ANDROPOGONE/E 



153 



Isciiaemum rugosum, Salisb. 



Thia is an erect annual grass with tufted, leafy, compressed 

 stems varying in length from 10 inches to 2 feet. 



The leaf-sheath is glabrous, loose and compressed, with a mem- 

 branous auricle confluent with the truncate ligule. Nodes usually 

 glabrous but sometimes also puberulous. 



The leaf-blade is narrow, linear-lanceolate, flat, base contracted, 

 flaccid, acuminate, rounded at the base, glabrous or sparsely hairy 

 on both the surfaces; the topmost leaf is often reduced to an 

 inflated sheath enclosing the inflorescence partially. 



The racemes are usually two, erect, fragile, I to 3 inches long 

 with a slight thickening of the peduncle below the inflorescence ; 

 the joints are Yz to % as long as the sessile spikelets ; trigonous 

 and subclavatc, and with long hairs on one side. The spikelets 

 are linear-oblong, glabrous or villous, % to %. inch long, sessile 

 and stalked spikelets close together ; the pedicel of the stalked 

 spikelet is thick about Y> or less than the length of the sessile spike- 

 let, ciliate on one side, confluent with the thick callus of the sessile 

 spikelet, which is sparsely bristly. The sessile spikelet consists of 



Fig. 13-.-- Jschremum rugosum. 



1. A part of the raceme showing sessile spikelets with reduced pedicelled spikelets ; 2. 



a sessile spikelet and a well developed pedicelled spikelet ; 3. a reduced pedicelled 



spikelet ; 4, 5, 6 and 8. the first, second, third and the fourth glume of the sessile 



spikelet ; 7 and 9. palea of the third and fourth glumes of the sessile spikelet : 10. ovary. 



four glumes and is awned. The first glume is concave, pale yellow, 

 shining and cartilaginous to about % its length from the base, and 

 the upper third is membranous, dimidiately ovate ; at the back in the 

 cartilaginous portion, there are three to six deep convex smooth 

 ridges running across the glume ; the membranous tip is thin and 

 with anastomosing green veins ; the margins of this glume are 

 thick, narrowly incurved, ciliolate, and with a narrow wing on the 

 outer margin. The second glume is oblong-lanceolate or lanceolate, 

 coriaceous, acuminate, scaberulous, keeled and laterally compressed 

 and on the keel just below the tip there is a narrow ciliate wing. 



