With this change of the surface, some change is observed in the vegetable products of the soil. Here {149} we first saw a new species of prickly poppy,[99] with a spreading white flower, as large as that of the common poppy of the gardens. The aspect of this plant is very similar to that of the common poppy, except that the leaves are covered with innumerable large and strong prickles. When wounded it exudes a thick yellowish sap, intensely bitter to the taste. On the summits of some of the dry sandy ridges, we saw a few of the plants called Adam's needles, (yucca angustifolia) thriving with an appearance of luxuriance and verdure, in a soil which bids defiance to almost every other species of vegetation. Nature has, however, fitted the yucca for the ungenial soil it is destined to occupy. The plant consists of a large tuft of rigid spear-pointed leaves, placed immediately upon the root, and sending up in the flowering season, a stalk bearing a cluster of lilliaceous flowers as large as those of the common tulip of the gardens. The root bears more resemblance to the trunk of a tree, than to the roots of ordinary plants. It is two or three inches in diameter, descending undivided to a great depth below the surface, where it is impossible the moisture of the earth should ever be exhausted, and there terminates in numerous spreading branches. In some instances, the sand is blown from about the root, leaving several feet of it exposed, and supporting the dense leafy head, at some distance from the surface.[100] [99] Argemone alba, a large plant, very distinct from A. mexicana.—JAMES. [100] Other plants found here, were the great sunflower Helianthus _giganteus_, Asclepias _obtusifolia_, Ph., A. _viridiflora_, Ph., A. _syriaca_, and A. _incarnata_, Amorpha _canescens_, N., Erigeron _pumilum_, N., A. Veronica approaching V. _deccabunga_ Scuttellaria _galericulata_, Rumex _venosus_, N., and several which are believed to be undescribed.—JAMES. Several bisons and other game, had been seen in the course of the day, but nothing taken. As our provisions were now exhausted, it was resolved to remain encamped where we were, while parties were sent out in different directions to hunt.[101]