WIS] The Grasses of Illinois 275 



DESCRIPTIONS AND DISTRIBUTION OF ILLINOIS GRASSES 



1. TRIPSACUM L. 



This is a subtropical genus of which one species is found in southern 

 Illinois. It includes tall, coarse perennials with creeping rootstocks. 

 The inflorescence consists of solitary or clustered spikes borne at the 

 ends of the culms or their branches. There are two kinds of spikelets 

 in each spike, the pistillate spikelets borne singly, sunken in the thick- 

 ened axis of the lower part, and the staminate in pairs on the slender 

 upper part. The lower part of the axis is very hard and woody, and 

 separates readily into joints. In each of these joints is embedded a 

 pistillate spikelet, which has a very hard outer glume. The upper part 

 of the stalk is slender, not woody, and does not separate into joints, 

 but falls off entire. 



Tripsacum dactyloides L. 

 Gama Grass. Sesame Grass (Fig. 17) 



Michaux '03, 60; Lapham '57, 548, 598; Patterson '76, 52; Flagg '78, 284; 

 Brendel '87, 89. 



Entire plant smooth and glabrous; culms 3 to 7 feet tall; leaves 

 3 dm. or more long, -1 to 3.5 cm. wide ; ligule a fringe of hairs less than 

 1 mm. long ; spikelets 8 mm. long. 



This is one of the largest grasses found in the state. It prefers 

 moist soil in swamps or along ditches and streams. It is an excellent 

 forage grass. 



ILLINOIS SPECIMENS: Withouf locality, southern Illinois, Vasey. christian 

 CO., Taylorville, Andrews, hancock co. Without locality. Mead in 1843. Ma- 

 coupin CO. Macoupin, Fobertson, July, 1884. marion co. Without locality, M. S. 

 Bebb, 1860. ST. claib co. Mascoutah, Welsch. wabasii co. Without locality 

 Schnecl-, July, 1890; without locality, Shearer. 



2. ERIANTHUS Michx. 

 Wooly Beard Grass 



This genus is found in both temperate and tropical regions. The 

 plants are tall, reed-like perennial grasses with thick, creeping root- 

 stocks. One species is cultivated for ornament, and is commonly known 

 as plume grass, wool grass, or hardy pampas grass. The inflorescence 

 is a large, compact panicle clothed with long, silky hairs, which are 

 borne on the panicle branches and in a tuft at the base of each spikelet. 

 The spikelets are in pairs, one pedicele(i, the other sessile, but both 

 are perfect, of equal size, and bear long awns. 



Erianthus divaricatus (L.) Hitchc. 

 Spiral-awncd Plume Gi'ass (Figs. 18 and 19) 



Erianthus alopecuroides, Lapham '57, 548, 599 ; Patterson '76, 52 ; Flagg '78, 

 285. E. saccharoidcs, Brendel '87, 89. 



