
dense terminal cylindric-spikes. Species about 20, in the temperate 
regions of both hemispheres; 10 species in the United States, 3 being 
introduced from Europe. 
Type species: Hordeum vulgare L. 
Hordeum L., Sp. Pl. 84, 1753; Gen. Pl., ed. 5, 37. 1754. Linneeus describes 
six species, H. vulgare, H. hexastichon, H. distichon, H. zeocriton, H. murinun, 
and H. jubatum. The citation given in the Genera Plantarum is to Tourne- 
fort’s plate 295, which represents Hordeum vulgare. This species is therefore 
the type. All the Linnsean species are retained in the genus at present, but the 
first four are usually considered to be forms of one species. 
Zeocriton Beauy., Ess. Agrost. 114, pl. 21, f. 2. 1812. Ten species of 
Hordeum having staminate or sterile lateral spikelets are included ; H. distichum, 
the species figured, is taken as the type. 
Critesion Raf., Journ. de Phys. 89: 103. 1819. A single species is described, 
C. geniculatus Raf. This is Hordeum jubatum L. 
The most important species of the genus is Hordeum vulgare (fig. 
50), the cultivated barley. This is an annual, resembling bearded 
wheat, the awns as much as 6 inches long. In common or 4-rowed 
barley the 3 spikelets of each cluster are fertile, the lateral spikelets of 
