O. brachyarthra (short-jointed); Fig. 78.—­A dwarf-growing, singular-looking plant, with short, tumid joints from 1 in. to 2 in. long and wide, and nearly the same in thickness.  The shortness of the joints, together with their growing on the top of each other, has been not inaptly compared to a jointed finger.  Cushions very close together, composed of short, white and yellowish bristles, and stout, terete spines, 1 in. or more long, set on little tubercles.  Flowers 1 in. in diameter, with about five sepals, eight or nine petals, and a five-rayed stigma; they are borne on the apices of the topmost joints.  This species is worth growing on account of its peculiar stems and the length of its white spines.  It is a native of New Mexico, and has been recently introduced to Kew, where it is cultivated among the hardy kinds, and also in the greenhouse.

[Illustration:  Fig. 78.  Opuntia brachyarthra.]

O. braziliensis (Brazilian).—­The peculiar habit and mode of growth at once distinguish this species.  It rises with a perfectly straight, erect, slender, but firm and stiff, round stem, to a height of from 10 ft. to 30 ft., tapering from the base upwards, and furnished all the way up with short, horizontal branches, spreading about 3 ft. all round, like an immense candelabrum.  Spines long, subulate, very sharp, ash-coloured, in clusters.  Joints broadly oblong, margins wavy; they resemble leaves, or the thin, leaf-like joints of a Phyllocactus, with the addition of long, whitish spines on both sides.  Flowers 11/2 in. in diameter, lemon-yellow, very freely produced on the younger joints during May and June.  Fruit as large as a walnut, spiny, yellow when ripe.  This species is a native of Brazil, whence it was introduced in 1816.  It may be recommended for large, airy houses, as it grows freely, and forms a striking object when arranged with foliage and flowering plants of the ordinary kind.  Its fruits are edible.

O. candelabriformis (candelabrum-shaped).—­Stems erect, 5 ft. to 8 ft. high; joints flat, almost circular, about 6 in. in diameter, glaucous-green, densely clothed with numerous cushions of white, bristle-like spines, a few in each cushion being long and thread-like.  Flowers not known on cultivated plants.  This sturdy species is a native of Mexico, and succeeds well if planted on a little rockery or raised mound in a warm house, where, properly treated, it branches freely, and forms a dense mass of circular joints.  It is one of the most useful of the larger Opuntias for cultivation in large houses.

O. clavata (club-shaped).—­Stem short; joints club-shaped, 2 in. long and 1 in. wide, narrowed almost to a point at both ends.  Cushions 1/4 in. apart, composed of numerous spines, varying from short and bristle-like to 1 in. in length, stout, flattened, and spear-like.  Leaves 1/4 in. long.  Flowers yellow, 11/2 in. across.  Fruit 11/2 in. long, lemon-yellow when ripe, and covered with stellate clusters of white, bristle-like spines.  New Mexico, 1854.  A stove species, remarkable for the strength and form of its central spines, which are spear or dagger-shaped.