96 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 
appendages of the long central awn, sometimes equal, the glume being 
bifid; lemmas firm, convex on the back, nearly terete, the apex 
slightly 2-toothed, 5-nerved, the nerves obscure, the central nerve 
extending into a long, slender, finally spreading awn, sometimes one 
or more of the lateral nerves also extending into short awns; palea 
firm, nearly as long as the body of the lemma, the two keels serrulate. 
Low or rather tall cespitose perennials, with bristly spikes. Spe- 
cies about six, in the dry regions of the western United States. 
Type species: Sitanion elymoides Raf. 
Sitanion Raf., Journ. de Phys. 89: 103. 1819. One species is described, which 
is the same as Aegilops hystrix Nutt. 
Polyanthrix Nees, Ann. Nat. Hist. ser. 1. 1: 284. 1838. A single species 
based on Aegilops hystrix Nutt., which is Sitanion hystrix (Nutt.) J. G. Smith. 
This genus is closely related to Elymus, and until recent years has 
been almost universally included in it. The characters which sepa- 
rate Sitanion are the disarticulating rachis, together with the slender 
glumes and long-awned lemmas. 
There are three groups of species. Sitanion planifolium J. G. 
Smith and its allies have lanceolate rather than setaceous glumes, 
‘which are usually 1-awned or occasionally 2-awned. The awns are 
less spreading and the rachis disarticulates rather tardily. These 
species are found from California to Washington. 
A second series, including Sitanion jubatum J. G. Smith and its 
allies, has glumes cleft nearly to the base into three to several 
setaceous lobes. These species also are confined to the Pacific Coast 
States. 
The third series includes Nuttall’s original species, Sttanion hys- 
tria (Nutt.) J. G. Smith (fig. 48) and several allied species, found 
from the Great Plains to the Pacific coast. In some, the glumes are 
setaceous and entire; in others, some of the glumes are cleft into 
two equal, or usually unequal, awned lobes. ; 
The species of the three groups differ among themselves by only 
slight characters, and each group may represent several closely allied 
species or a single species with several forms or varieties. 
When young all the species furnish forage, but at maturity the dis- 
articulated joints of the spike, with their pointed rachis joints and 
long-awned spikelets, are blown about by the wind and often cause 
injury to stock, penetrating the nose and ears, working in by means 
of the forwardly roughened awns, and causing inflammation. The 
species are generally known as squirreltail or foxtail grasses. 
For a revision of the genus, see Smith, U. S. Dept. Agr., Div. 
Agrost. Bull. 18. 1899. 
39. Hystrix Moench. 
Spikelets 2 to 4 flowered, sessile, 1 to 3 at each node of a 
continuous flattened rachis, horizontally spreading at maturity; 
