7G STUDIES IN THE VEGETATION OF THE STATE 



years' duration, joining the above meadow formation. The 

 same is likewise true for V. hastata and Vernonia gigantea, 

 all three of which possess a bitter juice, rendering them dis- 

 tasteful to stock. Polygala vertioillaia is a frequent, but 

 sparse, inconspicuous annual of low prairies and meadows. 

 It adds nothing to the floral covering nor to the aspect. 

 Buellia ciliosa is a low, hairy perennial occurring sparsely at 

 a few stations in low prairies, where it aggregates in loose 

 patches. The beautiful lilac-colored flowers are ephemeral, 

 opening during the night and falling away by 12 :00 M. They 

 scarcely contribute to the floral aspect on account of the 

 taller fades. Flowers of Buellia ciliosa are funnel-form, 

 with a long tube, at the base of which is secreted the nectar. 

 The period of anthesis lasts for sixty days. Psoralea argo- 

 phylla is a low, branching perennial of moist prairies, where 

 it assumes a gregarious habit. Its characteristic white stems 

 and leaves render patches of this plant conspicuous objects 

 of the aspect. On high prairies it is usually loosely inter- 

 spersed throughout and hence never noticeable. The small, 

 blue flowers do not add to the plant. After maturation, the 

 plant becomes freed from the caudex and rolls about on the 

 prairies as a tumble-weed. Psoralea tenuiflora is found at a 

 few stations in low prairies and meadows. It is a rather 

 tall, diffusely branched perennial, conspicuous on account 

 of its many small spikes of blue flow^ers, which continue for a 

 month or more. 



Asclepias verticillata occurs as a subcopious plant through- 

 out low prairies and meadows. Its individuals are hardly 

 distinguishable from the facies until the small umbels of 

 white flowers appear. The small milkweed is perennial. 

 Maturation begins during the latter part of August, at which 

 time the follicles burst, setting free the comose seeds. Ascle- 

 pias tuberosa is a rare plant in the low prairies. Its mostly 

 clustered stems proceed from thickened perennial roots and 

 terminate with conspicuous, orange-red umbels which are 

 among the brightest objeci . of the aspect. It is to be noted 



