The two cousins in the same genus, so to speak, will be found upon examination to differ greatly in several respects. While the Prickly Pear is built up of thick or flattened platelike joints which sometimes look like pancakes, with the spicules and spikes growing from little clusters over the surface (which by the way are most treacherous), the structure of the Cholla is found to be cylindrical, with very prominent tubercles. Since the Cholla is a very fascinating, mysterious, and unique member of the great cactus clan it will be well to be a little graphic in his description, for he is all that we may say about him, and more. He has as a rule a short main stem or trunk, from which branch many grotesque, weird-looking arms and legs that cause the whole plant to resemble a dwarf tree though it is typically shrubby in habit. A few of these fantastic forms have the joints club-shaped, sometimes quite slender, and these types are intermediate between the Prickly Pears and the Cholla, growing mostly as prostrate shrubs rather than as dwarfed trees. Prickly Pears and Cane Cacti alike have only one kind of spines in the areolas, though these are usually of several lengths, and both bear spicules along with their thorns. In the Cholla the tubercles are arranged spirally on the cylindrical joints, each bearing an areola which in turn has the spines and spicules and also the small, greatly reduced fleshy leaves half an inch long or longer; these always wither and fall off in a few days, showing no doubt that they are but remnants from an earlier age, when possibly the prehistoric cactus bore much larger leaves. Cholla thorns have very thin and transparent sheaths, which persist unless destroyed or rubbed off, thus differing from Prickly Pear thorns. Cholla spines are not messengers of harmony, nor do they welcome the tenderfoot tourist in his journey across the desert, for sheathed Cholla thorns constitute the most treacherous and dangerous of the cactus spines, a formidable fortress of strong, sharp, dangerously recurved spikes; and woe to the careless stranger who is inadvertently stabbed by one of these terrible Cholla swords! We have noted that the Prickly Pear blooms open in the early morning, closing in late afternoon with one or two exceptions. Among the very unusual Cane Cacti the opening of the flowers seems to be on a sort of schedule, for we observe that they unfold at different times, as at eight o’clock in the morning, at nine, at ten, at one o’clock, at three, and at four, then all close in the evening usually never to open again. So if you are to see this phenomenon you will have to be on time, for Cholla never wait. The flowers open wide very quickly, in the course of fifteen or twenty minutes, especially on bright sunshiny days. An occasional Cholla may bloom for the second day, but this is a very uncommon occurrence.