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 five inches in length, narrow and funnel-shaped, about two inches across. The fruit is very spiny; but the thorns fall away at maturity, and it becomes quite edible and is relished by Indians and Mexicans. How to grow Plant in sand or sandy soil, preferably fine sand, with the tips slightly upward, and keep the sand lightly moist. The plant requires a hot, sunny location and will grow out of doors in the Southwest where the temperatures do not drop more than a few degrees below freezing, and in hot dry conservatories and greenhouses where the temperatures drop lower. Senita, Zina, or Sina (_Cereus Schottii_) (Named from its appearance of old age, and for F. A. Schott, a botanical explorer of western United States) How to identify and how it grows These plants grow in colonies or patches in the mountain cañons, twenty to fifty stems in a clump, the dense branches interlocking in huge clusters twenty-five feet high and twenty feet or more across. The yellow-green stems are scalloped and cylindric, five or six inches in diameter, growing four to twenty feet or more in height, with five to nine ridges running lengthwise from top to bottom. On these ridges cluster the spines, silvery stout thorns about one-fourth inch long on the young plants; the older spines are really dense bristles, slender, flexible, symmetrically twisted, appearing like fine purplish gray bands, one and one-half to three inches long, and giving the appearance of old age. The flowers are shaped like a bell an inch and a half long and about as broad, pale pink and cream-white petals shading into deep pink at their tips, opening only at night. The fruit is globose, an inch or more in diameter, of a deep reddish tinge, and fleshy. How to grow