192 
ON THE GEOLOGY AND NATURAL HISTORY 
Oenothera biennis , Linn. Common along the valley of the Missouri to the mountains. 
Oenothera rhombipetala , Nutt. Sand hills, August 4th. 
Oenothera lavandulaefolia , Torr. and Gray. Niobrara river, August 15th. 
Oenothera spinulosa , var. Drummondii. Loup fork of the Platte, July. 
Gayophytum ramossissimurn, Torr. and Gray. Black hills, September 10th. 
Ludwigia palustris, Ell. Wet places in Platte valley, near mouth of Loup fork. 
Gaura coccinea, Nutt. Throughout the territory; different forms, canescent. Very 
small-leaved, or almost glabrous, with larger leaves. 
Gaura parviflora, Dough Bad Lands and Yellowstone country. 
Gaura biennis, Linn. Along Missouri river to Council bluffs. 
Gircea Lutetiana, Linn. Bad Lands. 
Myriophyllum spicatum , Linn. Common in ponds throughout the Upper Missouri. 
Hippuris vulgaris , Linn. In standing pools, Upper Missouri. 
LOASACEiE. 
Mentzelia ornata, Torr. & Gray. Common on bluffs about Fort Pierre. 
Mentzelia nuda , Torr. & Gray. Bad Lands. 
CACTACE2E. 
Mamillaria vivipara , Haw. From the mouth of White river to the Yellowstone. 
In the bottom lands it forms large csespitose masses, but on the arid hills along 
the Yellowstone a simple depressed variety is noticed; both belong to the sub¬ 
species which I have named vera, and the latter may be distinguished as var. 
simplex . 
Mamillaria Nuttalli,J&ngl., forma borealis , Cactus mamillaris, Nutt., Mam. simplex, 
Torr. & Gray. On White river, Fort Pierre, &c. 
Opuntia Eafinesqui , var. fusiformis , Engl. & Big. Near Big Bend of the Missouri, 
below Fort Pierre. 
Opuntia Missouriense, D. C. Different forms noticed in the Synopsis of the Cactaceee 
of the United States. (Proceedings Am. Acad. vol. iii, 1856.) a, rufispina ; b, 
platycarpa; c, microsperma ; d, subinermis. Found all over the territory ex¬ 
plored by the Expeditions. Durion’s hills was about the most eastern locality 
of this species. 
Optontia fragilis, Nutt. D. C. Bad Lands to Yellowstone. This species is very nearly 
allied to the last, and not to the glomerate Opuntice , with which it is usually 
united. It is seldom found in flower or fruit, being abundantly propagated by 
the fragile joints which even the wind breaks and scatters. The fruit is at first 
fleshy, and becomes dry only at last, while the fruit of Opuntia Missouriensis be¬ 
comes dry and papery as soon as ripe. 
