LEGUMINOSAE 



PULSE FAMILY 



SHOWY TICK TREFOIL 



Desmodium canadense (L. ) DC. 



Of the dozen or more Tick Trefoils found in Illinois this is 

 the showiest. It grows in open woods and along streams and 

 railroads from Nova Scotia to Manitoba and south to North 

 Carolina and Oklahoma, and blooms from July 

 to September. It is perennial, with stout hairy 

 stems 2-8 feet high and bearing leaves which are 

 somewhat hairy below but smooth above. The 

 upper leaves are nearly sessile but the lower have 

 petioles up to i inch long. 



The large, purple or bluish purple, conspicu- 

 ous flowers are produced in a dense-branched 

 inflorescence. The calyx is somewhat 2-lipped, 

 with the upper lip 2-toothed and the lower 3- 

 lobed. The corolla is butterfly shaped; the stand- 

 ard and wings are oblong and the keel is nearly 

 straight. Nine of the 

 10 stamens are united. 



The pistil develops 

 into a pod which when 

 mature is nearly sessile 

 in the calyx, about i 

 inch long and 3-5-joint- 

 ed. Each triangular 

 joint contains i seed 

 and is covered with 

 hooked hairs that en- 

 able it to cling tena- 

 ciously to clothing or 

 to animals. 



The Hoary-leaved Tick Trefoil, Desmodium canesccns (L.) 

 DC, is another species quite common in Illinois, especially along 

 railroads. It grows 3-5 feet high and is densely clothed with 

 short, hooked hairs and also longer glutinous hairs that make 

 the plant somewhat sticky. The 3 leaflets are 1-+ inches long, 

 about equaling the petiole, and the terminal leaflet is usually 

 somewhat larger than the other 2. 



The Illinois Tick Trefoil, Desmodium illinoense Gray, is simi- 

 lar to the Showy Tick Trefoil but may be distinguished by its thick, 

 rigid leaves which are very strongly netted below, the large and 

 persistent stipules, and the 3-5 oval segments of the jointed pod. 



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