1918] 



The Grasses of Illinois 



281 



CO. Beach area north of Waiikogaii, Gates 2966; Waukegan, Gleason and Shoie 

 325. MACOUPIN CO. Carlinville, liohcrtson, Aug., 1880. Marshall co. Near 

 Lawn Eidge, V. H. Chase 1591. peoria co. Peoria, McDonald; Peoria, Brendel. 

 ST. CLAIR CO. Maseoiitah, U'clxvh. vermilion co. Miuu-io, Moshcr, Oct., 1915. 

 WABASH CO. Without locality, Schneek, Oct., 1900; without locality, Shearer; Old 

 Palmyra, Schnedk, Sept., 1879. will co. Joliet, A. H. Slceels, Sept., 1904. Win- 

 nebago CO. Fountaindale, M. S. Bebh. 



5. HOLCUS L. 



These grasses belong to tropical and warm temperate climates and 

 are natives of the Old World. The various cultivated sorghums belong 

 to this genus, also kaffir corn and broom corn. One species, H. 

 Jialapensis, is naturalized in America and has been found as a weed in 

 Illinois. The inflorescence consists of a large open panicle, the pedi- 

 eeled spikelets staminate. 



Holcus halapensis L. 



Johnson Grass (Fig. 28) 



Sorghum halapense, Gray 's Manual, 7th ed., Britton '07. 



Culms 3 to 5. feet tall, usually smooth; leaves 

 almost smooth, somewhat rough on the margins; 

 ligule membranous, 2 mm. long, the upper half 

 fringed ; spikelets in twos or threes ; perfect spike- 

 lets about 5 mm. long, with appressed hairs, awn 

 10 to 16 mm. long; pediceled spikelets slightly 

 longer than the sessile. 



This grass is perennial by long, stout, creeping 

 rootstocks and is very difficult to eradicate where 

 it once becomes established. It is much liked by 

 stock, but under certain conditions is poisonous 

 thru the production of hydrocyanic acid. 



TJrbana, Mosher, Oct., 1914. Experiment Station grounds, 

 Clinton, Oct., 1897. christian co. Taylorville, Andrews, Aug., 1898. cook co. 

 Glencoe, Gates 1686.2. wabash co. Without locality, Shearer; Mt. Carmel, 

 Schneckj July, 1894. 



6. SYNTHERISMA Walt. 

 Finger Grass. Crab Grass 



Our species of this genus are annuals. One species, Syntlierisma 

 filiformis, appears to be a native of Illinois ; the other two species are 

 known to have been introduced within the last century. The inflores- 

 cence consists of digitate, spike-like racemes, hence the common name, 

 finger grass. The spikelets are arranged in groups of two or three, one 

 subsessile or on a' very short pedicel, the others on pedicels as long as 

 the spikelets or longer. The leaves are usually thin and lax, the 

 ligules short and mem])ranous. 



28 



Fig. 28.— H. hal- 

 apensis, group of 

 spikelets 



champaign CO. 



