singly, in notches along the margins of the young, ripened joints; in the knotted, Samphire-like kinds, they are borne on the ends of the branches; and in those with short, fleshy, leaf-like joints, they are usually placed on what appear to be flower-joints.  Although the branches of these plants are usually altogether unlike the rest of the Order, yet occasionally they develop joints which are furrowed, and bear clusters of spines exactly as in the commoner forms of Cactuses.

The geographical distribution of Rhipsalis is exceptional.  It is the only genus of Cactuses that has representatives in the Old World, excluding, of course, those which have been introduced by man.  The bulk of the kinds of Rhipsalis occur in Central and South America, and the West Indies; but one—­viz., R. Cassytha—­is also found in Africa, Mauritius, Madagascar, and Ceylon, as well as in tropical America.  Several other species are found in Madagascar, some of them only recent discoveries.  The occurrence of similar or even identical plants in tropical America and Madagascar has its analogy in the Animal Kingdom as represented in the two countries.

Cultivation.—­All the species appear to grow well and flower freely under cultivation, the slowest grower being, perhaps, R. sarmentacea.  In their natural homes they are invariably found either on trees or rocks, seldom or never on the ground; but in greenhouses they may be grown in pots, a few being happiest when suspended near the glass.  They do not like bright sunshine, nor should they be kept in a very shaded, moist position.  There is a good collection of kinds in the Succulent-house at Kew.

Propagation.—­Seeds of Rhipsalis ripen freely, and these, if sown on sandy soil, and placed on a shelf in a warm house, germinate in a few days.  The development of the seedlings is exceptionally interesting, as the vegetative organs of all the kinds are very similar, and Cactus-like; the gradual transition from this character to the diverse forms which many of the species assume when mature is quite phenomenal.  Cuttings will strike at almost any time, if planted in sandy soil and kept in a close, warm house till rooted.  Some of the kinds thrive best when grafted on to a thin-stemmed Cereus.  Treated in this way, R. sarmentacea makes 6 in. of growth in a season; whereas, on its own roots it would take about five years to grow as much.

The following is a selection of the species cultivated in gardens.  The genus Lepismium is now included in Rhipsalis.

Species.

R. Cassytha (derivation not known).—­A pendent shrub, 4 ft. or more high, growing on rocks and the mossy trunks of trees.  Branches numerous, flexuous, with small branchlets or joints springing from the ends in clusters, smooth, round, the thickness of whipcord, leafless, with numerous brown, dot-like marks scattered over the surface; under a lens these dots are seen to be tufts of very fine hairs.  Flowers on the sides of the young branches, small, greenish-white, short-lived; they are developed in September, and are succeeded by white berries, exactly like those of the Mistletoe, whence the name Mistletoe Cactus, by which this species is known.  An interesting and easily-grown warm greenhouse plant, native of tropical America, Africa, &c.  It was introduced in 1758.