106 BOTANICAL GAZETTE. 
maturity a perfect joint on the stem near the ground. A light 
wind will then cause the plant to break off and go rolling along 
in the same manner as happens with Amarantus albus, L. (com- 
monly called “tumble-weed”’), on the prairies of Minne 
Psoralea argophylla and esculenta also break off aear the ground, 
but do not appear to form a distinct joint. The separation in i 
species is effected by means of a constriction on the stem, vi 
cuts off, as it were, the nourishment from the root, and causes t F 
stock to shrivel at that point, when the least touch or gust 0 
wind releases the plant. On the hills near Mandan, and in n0 
other place along the route, Petalostemon macrostachyus, Tort., 
was collected. ere also P. villosus, Nutt., was quite abundant. 
A d 
was collected. 
even species of Potentilla were collected, among them P- 
Pennsylvanica, L., and P. fruticosa, L., the latter nowhere eX- 
region. Our most common species of strawberry (Fragaria Vir- 
giniana, Duchesne) abounds east of the Missouri, but is very in- 
frequent farther west. The hot dry weather prevailing during 
June and July doubtless proves unsuitable for its growth. 
A gooseberry (Ribes) near R. Cynosbati, L., of a low bushy 
it was heavily loaded in the month of July with large ripe juicy 
fruit, possessing a sweet and agreeable taste. Aside from scat- 
uit, é 
tered patches of Shepherdia, this was the only native edible wil 
fruit that was ob 
souri 
Hippuris vulgaris, L., rare in Minnesota, is plentiful in every 
little stream west of the Missouri, provided it is not alkaline and 
contains water sufficient to prevent complete evaporation during 
the dry season, 
Of the Onagraceee, Epilobium palustre, L., and E. molle, Torts» 
