364 A'N'lS'UAL REPORT. 



A. simplicifolius, Gray, and A. trifiorus, Grray. The former was 

 observed only in Montana, on the hills between McClennan and 

 Hodges stations on the Northern Pacific railroad. Psoralea 

 wgophijlla, Pursh, P. esculenfa, Pursh, and P. lanceolata, Pursh, 

 were noted. The latter possesses the peculiarity of forming at 

 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 albiis, L. (commonly 

 called "tumble-weed") on the prairies of Minnesota. Psoralea argo- 

 phijlla and escidenta also break off near the ground, but do not ap- 

 pear to form a distinct joint. The separation in these species is 

 effected by means of a constriction on the st^jm, which cuts off, as 

 it were, the nourishment from the root, and causes the stalk to 

 shrivel at that point, when the least touch or gust of wind releases 

 the plant. On the hills near Mandan, and in no other place along 

 the route, Petalostemon macrostacJtyus, Torr., was collected. Here 

 also P. villosus, Nutt., was quite abundant. Amorpha friiticosa, 

 L., and A. canescens, Nutt,, were both well represented, but a little 

 farther westward they were largely replaced by A. microjjhi/Ua^ 

 Pursh. Oxytropis^ Desmodium, Vicia, Lathy rus and Hosackia 

 were found in abundance throughout the territory. Lupinus 

 perennis, L., was met with in the valley of the Green river; also an 

 apparently undescribed species of this genus was collected. 



Eleven species of Potentilla were collected, among them 

 P. Pennsylvafiica^ L., and P. fruticosa, L., the latter nowhere 

 except in Pyramid Park. Only one species of Pruniis was seen 

 west of the Missouri river, namely, P. pumila, L. Growing 

 abundantly on the rocky buttes was Chamcerhodos erecta, Bunge. 

 So far as I kuow, this plant has not before been referred to this 

 region. Oar most common species of strawberry {Fragaria 

 Virginiana^ Duchesne) abounds east of the Missouri, but is very 

 infrequent farther west. The hot dry weather prevailing during 

 June and July doubtless proves unsuitable for its growth. 



A gooseberry {Rlhes) near R. Cynoshati, L., of a low bushy form, 

 thickly armed with long stout prickles, grows on the summit of 

 the dry baked clay hills of western Dakota and eastern Montana. 

 Although growing in these extremely dry localities, it was heavily 

 loaded in the month of July with large ripe juicy fruit, possessing 

 a sweet and agreeable taste. Aside from scattered patches of 

 Shepherdia, this was the only native edible wild fruit that was 

 observed along the route after crossing the Missouri. 



