The thirteen species included in the genus Pereskia differ so markedly from all other kinds of Cactus, that at first sight one can scarcely believe they are true Cactuses, closely related to Cereus and Epiphyllum. They have erect or trailing stems and branches, and usually form dense, large bushes; the branches are woody and thin, and bear large, laurel-like leaves, which remain on the plants several years--so that they may be termed evergreen. They have, however, the spine-cushions, the tufts of woolly hair and stout spines, and the floral characters which distinguish Cactuses from other plants; they are also succulent, the leaves and young branches being soft and fleshy.

They appear to have the same peculiar provision for enabling them to bear long periods of drought without suffering that characterises the more familiar forms of Cactuses. The development of the spines in this genus is different from what takes place in all other spiny plants of this order. In the latter the spines are stoutest and most numerous on the younger parts of the plant, the older or woody parts being either spineless, through having cast them, or much less spiny than when they were younger. Thus, in Opuntia we find few or no spines on the old parts of the stems of even such species as O. horrida, O. nigricans, &c. In Echinocactus, too, the spines about the base of old plants are much fewer, if not entirely cast off, than on the upper part. In Pereskia the contrary is the case. Taking P. aculeata as an example, this is best known in gardens as having branches about as thick as a goose-quill, with ovate leaves, at the base of which there is a pair of curved spines, in. long, and shaped like cats' claws. But this plant when it gets old has a stem 3 in. in diameter, and clothed down to the ground with cushions of spines fixed firmly in the bark, each cushion composed of from twenty to fifty spines, and each spine 1 in. or more in length.

From two to six new spines are developed in the centre of each healthy cushion annually. It would be absolutely impossible for any animal to climb an old stem of a Pereskia. In P. Bleo the spines are 2 in. long, and the cushions are much larger.

The flowers of Pereskias are borne singly or in panicles, at the ends of the young, ripened branches. In shape, each flower may be compared to a single Rose, the petals being flat and spreading, and the numerous stamens forming a compact cl.u.s.ter in the centre. The stigma is erect, and divided at the top into four or more rays. The fruit is a berry shaped like a Gooseberry, and covered with minute cl.u.s.ters of short bristles.

All the species are found in tropical America and the West Indies.

Cultivation.--Although several of the kinds of Pereskia are sufficiently ornamental to be deserving of a place in gardens as flowering plants, yet they are rarely cultivated--in England, at least --for any other purpose than that of forming stocks upon which Epiphyllums and other Cacti are grafted. Only two species are used, viz., P. aculeata and P. Bleo, the former being much the more popular of the two; whilst P. Bleo, on account of the stoutness of its stems, is employed for only the most robust kinds of grafts.

Propagation.--Both the above-named species may be propagated to any extent, as every bit of branch with a leaf and eye attached is capable of rooting and soon forming a stock. The practice among those who use Pereskias as stocks for Epiphyllums is as follows: Cuttings of P.

aculeata are planted in sandy soil, in boxes, and placed on a shelf in a stove till rooted. In about a month they are ready to be planted singly in 3 in. pots, any light soil being used; and each plant is fastened to a stake 1 ft. long. They are kept in a warm, moist house, all lateral shoots being cut away, and the leader encouraged to grow as tall as possible in the year. From December the plants are kept dry to induce the wood to ripen, preparatory to their being used for grafting in February. Stocks 9 in. or 1 ft. high are thus formed. If taller stocks are required, the plants must be grown on till of the required length and firmness. Large plants may be trained against a wall or along the rafters in a warm house; and when of the required size, the branches may be spurred back, and Epiphyllums, slender Cereuses, and similar plants, grafted upon them. In this way very fine ma.s.ses of the latter may be obtained in much less time than if they were grown from small plants.

SPECIES.

P. aculeata (p.r.i.c.kly); West Indian or Barbados Gooseberry.--Stem woody, more or less erect, branching freely, and forming a dense bush about 6 ft. high. Young branches leafy; old ones brown, leafless, clothed with large cushions of long, stout, brown spines, sometimes 2 in. in length.

Leaves alternate, with very short petioles, at the base of which is a pair of short spines, and a small tuft of wool in the axil; blade 3 in.

long by 2 in. broad, soft, fleshy, shining green. Flowers semi-transparent, white, in terminal panicles; sepals and petals in.

long by in. wide; stamens in a large, spreading cl.u.s.ter, white, with yellow anthers. Ovary covered with small cushions of short bristles, with sometimes a solitary spine in the centre of each cushion. Fruit 1 in. long, egg-shaped, red, edible. There is a large plant of this in the Succulent House at Kew which flowers almost annually, but it has never ripened fruits. In the West Indies it is a very common shrub, whilst at the Cape of Good Hope it is used for fences--and a capital one it makes.

P. a. rubescens (reddish).--This variety has narrower, longer leaves, which are glaucous-green above and tinged with red below; the spines on the old stems are shorter and more numerous in each cushion. This requires the same treatment as the type.

P. Bleo (native name); Fig. 87.--A stout, branching shrub, having an erect stem, 3 in. or more in diameter, with green bark and very large cushions of spines; cushion a round, hard ma.s.s of short, woolly hair, from which the spines--about fifty in each cushion--radiate in all directions; longest spines 2 in. or more in length; one or two new ones are developed annually, and these are bright red when young, almost black when ripe; young branches in. to in. in diameter. Leaves in.

apart, 3 in. to 6 in. long by 1 in. to 2 in. wide, oblong, pointed, with short petioles, and a small tuft of short, brown hair, with three or more reddish spines, in the axil of each. Flowers on the ends of the young, ripened branches, cl.u.s.tered in the upper leaf-axils, each flower 2 in. across, and composed of a regular circle of rosy-red petals, with a cl.u.s.ter of whitish stamens in the centre. They remain on the plant several weeks. Native of New Grenada. Probably P. grandiflora is the same as this, or a slightly different form of it. A large specimen may be obtained in a year or two by planting it in a well-drained bed of loam, in a warm, sunny house. It blossoms almost all summer if allowed to make strong growth. Pretty little flowering plants may be had by taking ripened growths from an old plant, and treating them as cuttings till rooted. In the following spring they are almost certain to produce flowers. Plants 1 ft. high, bearing a cl.u.s.ter of flowers, are thus annually obtained at Kew. Fig. 87 represents a short, stunted branch, probably from a specimen grown in a pot. When planted out, the leaves and spine-cushions are farther apart.

[Ill.u.s.tration: FIG. 87. PERESKIA BLEO.]

P. zinniaeflora (Zinnia-flowered); Fig. 88.--Stem erect, woody, branching freely, the branches bearing oval, ac.u.minate, fleshy, wavy-edged, green leaves, with short petioles, and a pair of spines in the axil of each. Spine-cushions on old stems crowded with stout, brown spines. Flowers rosy-red, terminal on the ripened young shoots, and composed of a whorl of broad, overlapping petals, with a cl.u.s.ter of stamens in the centre, the whole measuring nearly 2 in. across. This species is a native of Mexico; it grows and flowers freely if kept in a warm house.

[Ill.u.s.tration: FIG. 88. PERESKIA ZINNIAEFLORA.]

CHAPTER XVI.

THE GENUS RHIPSALIS.

(From rhips, a willow-branch; referring to the flexible, wand-like branches of some of the kinds.)

About thirty species of Rhipsalis are known, most of them more peculiar than ornamental, although everyone is in some way interesting. They are remarkable for the great variety in form and habit presented by the different kinds, some of them much less resembling Cactuses than other plants. Thus, in R. Ca.s.sytha, the long, fleshy, whip-like branches and white berries are very similar to Mistletoe; R. salicornoides, with its leafless, knotty branches, resembles a Salicornia, or Marsh Samphire; another is like a Mesembryanthemum; and so on. The flowers are usually small, and composed of numerous linear sepals and petals, arranged more or less like a star, with a cl.u.s.ter of thin stamens in the centre, and an erect, rayed stigma. In the flat-jointed kinds, the flowers are developed 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 cl.u.s.ters 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. Ca.s.sytha--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 a.n.a.logy 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 gla.s.s. 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 a.s.sume 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. Ca.s.sytha (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 cl.u.s.ters, 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.

R. commune (common); Bot. Mag. 3763.--Stem straggling, branching freely, growing to a length of several feet. Branches jointed; joints varying in length, triangular, the angles compressed, and notched along the margins; notches regular, and bearing tufts of whitish hair. Strong plants produce joints over 1 in. in width. Flowers white, tinged with purple, springing singly from the notches, and composed of eight to twelve sepals and petals. Stamens and stigma erect, white, the latter four-rayed. This species is a native of Brazil, and was introduced in 1830; Flowering-season, October to December. It may be grown in a warm greenhouse, and treated as a basket-plant or as a small pot-shrub. Syn.

Lepismium commune.

R. crispata (curled).--Stem branching freely. Branches jointed and flat, like Epiphyllum. Margins of joints notched, and slightly curled.

Flowers small, white, produced singly, in November and December, in the notches on the younger joints. Fruits white, pea-like, rather rarely ripened. A free-growing, compact stove shrub, with a bright green, healthy appearance. The similarity of its branches to Epiphyllum led to its being included in that genus by Haworth.

R. c. purpurea (purple).--This variety has larger, broader joints, which are bronzy-purple in colour.

R. fasciculata (cl.u.s.ter-branched); Bot. Mag. 3079.--Stems terete, as thick as a goose-quill. Branches usually in cl.u.s.ters, and sometimes jointed, green, with small red dots and little tufts of fine, hair-like bristles. Flowers white, produced in March, springing irregularly from the older branches, small, star-like. Fruit a white berry. From its habit of growing on trees, and the character of its stems and fruit, this plant has been called parasitical. It is, however, only indebted to the tree on which is grows for moisture, for it thrives if planted in a pot or basket in ordinary soil, and kept in a stove temperature. It is a native of Brazil, and was introduced in 1831.

R. floccosa (woolly).--Stems as in R. Ca.s.sytha, but thicker, longer, and with the branchlets in compact cl.u.s.ters on the ends of the long, arching branches. The dots marking the position of the microscopic hair-tufts are in small depressions. Flowers and fruit as in R.

Ca.s.sytha, of which this might reasonably be called a variety. This species requires warm-house temperature.

R. funalis (cord-like); Fig. 89.--Stem straggling, branched. Branches numerous, composed of long, terete joints, rather thicker than a goose-quill, glaucous-green, slightly roughened on the surface, with depressions for the dot-like cushions. Branchlets usually fascicled and spreading. Flowers white, produced in spring, on the sides of the young joints, 1 in. across, large for the genus. Introduced from Central America about 1830. An easily-grown plant, st.u.r.dy, rather straggling, but very free-flowering. In old specimens the branches become semi-pendulous. It grows best when kept in a warm house. Syn. R.

grandiflora.

[Ill.u.s.tration: FIG. 89. RHIPSALIS FUNALIS.]

R. Houlletii (Houllet's); Bot. Mag. 6089.--Stems long, graceful, branching freely, round and twig-like, or with broad wings, as in Phyllocactus. Winged or flattened portions notched, and bearing a flower in each notch. Flowers stalkless, with pointed, straw-coloured petals, forming a shallow cup about in. across the top. Stamens and pistil white, with a tinge of red at the base. Flowering-season, November.

Under cultivation, this Brazilian species forms a small, straggling shrub, about 3 ft. high, but in its native woods its stems are many feet long, and pendulous from the branches of trees. It may be grown in a warm house, in a pot, and its branches supported by a stake; or its lower stems may be fastened against a piece of soft fern-stem, into which its numerous stem-roots penetrate freely. In the winter it should be kept almost dry. The flowers remain fresh for several days, and are fragrant. A well-grown plant, when in flower, is an interesting and pretty object. It is the most ornamental kind.

R. Knightii (Knight's).--Stems and joints as in R. commune. Wings of joints usually broad, with red margins, and the hair in the notches in a dense tuft, nearly 1 in. long, pure white, and silk-like. Flowers small, white. This species, which thrives best under warm-house treatment, is a native of Brazil, and is usually grown only for its curious, Cereus-like stems. It forms a straggling plant about 1 ft. high. Syn. Lepismium Knightii, Cereus Knightii.

R. mesembryanthemoides (Mesembryanthemum-like); Bot. Mag. 3O78.--A small, compact plant, with woody stems, densely covered with little fleshy, conical joints, resembling very closely the leaves of some of the Mesembryanthemums. They are green, with a few red dots, each bearing a very small tuft of the finest hair-like spines. The flowers are developed in March, from the sides of the small joints; they are in.

across, and yellowish-white. Fruit a small, white, round berry. Native of South America, whence it was introduced in 1831. When grown in a warm house, in a small, round, wire basket, filled with peat and sphagnum, this little Cactus forms a pretty tuft, which in the spring produces large numbers of white, star-like flowers.

R. myosurus (mouse-tailed); Bot. Mag. 3755.--Stems dependent, several feet long, branching freely, jointed, with three or four angles or wings; the angles flattened, reddish, notched in the margin, and bearing a tuft of white, silky hairs in each notch. Flowers small, yellow, tinged with red, springing from the notches; produced in July. Fruit not seen. A native of Brazil; introduced in 1839. This species resembles some of the angular-stemmed kinds of Cereus. It grows freely and flowers annually, if planted in a basket of fibrous soil, and suspended near the gla.s.s in a warm greenhouse or stove. It is attractive even when not in flower, owing to the form of its stems and the tufts of long, silky, white hair which spring from the notches. Syn. Lepismium myosurus.

R. pachyptera (thick-winged); Bot. Mag. 2820.--Stem woody; branches jointed, flattened as in Phyllocactus, with deep notches; width of joints, 2 in. or more. Flowers small, yellowish-white, borne singly in the notches in November. Fruit a small, white berry, rarely ripened. A st.u.r.dy, comparatively uninteresting stove plant, introduced from Brazil in 1830. Syn. Cactus alatus.

R. paradoxa (paradoxical).--Stems trailing, with numerous long branches of most extraordinary form. Imagine a three-angled, fleshy branch, often several feet in length, the angles winged, about in. deep, green, with smooth, reddish margins. At intervals of about 2 in. the branch has the appearance of having been twisted half round. There is no other plant with branches anything like these. Flowers produced in November, in the apex of the interrupted angles, small, white. Fruit seldom ripened. A native of Brazil, whence it was introduced in 1837. There is a fine example of this trained along a rafter in the Succulent-house at Kew.

The numerous branches hang down several feet from the rafter, and have a most extraordinary appearance. This species requires stove treatment.

R. penduliflora (pendulous-flowered).--A small, thin-stemmed plant, with smooth, green branches, no thicker than whipcord, and numerous fascicled or cl.u.s.tered, small joints, in. long, green, with red dots, angular when young. Flowers on the tips of the terminal joints, pale yellow, in. across, developing in August. Fruit white, Mistletoe-like.

This species was introduced from tropical America in 1877, and requires stove treatment.

R. p. laxa (loose).--This variety has the branches curving, and more pendulous; in other respects it resembles the type, and requires the same treatment.

R. pentaptera (five-winged).--Stems erect; branches stiff, long-jointed, with five wing-like angles, slightly spiral, the angles notched at intervals of 1 in. Flowers in the notches, in. across, white, produced in August. Fruit a white, Mistletoe-like berry. A curious plant from Brazil, and introduced in 1836. In stove temperature it forms a compact pot-shrub, 2 ft. high, and is worth growing on account of its singular stems.

R. rhombea (diamond-branched).--Stems and branches as in R. crispata, but without the wavy margins, and with more elongated joints. Flowers small, white, produced in the notches of the joints in November. Fruit a shining, milk-white berry. A compact plant from Brazil, worth growing for its bright green, leaf-like stems. It should be grown in pots, in stove temperature, and encouraged to form a globose bush.