Cacti of the Southwest

Genus Opuntia

Genus Opuntia Miller Placedlastinthisaccountisthelargegenus,Opuntia.Those who deal in matters of primitive versus advanced and theories of development tell us it should really be the first United States genus considered. The Opuntias are generally regarded as more primitive than the cacti we have already enumerated, and they also certainly deserve first place for their success. In over half of our states Opuntias are the only cacti found, and it is these cacti which enable us to say that cacti grow over almost the whole of the U. S. It is also the Opuntias which have escaped and flourished when introduced in such faraway parts of the world as the Mediterranean and north African countries, where they have become in many places a common part of the scenery, and Australia, where they have become the classic examples of plant invaders. But in spite of all this I am putting the genus Opuntia at the back of the book. This is in deference to the fact that most people find them the least interesting of the cacti, and many people associate them too strongly with unpleasantness to be able to appreciate them at all. Even many cactophiles lack in­ terest in them. It is not at all uncommon to find a fancier with a large collection of almost all other types of cacti, which in­ cludes not a single Opuntia, or only a few of the more exotic forms of the genus. Some collectors will travel hundreds of miles to get a new barrel cactus and on the way pass by twenty spe­ cies of Opuntias all in sight from the highway without even stopping to study them. There are very real reasons for this lack of interest in or ac­ tual avoidance of the Opuntias. I do not deny that. These cacti bring it upon themselves. The Opuntias make no attempt to please, and actually seem to be the experts in every means of antagonizing other organisms. They have several built-in features not shared by other cacti, which lose them friends. No doubt their most effective feature in provoking our dis­ like is one of their most obvious distinguishing characteristics— their possession of glochids. Glochids are special spines produced by this genus, usually in great numbers. They are distinct from the ordinary spines, which these cacti usually have in profusion as well, although there may be intermediates. The ordinary, larger spines of a cactus are dangerous enough, may inflict real injuries, and in cases where they are hooked or positioned at opposing angles on the plant, may hold one all too firmly, but they are not ordinarily barbed, and so they can usually be extracted from clothing or flesh rather easily if one is careful to remove them at the same angle they went in. But not so the glochids. These are comparatively very slender, often almost invisible they are so thin, and during development the cells covering the surface of each glochid loosen on their poste­ rior edges so that on the completed glochid they stand as hun­ dreds of firm, scalelike structures, each aimed obliquely to the rear—literally forming hundreds of tiny barbs to hold this tiny spear in whatever soft tissue it may pierce with its sharp point, and to rend and tear if there is an attempt to remove it. Add to this the fact that glochids, instead of being solidly attached to the plant like the other spines, become when mature so loosely held that they come off the areole at the slightest touch, and you have here instruments of torture parallel to and equally as diabolical as the spines of the porcupine. Man or beast usually comes away from a brush with an Opuntia bearing in his flesh whole clusters of these tiny, almost invisible glochids, which may not have been felt at all when they pierced the flesh, but which are firmly imbedded there—not deep, not even through the skin—but each one well set and with its shaft projecting so that any slightest touch to it or pressure on it makes the tiny barbs tear, and produces a pain like a needle prick. They are especially maddening because they are often so tiny that you can hardly see what is causing all the pain, and so delicate that if you do find them and take hold of them to remove them, their ends usually break off, leaving the tips imbedded, with only 160 cacti of the southwest the stumps to...