Cacti and Succulents

It will be noted that the terms 'cacti' and 'succulents' are both used in the title of this chapter. This is unavoidable when dealing with this subject, because it has become the practice to regard these as two groups of plants, but technically it is wrong to speak of' cacti' and 'succulents' because cacti themselves are succulents. Succulents are by definition plants that have originated in habitats where long periods of drought are experienced, calling for them to survive without water. This they do by becoming adapted so that they can reduce the loss of water by evaporation from their tissues and store water. This is done by developing thick, fleshy tissues within their stems and/or leaves, that are enclosed by a thick skin or bark. Another device that these plants have developed in order to give them the power to conserve their water supplies is to adopt shapes that have the maximum volume with the minimum surface area, so that evaporation from the latter is minimized. In consequence, succulents tend to be rounded in shape, because, as the mathematicians among the readers will appreciate, a sphere meets this condition to the fullest extent, i.e. it has the largest volume in relation to its surface area of all shapes.

Many succulents have no leaves, but their normal functions, such as transpiration and converting water and carbon dioxide, with the aid of sunlight and chlorophyll, are carried out by the green fleshy tissues of the stems. It is important to appreciate fully that certain plants have evolved these succulent properties over the ages because of the living conditions in which they have found themselves. In consequence, there is no specific family of succulents. Plants with succulent qualities are found to be members of at least twenty widely varied plant families. Some have only a few succulents, while the others, such as the cactus family, are entirely composed of them. On the other hand, others such as aloes and haworthia, which belong to the lily family, the kleinias, which are compositae, and agave, a member of the narcissus family, are distributed through a range of botanical families.

While dealing with definitions it should be pointed out there are two types of cacti popular for interior decoration. The first is known as Desert Cacti and, as their name suggests, they are the ones found living in the hot, arid conditions of the desert. The second type is known as Epiphytes. In their natural habitat they grow on trees and rocks. They are not parasites, but derive nutriment from decaying vegetable matter. Some of the latter species have been highly developed and there are now available some very lovely flowering hybrids, a number of which are scented.

Cultivation
Generally speaking, succulents enjoy an open soil that drains very quickly. The desert or terrestrial type like a growing medium, comprised of equal parts of sifted heavy loam, coarse sand and a mixture of four parts finely broken brick and one part old mortar rubble. Epiphytic cacti prefer their soil to include very generous proportions of sifted peat and well-rotted cow manure added to the above medium. Of them, the epiphyllum cacti in particular dislike excess lime, so it is as well to omit the mortar rubble in their case.

Desert cacti like a very sunny position, whereas the epiphytes, because they grow naturally in woodlands, need less sun, but in order to ensure that they bloom well they should be in the sun for part of the day. For the same reason, they like to be watered freely, particularly in the spring when the buds are forming, but after flowering is over they should not be watered for about a month in order to give them a rest. When this period has passed watering should be resumed. While they should not be allowed to dry out, they do not need water during the winter, particularly if they are placed in a cool position. Desert cacti in their natural surroundings are subject to heavy rain and the soil dries out before more comes. They are therefore not used to having their roots in soil that remains damp for long periods. To simulate these conditions, desert cacti should be watered regularly during spring and summer, but the compost should be allowed to dry out before watering is repeated. It has been shown that this alteration of wet and dry spells encourages flowering. Like epiphytic cacti, they should be given very little water during the winter.

Although desert cacti enjoy high temperatures in the summer, they can be kept at quite a low temperature in the winter, providing they do not freeze, but in the case of epiphytes, the temperature should not fall below 45°F (7°C).

Cacti are able to withstand to a small extent gas and other obnoxious fumes. They do, however, tend to get dusty, particularly when they are knobbly and bristly. They are best cleansed by stroking with a soft brush. Their containers should be turned regularly in order to prevent uneven growth.

Cacti are generally easy to grow and, in the case of many, to multiply. They will resist a considerable amount of neglect. They are therefore ideal for house plants, when spare time is limited. A large number of them are dwarf and have small growth patterns, so that they are invaluable for table decorations in places where thee space is restricted. They also make the most interesting and attractive dish gardens, but because of their soil requirements and growing conditions being different to those of most other indoor plants, they should not be mixed with them.

A Selection of the More Popular Cacti and Other Succulent Plants Aeonium haworthii is easy to grow and increase by stem cuttings. It carries rosettes of leaves at the top of its stems. It makes an attractive bush. Other species suitable for indoor pot culture are A. arboreum and A. tabuliforme.

Agave americana 'Variegata'. Although this plant will flower after many years, it is grown for the loveliness of its leaves, which are striped green and yellow. It is easy to grow and is commonly known as the Century Plant or American Aloe. Aloe variegata (Partridge-breasted Aloe, Falcon Feather, Tiger Aloe) is mainly attractive for its rosettes of triangular-shaped, grey-green leaves with whitish spots. It grows easily to an eventual height of twelve inches and is robust. A. arborescens, A. brevifolia and A. humilia are other aloes recommended for pot culture.

Astrophytum myriostigma (Bishop's Mitre). This pleasant green-skinned plant with white felted flecks is easy to grow. It normally has five ribs and grows large yellow flowers, usually from the crown.

Cephalocereus senilis. It is commonly called 'Old Man Cactus', because of the long, wavy, silver-grey and whitish hair with which it is covered.

Cereus jamacaru. This desert cacti is an intriguing angular, columnar plant with bluish-coloured stems. It rarely flowers indoors, but being rather taller, it is an attractive accent plant in an arrangement.

Ceropegia woodii (Hearts Entangled). This succulent plant is a trailer, which is mainly grown for its foliage. Its leaves, which are heart-shaped, grow in pairs along its long, reddish-brown stems. The upper surfaces of the leaves are dark green with a heavy grey mottle, making them appear silvery.

Chamaecereus silvestrii (Peanut Cactus). It is a good species for a beginner. It has cylinder-shaped, prostrate stems or branches, pale green in colour with soft spines. In early summer it produces funnel-shaped, orange-vermilion flowers, which grow direct from these branches. It should be kept cold (32°F (o°C) will not harm it) during the winter.

Cotyledon undulata. This succulent plant has the most attractive large leaves, which are narrowed at the base and fan out with a wavy edge. They are covered with white powdery bloom, which gives them a pretty, greyish look. The plant should not be watered from above, otherwise this is washed off. Its flowers are pendant and bell-shaped and cream with red stripes in colour.

Crassula arborescens (Tree Crassula) is a tallish plant, which is a good accent in a dish garden. Its leaves are greyish-green and dotted red.

C. perforata, with its greyish-green leaves strung like beads along its prostrate stems, C. argentea and small-growing, tree-shaped C. lycopodioides, with its square stems covered with tiny green leaves, are also recommended for pots.

Echeveria glauca (E. secunda glauca) has beautiful glaucous rosettes of blue-green, margined red leaves, from which rise on arching stems its bright red and yellow flowers. It makes an excellent centre-piece for an arrangement. Other echeveria that grow successfully indoors are E. derenbergii, E.fulgens (E. retusa) and E. pulvinata.

Echinocactus grusonii (Barrel Cactus, Hedgehog Cactus) is a popular, golden-spiked, round-shaped cactus, which seldom flowers indoors, but is nevertheless very decorative.

Echinocereus blanckii. Although upright when young, its dark green, 12-14-inch long and over 1 inch in diameter branches eventually become prostrate. They have groupings of 8 or 9 black or white spines. It is very beautiful with its abundant, 4-inch long, violet flowers. It is hardy and will sometimes grow outdoors, but needs good light. A slower growing species, E. gelmannii, is appreciated for its thick covering of yellow to red-brown spines.

Echinopsis eyriesii. This is a very easy-to-grow favourite. When young it is almost spherical in shape with a dark, shiny green skin with spines on its ribs. Its flowers are white and grow at the top of high stems.

Epiphytic Cacti
Aporocactus flagelliformis (Rat's Tail Cactus) has long, glossy, green, later grey-green, narrow stems, from which emerge three-inch long reddish-purple flowers, usually at the beginning of spring.

Epiphyllum ackermannii (Orchid Cactus) and its varieties. This is a highly developed epiphyte. The species has finely scalloped, dark-green leaves (actually they are flattened stems), with very few spines and produces the most gorgeous, very large, deep-crimson flowers. It has a number of very attractive hybrids.

Rhipsalidopsis rosea (Easter Cactus) is like a miniature Christmas Cactus (see below).

Rhipsalis houlletiana has long, thick stems, which can be either supported or allowed to hang over the side of a container. It is rounded at the bottom and flattened at the top. It has serrated edges from which its creamy-white flowers, with a red eye, spring. They are followed by red berries.

Schlumbergera gaertneri, more recently termed Rhipsalidopsis gaertneri (Whitsun Cactus). It has the same habit as Zygocactus truncatus (see below). Its leaf-like green stems have purplish, notched edges and not many bristles. Its scarlet and violet flowers appear in late spring. Another attractive species is Schlumbergera bicolor, which flowers in the winter.

Zygocactus truncatus is the very popular Christmas Cactus, so called because at that time it flowers at its best. It is a pendulous, spreading plant with long segmented stems, from the terminals of which grow vivid cerise-pink flowers.

Euphorbia splendens (Crown of Thorns) is a shrubby plant with brown, branching spikes. It has bright-scarlet bracts surrounding tiny yellow flowers. It is deciduous, but E. bojeri is evergreen and flowers most of the year.

Gasteria verrucosa is a favourite succulent plant. It is tufted and has two ranks of thick, fleshy, three-sided, dull-grey leaves, with whitish wart-like protuberances.

Gymnocalycium quehlianum is the shape of a flattened sphere and has ribs, which are composed of knobs, from which brownish spines radiate. Its skin is dull grey-green, becoming brownish in the sun. At its crown it produces funnel-shaped, whitish flowers, that have a carmine centre.

Kalanchoe blossfeldiana is one of a very large species. It has dark-green, red-edged succulent leaves, from which grow panicles of scarlet flowers on slender, foot-tall stems during the winter. It needs plenty of water during the growing season. K. kewensis and K. tomentosa are also suitable for growing in pots.

Kleinia articulata (Candle Plant) has attractive glaucous-blue, jointed, half inch thick stems, from which grow small, fleshy, green leaves. Some stems hang over the side of the container. The flowers, which are yellowish, have an unpleasant smell and should be removed.

Mammillaria bocasana. This member of the Mammillaria species, which includes some of the most popular cacti, is commonly known as the Pincushion Cactus. It is a small rounded plant, which produces freely blue to green, short sideshoots, which are completely covered with fine white spines. As a result, the whole mass acquires a bluish-grey colour. Through this covering yellowish flowers with a central reddish stripe on the outer petals, appear. Other species of interest to indoor plant enthusiasts are M. 'Bicolor', M. elegans 'Aurei-spina' which has yellow spines, M. kewensis, M. prolifera and M. winteriae. All these mammillaria are easy to grow.

Opuntia microdasys (Prickly Pear, Bunny's Ears). This is probably one of the most intriguing and charming cactus for growing indoors. It is a shrub-like plant composed of flattened oval pads.  They are emerald green in colour.  They are covered regularly in squares with areoles (pincushion-like knobs) from which emerge a large number of very small, yellowish-brown, barbed bristles, giving the plant a woolly appearance. It needs to be very sparingly watered in the winter but otherwise it is a tolerant, easy-to-grow plant.

Pachyphytum oviferum. Being closely related to the echeverias, this species has rather similar flowers. The leaves, however, are much more fleshy and round. Those of P. oviferum are covered in a white bloom, which gives them the appearance of sugar-dusted acid-drops. This is a most attractive feature, which must be preserved by taking care that they do not get wet when being watered.

Rebutia marsoneri. The body of this cacti is flattened spherical in shape, ultimately attaining a height of about n\ inches and a diameter of about 3^ inches. Its colour is pale green with its base eventually becoming grey. With its golden-yellow flowers breaking from intensely red buds, this cacti was a great discovery because hitherto known Rebutias had flowers that were varying shades of red. Another very attractive little plant, which is easy to grow is R. pseudodeminuta. It is a flattened sphere no more than 2^-inches in diameter. It flowers very abundantly with red and golden flowers just over an inch across. Another that can be recommended for pot culture is R. haagei.

Sedum adolphii is a low semi-shrub, which has fleshy or semi-woody branches. Its leaves are fleshy, pale green in colour and oval in shape. They are about 1^ inches long and \—\ inch across. Part of the charm of this plant lies in the delightful manner in which these leaves, growing at the end of each branch, form a close cluster. Other species that make good house plants are S. allantoides, which has whitish-green, stout keel-shaped leaves, and S. pachyphyllum, with similarly shaped leaves which are green, tipped with red.

Pebble Plants
These plants, which are all members of the South African mesembryanthemum family, grow naturally among stones, which they closely resemble. There are several that are of interest for growing indoors.

Conophytum pearsonii is, next to Lithops (see below), among these types of plants comparatively easy to grow. It forms unusual clumps of rounded stems, which are broadly conical with a flattened crown. These stems are more like small apples in shape than stems. They are smooth and bluish-green in colour. The flowers, whch appear during September and October, the beginning of the growing season, are pale violet in colour. During their resting period in the summer, a new body forms inside the old stem, absorbing all the substances from it until all that remains is the skin, which dries and protects the new plant from the heat of the sun and excessive water evaporation. The resting plant during this period looks like a stone. Hence it is known as a 'living pebble'. Another attractive species is C. bilobum, which has yellow flowers.

Lithops bella. Before it blooms it looks very much the same as a round pebble. It consists of two fleshy, plump leaves, which are about an inch high. It resembles in shape a roundish pebble that has a very noticeable fissure across its flattened top. In the autmn there grows from this crevice a daisy-like white flower, which is about an inch in diameter. The new leaves grow inside the old ones, exactly as described for C. pearsonii.