The prostrate stems, three to nine feet long, lie flat on the ground with their tips upturned, resembling huge caterpillars. They grow in light sandy soils or sand, and root from below, the tips of the stems elongating and growing forward, the bases of the stems dying; thus the plant slowly moves forward over the sand. These prostrate stems, two or three inches in diameter, are very spiny, with fifteen radial and four central spines clustering an inch or so apart on the twelve to seventeen ridges which run lengthwise on the stems. These fierce, sharp thorns are dark brown and dull tan and turn white with age; the tips are translucent yellow. The radials are less than an inch long and flattened, the centrals grow to two inches in length, one very stout and strongly flattened, resembling a dagger and with a white body. The large flowers are bright yellow and grow four or fi. . . Read More