132 PULSE FAMILY. 



30. DESMODIUM, TICK TREFOIL. (Greek : a band or chain, from 

 the connected joints of the pod.) 11 Flowers in summer. 



1. Native hardy species ; the joints of the pod adhere to clothing or to 

 the coats of animals; flowers sometimes turning greenish in withering. 



* Pod raised far above the calyx on a slender stalk, straightish on the 

 upper margin, divided from below into 1-4 joints ; flowers in one naked 

 terminal raceme or panicle ; plants smooth, l-3 high ; stipules bristle- 

 form. 



D. nudif!6rum, DC. The mostly leafless flower-stalk and the leaf- 

 bearing stem rising separately from a common root; the leaves all 

 crowded on the summit of the stem ; leaflets broadly ovate, bluntish, 

 pale beneath. Common. 



D. acuminatum, DC. Flower stalk terminating the stem, which bears 

 a cluster of leaves ; leaflets large (4'-5' long), round-ovate, with a taper- 

 ing point, or the end one blunter, green both sides. Common. 



D. paucifl6rum, DC. Leaves scattered along the low, (8'-15' high) 

 ascending stems ; leaflets rhombic-ovate, pale beneath ; raceme terminal, 

 few-flowered. Ont. to Penn., Kans. and S. 



* * Pod raised on a stalk little if at all surpassing the deeply-cleft calyx ; 

 stems long, prostrate or decumbent; racemes mostly simple, axillary 

 and terminal ; stipules ovate, striate, taper-pointed, persistent. 



D. rotundii61ium, DC. Soft-hairy; leaflets orbicular, about 3 f long ; 

 flowers purple, the 3-5 rhombic-oval joints of the pod rather large. 



* * * Pod little if at all stalked in the calyx ; racemes panicled. 



- Stems erect, 3-6 high ; stipules large, ovate or lance-ovate, and 

 pointed ; bracts similar but deciduous; flowers large for the genus. 



w- Pods of 4-7 rhombic-oblong joints, each joint about V long. 



D. can^scens, DC. Hairy ; stems branching ; leaves pale ; leaflets 

 ovate, bluntish, about the length of the common petiole, reticulated 

 beneath and both sides roughish with fine, close pubescence; joints of 

 pod very adhesive. Common. 



D. cuspidatum, Torr. & Gray. Very smooth, except panicle ; stem 

 straight; leaflets lance-ovate, taper-pointed (3'-5' long), longer than the 

 common petiole ; pod with smoothish joints. Common. 



*+ ++ Pods of 3-5 oval joints, not over \' long. 



D. Illino^nse, Gray. Rough with short hairs ; leaflets ovate-oblong 

 or ovate-lanceolate (2'-4' long), obtuse, firm, venation prominent, whitish 

 beneath ; pod scarcely over 1' long. 



t- H- Stems erect, 2-6 high ; stipules mostly deciduous, awl-shaped, 

 small, and inconspicuous ; racemes panicled. 



w Bracts small and inconspicuous; common petiole slender; flowers 

 smallish ; joints of pod 3-5, unequal-sided. 



D. viridifl6mm, Beck. Stem very downy ; leaflets broad ovate, very 

 blunt, white, with soft-velvety down beneath. N. J. to Fla., Mo., 

 and Tex. 



D. Dillfcnii, Darl. Stem and the oblong or oblong-ovate, bluntish, thin 

 leaflets softly and finely pubescent ; the latter 2'-3' long. Common. 



D. paniculatum, DC. Smooth, or nearly so, throughout ; leaflets 

 lanceolate or lance-oblong, tapering to a blunt point, 3'-5' long ; panicle 

 loose. Common. 



