[O. filipendula] (hanging filaments); Fig. 81.—Stems prostrate, about 1 ft. high, spreading; joints flat, round or oval, about 3 in. long, often less, milky-green in colour. Cushions ½ in. apart, composed of a little tuft of white woolly hair, a cluster of erect, rather long bristles, like a small shaving-brush, and all pointing upwards; spines usually only one in each cushion, and this is slender, deflexed, white, and from 1 in. to 2 in. long. Sometimes the joints are wholly spineless. Flowers 2½ in. in diameter, purplish, very handsome, produced in May and June. Fruit not known. The roots of this species bear tubers often 1 in. in thickness, and several inches in length, and these tubers will grow into plants if severed and planted. It requires stove treatment. Native country, Mexico.
FIG. 81.—OPUNTIA FILIPENDULA
[O. frutescens] (shrubby).—A thin-stemmed, copiously-branched species. Joints almost continuous, like ordinary branches, from 2 in. to 6 in. long, the thickest not exceeding ¼ in. Cushions on raised points or tubercles, each consisting of a small tuft of hair, inclosed in a row of bristles, and one long, central spine, often exceeding 2 in. in length. When young, the spines are inclosed in a thin, bony sheath. Flowers scattered along the younger branches, 1 in. across, greenish-yellow, borne in June. Fruit 1 in. long, pear-shaped, smooth, scarlet, with tufts of bristles all over it, and a depression in the apex. Mexico. This forms an interesting pot-plant when properly cultivated. It should be grown in a warm greenhouse.
[O. Grahami] (Graham's).—This is one of several species of Opuntia which are remarkable in having thick, fleshy roots, not unlike those of the Dahlia. The joints are 2 in. long and 1 in. in diameter, cylindrical, with adpressed tubercles, ½ in. or more long, each tubercle bearing a tuft of long, straight, radiating spines. Flowers 2 in. across, yellow, borne on the ends of the ripened joints in June. Fruits 1½ in. long and ¾ in. wide, covered with stellate clusters of short, bristle-like spines. This plant is a native of Mexico, and is a recent introduction. From the nature of its roots, which are no doubt intended to serve as reservoirs for times of extreme drought, it should be grown in well-drained, sandy soil, and kept quite dry all winter. It requires stove treatment.
[O. horrida] (horrid).—An erect, stout-stemmed plant, with flattened, green joints, about 5 in. long by 3 in. wide. Cushions 1 in. apart, composed of short, reddish bristles, and long, tawny red spines, about eight in each cushion, and of a peculiarly ferocious appearance—hence the specific name. The stoutest spines are 3 in. long, and are sharp and strong as needles. This species (which is probably a native of Mexico) is deserving of a place in collections of Cactuses because of the character of its spines. Probably it is only a variety of O. Tuna. It requires warm-house treatment.
[O. hystricina] (porcupine-like).—This beautiful species was discovered in the San Francisco Mountains mixed with O. missouriensis, to which it is nearly allied. It is spreading in habit, the joints 3 in. to 4 in. long and broad; cushions ½ in. apart, rather large, with numerous spines, varying in length from ½ in. to 4 in., and short, yellowish bristles. Flowers large, yellow. Fruit 1 in., long, spiny. This plant is not known in English collections, but it is described by American botanists as being attractive and a free grower. As it is found along with O. missouriensis, it ought to prove hardy in England.
[O. leptocaulis] (slender-stemmed).—This little Mexican species is chiefly remarkable for its fragile, numerous, twig-like joints, thickly dotted with tubercles and numerous spirally-arranged cushions of reddish bristles, with long, grey spines. It does not flower under cultivation. Requires stove treatment.
[O. leucotricha] (white-haired).—An erect-stemmed kind, with flattened joints, ovate or oblong in shape, and bearing numerous cushions, ½ in. apart, of short bristles, with a large, central spine, and a few others rather shorter. When young these spines are rigid and needle-like; but as they get older they increase in length, and become soft, and curled like stiff, white hair. Young plants are noticeable for their small, subulate leaves of a bright red colour, whilst old examples are almost as interesting as the Old Man Cactus (Pilocereus senilis), the long, white, hair-like spines of the Opuntia hanging from the older joints in much the same manner as they do from the upper part of the stem of the Pilocereus. Flowers yellow, produced in June. This species is a native of Mexico, and requires stove treatment. Seeds of this, and, indeed, of a large proportion of the cultivated Opuntias, may be procured from seedsmen, and as they germinate quickly, and soon produce handsome little plants, a collection of Opuntias is thus very easily obtained.
[O. macrocentra] (large-spurred).—A flat-jointed species, growing to a height of 3 ft.; the joints large, almost circular, thinly compressed, and usually purplish in colour. Cushions about 1 in. apart, with spines often 3 in. long, of a greyish colour, and generally pointing downwards. Flowers 3 in. across, bright yellow; they are developed in May and June, on the upper edges of the youngest joints. This plant is a native of Mexico; it is at present rare, but the unusual colour of the joints, its compact, freely-branched habit, the extraordinary length of its spines, and the size of its flowers, ought to win for it many admirers. It is easily grown if kept in an intermediate house. Plants of it may be seen in the Kew collection.