51 



the center, straight, barel)^ exceeding- the dead culms with their spht 

 and curled leaves. The culms and especially the spikelets are red in 

 color and give a reddish tone to the whole bunch. 



This species forms one of the most distinctive bunches of the 

 association, due to the depressed or prostrate radiating culms with 

 their erect or almost appressed leaves, and to the persistence on the 

 dead culms of the recurved leaves of the previous season. The culms 

 extend beyond the leaves, and bear small, but conspicuous, panicles of 

 red spikelets. This species is more characteristic of the association to 

 which it gives its name, but is also frequent in the typical bunch-grass, 

 where its peculiar habit makes it conspicuous. 



5. Bouteloiia hirsuta. — Bunches low, irregular, two to four inches 

 (5-10 cm.) high, usually confluent in matlike masses 5-12 inches 

 (1-3 dm.) in diameter; leaves short, irregular in position, forming 

 a loose tuft, conspicuously gray-pubescent, and giving a gray color to 

 the whole bunch. The slender culms, 4-12 inches (1-3 dm.) high, 

 appear during the late aestival season. The small bunches are entirely 

 too low to compete with the other grasses for space or to constitute 

 a conspicuous element in the association. They are usually restricted 

 to the intervening spaces, where they have the general habit of mats 

 rather than of bunches. They associate frequently with SclagincUa 

 rupestris. 



6. Boutcloua curtipcndula. — Bunches loose, 6-12 inches (1-3 dm.) 

 in diameter, eight to ten inches (2-3 dm.) high; leaves mostly all 

 erect, six to eight inches (15-20 cm.) long. 



7. Cyperns Schzvcinitzii. — Bunches very open and loose, basal 

 leaves few in number, ascending; culms several, erect or ascending. 

 The plant frequently has the habit of an interstitial rather than of a 

 bunch-grass. 



8. Andropogon scopariiis. — Bunches one to three feet (3-8 dm.) 

 wide, circular, 1-1.5 feet (3-4 dm.) high, compact, and regular; 

 leaves very long and narrow, erect or ascending, the dead leaves 

 persisting as a dense mass at the base, or recurved around the margin 

 of the bunch; culms about two feet (6 dm.) high, the dead culms 

 l^ersisting through the following summer. 



The bunches are notable for their large size and the dense mass 

 of dead leaves ming^led with the living- ones. As the bunches grow 

 older the center dies, and ring's are formed which reach a maximum 

 diameter of over a yard (i m.). In such rings the zone of living 

 grass is three to eight inches (1-2 dm.) wide, and the central portion 

 is elevated four to six inches (10-15 cm.) above the g-eneral level. 

 It is composed of a dense mass of old roots and culms mingled with 



