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Genus Echinocactus Link & Otto Most of the cacti in the genus Echinocactus live up to the meaning of the name. Some of them present among the strongest, most rigid spines found on any cacti, and most of them are covered with as complete a spine cover as is found anywhere. Their main spines are often made especially troublesome by being hooked at the end, but, because they are never barbed along the shaft, they are actually not as vicious as the much more slender spines of the Opuntias. Although these heavy spines are a feature of most of the Echinocacti, a few of them present more slender and flexible spines, and there are even a few spineless members of the group. These cacti are often known as the barrel cacti, and this term is a good one if it reminds us of their heavy, fleshy bodies and we do not let it limit our concept of them to something only barrel-shaped or barrel-sized. In size they may actually range from the huge, truly barrellike species usually thought of under this name and sometimes weighing hundreds of pounds to miniature forms essentially the same but, in some cases, only a few inches high when mature. In shape they are typically globular, although they may be very flattened, hemispherical, or sometimes heavily cylindrical. The exteriors of these cacti are typically firm and solid. They are shaped into from eight to more than twenty vertical or spiraling ribs, which may be broad or narrow, high or low, smooth and even throughout their lengths or undulating, notched, or cross-furrowed, but never completely interrupted. These ribs may be thought of as partly or completely fused tubercles, but with the fusing process always clearly visible. They are never rows of completely separate tubercles. The areoles are on the summits of these ribs. The presence of these ribs distinguishes the Echinocacti handily from the tubercled cacti, but not from the Cerei. For the characters which separate these, we have to look to the reproductive structures. All the Cerei produce the flowers on the sides of the stems, have a flower tube prolonged above the ovary, and also have a spiny ovary surface. Echinocacti, however, produce their flowers at or near the apex of the plant and have no distinct floral tube, and the ovary bears scales and sometimes wool, but not spines. It is harder to state differences between the Echinocacti and their other relatives. Ribs versus tubercles will usually do it, giving us a handy way to tell them from any of the Mammillarias and the members of the genus Pediocactus or genus Ariocarpus, but the genus Lophophora has what are best thought of as low ribs. These are small, spineless forms, different from the Echinocacti in various ways, but for clearly observable differences one has to look to their ovaries and fruits, which are naked, with no appendages of any kind. Most of the can also be separated from the Echinocacti by having such naked fruits, but several of them may have some scales on their fruits. genus Echinocactus 89 The genus Echinocactus is used here in practically the old and original sense given it by Link and Otto. It was originally described as a large and complex grouping of ribbed cacti which produced their flowers at or near the apex of the plant, where the blossoms grew out of the upper edges of the young spine-bearing areoles, and whose ovary and fruit surfaces were to some degree scaly. Schumann organized a series of subgenera within it, and later Britton and Rose divided the old genus up into a whole array of separate small genera, leaving the original name, Echinocactus, to cover in their system only a few species of large barrel cacti. The dividing process has continued until we have had at least twelve genera carved out of the old genus, among them Echinocactus (in the sense of Britton and Rose), Ferocactus, Homalocephala, Hamatocactus, Glandulicactus , Astrophytum, Sclerocactus, Thelocactus, Ancistrocactus, Neolloydia , Echinomastus, and Coloradoa. Due to the large influence of Britton and Rose’s publications these are no doubt the names that most cactus fanciers are familiar with today. Most people probably think of them as distinct and definite groupings, even though almost all would be hard-pressed if they had to try to tell the differences between them. Actually, these genera were erected upon very small differences and these differences are used to divide them so arbitrarily that, for instance, the...

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