Cacti and Succulents
Succulent plants are the camels of the vegetable world, storing up food and water to be used not on a rainy day, but during a period of prolonged drought. This may last for a few weeks or, in extreme cases, plants have survived without rainfall for over a year. This water can be stored in either the leaves or the stems of the plants, depending on the type. This gives rise to two distinct types of succulent plant, leaf succulents and stem succulents. The stem succulents usually have no leaves (except sometimes very small ones on young growth, soon falling off), and the green tissue of the stems takes over the work of the leaves to manufacture the food. Without leaves, the plants can reduce much of the water loss. The stems are usually very thick and full of water storage tissue, and are mostly either cylindrical or spherical in shape, sometimes being deeply ribbed. The ribs enable the plant to expand or contract as it absorbs or loses water.
Leaf succulents have plump, rounded leaves full of water storage tissue. They are often coated with wax, meal or hairs, helping to reduce water loss from their surfaces. Often these succulents have fleshy stems as well, but the leaves play the most important part in food manufacture.
The cacti, all belonging to one family, are the most popular group of succulent plants, but many other plant families have succulent members. Among the families whose succulent species are grown are the Crassulaceae, Aizoaceae, Euphorbiaceae, Asclepiadaceae, Liliaceae, and Agavaceae.
The cactus family is native to America; plants found in Europe and elsewhere have been introduced at some time in the past. There are three distinct types of plant, the pereskias, the epiphytes and the desert cacti, and these require different treatment because of their differing ‘home’ conditions. Except for the pereskias, they are stem succulents, having either no leaves or small temporary ones. Cacti are not all spiny plants, some being strongly armed while others are quite spineless. All cacti have areoles, small pincushion-like structures scattered over the stems. Spines, when present, off-shoots, and branches come from these areoles. This is the way to distinguish a cactus from another stem succulent, such as a euphorbia, which does not have areoles. Also all cactus flowers have the same general design, while those of other succulents differ enormously between the various families.
Pereskias The pereskias must have a brief mention here, as they are so different from other cacti. They are obtainable from the specialist nurseries, but not likely to be found in the local florist. They are interesting in that they are the only cacti which are not really succulents, and have normal leaves, rather like those of a privet, but possess spines and, of course, the characteristic areoles. The flowers bear a superficial resemblance to the wild rose. They are bushes and climbers from the tropical regions of north and central America, where they are used as hedging plants, and can be grown as pot plants, but to be really successful they need to be bedded out in a large greenhouse, where they can scramble up a wall or over a support. They need a winter temperature of about 50°F ( 10°C) and to be kept moist all the year round. Most growers regard them as curiosities, and they are not very common in collections.
Epiphytic Cacti By contrast, the epiphytes are grown in this country very commonly, many being sold as florists’ plants. In their native South American tropical rain forests, the epiphytic cacti are found growing in the
They need a good, porous soil and a compost of equal parts loam, peatmoss or leaf mold, decayed cow manure and sand, plus some charcoal is suitable. Leaf mold is ideal if it can be obtained as it more closely resembles the natural soil of the forests. The soilless composts are also very suitable for these and other cacti, but for the epiphytes, the lime-free type of compost is best. It helps to add a teaspoon of bonemeal to each pot of compost. Re-potting should be done annually. These cacti will survive winter temperatures as low as 41°F (5°C), but flower much better if kept a little warmer. They should be kept moist all the year round. In fact, it is best to forget that they are cacti and treat them as normal pot plants. When in bud, epiphytes can be fed every two weeks with a tomato-type potassium fertilizer.
Because these epiphytic cacti grow among trees, they do not need full sunlight. They make very successful house plants if grown on an east-facing window-ledge, where they will receive the early morning sun, but are in shade during the heat of the day. They grow rapidly, and when a plant outgrows a 6-in. pot, it should be re-started. A stem is cut from an epiphyllum, or a few segments from the schlumbergeras and rhipsalidopsis. The cutting is allowed to dry for two or three days, and then potted up. This drying period for cactus and other succulent cuttings is always carried out to prevent rot from spreading into the fleshy stems. As they are succulents, they do not wilt during this period as other plants would. The best time of the year for taking cuttings is April—May, although it is quite possible at any time during spring and summer.
Desert Cacti The desert cacti are the spiny tall or round plants that we associate with the American deserts. Actually many are found growing on rocky mountain sides and in grassy areas, as well as in the sandy regions of Mexico and South America. They all need the maximum amount of sunlight to flourish and flower freely. For this reason they do not make such good house plants as the epiphytes. If a greenhouse is not available, they should be kept on a south-facing window sill, and preferably stood outdoors from May to September.
A minimum winter temperature of 4.1°F (5°C) is adequate for most desert cacti. A well-drained compost is essential. One containing 2 parts loam, 2 parts peatmoss, 2 parts sand, 2 parts broken crocks, plus some charcoal and i pint bonemeal per bushel of mix, is suitable. Alternatively, a soilless compost may be used. Since the food content of the soil does not last forever, the plants should be repotted annually.
Many people seem to think that cacti need no water ! This is far from the truth, although they will certainly survive a period of dryness (after all they are adapted to do just this). This means that it is not necessary to worry too much while you are on vacation (although seedlings will suffer). But without water they will just survive, not grow, and the plants should be kept more or less continually moist between April and October. The watering should be reduced after this and they should be left dry during December and January, if kept in a greenhouse. Watering can be restarted gradually as the light improves in February. If the plants are wintered in a heated house with a very dry atmosphere, more water will be needed during winter to prevent excessive shrivelling. Indoors, the ideal winter spot is an unheated room, but this may not always be possible. The reason for keeping them dry at this time is that if they grow in the poor light of winter, they are likely to become distorted and may well rot the following year. Also, flowering is very much affected by the previous winter’s treatment.
Desert cacti are mostly very easily reproduced from cuttings. Some plants form offsets which can be removed and potted up, after the usual few days drying period. Some clustering plants will have rooted ‘pups’ (offsets) around the base of the parent; these can be ‘removed and potted up directly. If the plant does not form offsets, a section of stem can be cut off and potted up after drying for about a week. The base of the parent plant can be kept as it will often sprout again, forming a number of offsets around the cut top. The best time to do all this is, as before, between April and June.
As mentioned earlier, the other succulents fall into several different families, and since the cultivation varies somewhat for each, it is best to give a brief description of them. Crassulaceae This family is very large, consisting of leaf succulents with almost world-wide distribution. The most beautiful members of the family are the echeverias of the New World and the crassulas of South Africa. Other attractive plants are the aeoniums and sedums, with plump, often highly colored leaves, arranged in rosettes. All should be kept slightly moist all the year round. Seed of these plants is difficult to obtain, but they can mostly be easily reproduced from cuttings which need little or no drying before potting up. Some species can even be grown from leaves, just laid on the soil, when they will root, and send out new shoots.
Aizoaceae This is a family of leaf succulents found mainly in Africa. They vary from small shrubs to plants about r in. high consisting of one pair of very succulent leaves. One of the main characteristics of this group is that most of them have distinct resting periods, corresponding to the dry season of their native lands. During this period, from about October to March, they must be kept completely dry. The old leaves will gradually shrivel away. Watering should not be re-started until the new leaves appear in spring. Popular plants are the fall growing conophytums, glottiphyllums and pleiospilos and the summer growing lithops and faucarias. This group is quite easily raised from seed, or heads of clustering plants may be removed, dried for a few days and potted up. June to July is a good time for this.
This contains only one
Asclepiadaceae This family contains a large number of leafless stem succulents from the dry regions of the Old World. Where they occur, there are no bees and the flowers are pollinated by flies. To be attractive to flies, the flowers often have an unpleasant smell to us. However, the flowers are usually large (sometimes immense) in shades of reddish-brown or yellow, often covered with hairs. Stapelias are probably the best known in this group. We also have duvalias and carallumas. They are easily raised from seed, which germinates quickly but has a tendency to damp off equally quickly. Cuttings may be taken from June to August. They are best just laid on the soil and may be watered after about a week. Liliaceae This family contains not only the lily bulbs of our gardens but a group of leaf succulent plants which are found mainly on the African continent. The most interesting plants are the aloes, gasterias and haworthias.
Aloes can reach a large size and bear a superficial resemblance to the American agaves, with their long strap-like leaves. There are also a number of small plants which are very attractive and will survive on a window sill. Aloes have long flower stems, but the rosette does not die after flowering.
Gasterias and haworthias are found growing in the shade of grasses and small shrubs in their native land. This makes them useful small plants for growing on window sills or under the greenhouse staging.
All the plants which form clusters may be reproduced by removing offsets. Otherwise they must be raised from seed. Agavaceae This last family dealt with here, includes yuccas, sansevierias and agaves. It is the agaves that interest the grower of succulents. These are rosette-shaped plants with tough, strap-like leaves. Although many are far too large for the average grower, there are small species that are ideal for the living room, because the very tough leaves enable these plants to withstand the dry atmosphere. Many people are familiar with the large, rather coarse specimens of Agave americana found growing along the Mediterranean coast. These plants have at some time been introduced; the agaves are native to the southern U.S.A., Mexico, Central America, the West Indies, and northern South America.
Agave flowers are borne on stems many feet long, but only on very old specimens, and after flowering, the rosette dies, but by then there are usually offsets growing around the base of the plant. These can be removed and used for propagation. Agaves are very easily raised from seed.
Cultivation The cultivation of the other succulents is very similar to that of the desert cacti; any differences have been mentioned. They should be given plenty of water in summer and kept either dry or slightly moist in winter, depending on where they are kept. A suitable compost is that recommended for a Desert Cacti, with the exception of the Aizoaceae which are better with rather more grit, up to 50%. They all need the maximum amount of sunlight, particularly the Aizoaceae, which are not really suitable as Muse plants, but need the sunniest part of the greenhouse. A minimum winter temperature of 41°F (5°C) is adequate for most succulents although the stapelias and other Asclepiadaceae appreciate a little more.
Raising from seed Cacti and other succulents can be raised from seed in much the same manner as any other greenhouse plants. A good seed compost should be used; either a standard or soilless. After thoroughly moistening the compost, the seeds are just scattered on the surface. The container is placed in a plastic bag to conserve moisture. A temperature of 7o°-8o°F (21°-27`C) is needed for germination. If a propagator is available, early spring is the best time to sow, otherwise it is necessary to wait until later when the weather warms up.
Pests and diseases Cacti and other succuments do not suffer greatly from these, if they are carefully looked after. Small cotton-wool-like patches indicate mealy bugs which can be controlled with a malathion spray (but do not use malathion on Crassulaceae). Brown spots on stems (particularly epiphyllums) are usually due to too low winter temperatures, too much nitrogen in the compost, or otherwise faulty cultivation. Cold, damp conditions can cause plants to rot.
Cacti and Other Succulents
Chamaecereus silvestri (peanut cactus) is found growing among grass and low bushes in Western Argentina. The short, prostrate stems are freely branching, and covered with short, stiff white spines. The stems are pale green in winter, but turn violet in the hot sun. The furry brown buds open in May or June to large scarlet flowers. This cactus is hardy if kept dry, and may be wintered in an unheated cold frame in milder areas. Propagation is particularly easy by removing branches and rooting them.
Cleistocactus strausii from Bolivia, forms a tall, silvery column, which may reach a height of 5 ft. With age it branches from the base. The stems are covered with short white spines. Old specimens will flower; the narrow flowers are red and are formed at the top of the stem. However, if confined to a pot it will be many years before this plant becomes too large.
Echinocactus grusonii (golden barrel cactus) comes from the deserts of central Mexico. Young seedlings have tubercles which carry stout golden spines. As the plant gets larger the tubercles merge into ribs. Mature specimens of this cactus are about a yard across, but are very ancient as it takes about ten years for a specimen in cultivation to make a diameter of 6 in. The small yellow flowers are seldom produced under home conditions due to poor light intensity. Echinocereus knippelianus is native to Mexico. The dark green, almost globular stem is about 2 in. across. It is divided by five ribs which carry weak, white spines. The pink flowers are produced profusely in May. This is a slow-growing plant and should be watered with care. Like most echinocereus, it is hardy in mild areas of the country if kept dry.
Echinocereus pectinatus is found growing in central Mexico. It has a thick stem about 3 in. in diameter, branching from the base, and covered very neatly with short white spines, arranged in a comb-like pattern. The pink flowers are 3-4 in. across and in some specimens are sweetly scented. The flowering period is about June. This is a slow growing cactus which is hardy in winter where winters are less severe if kept dry; it needs particularly good drainage. Echinopsis rhodotricha from Argentina, is an oval plant which in the wild can reach a height of 32 in. In cultivation it will flower when 6 in. high; the long-tubed, white fragrant flowers are about 6 in. long and 3 in. across. They are produced freely during the summer. They open in the evening. The stem is dark green, divided into ribs with stout brown spines. This is a fast growing plant and is hardy where winters are milder if kept dry. The best known is E. eyrieseii, but most specimens on the market are probably hybrids.
Echinopsis ‘Golden Dream’ is a Lobivia x Echinopsis hybrid, a vigorous and hardy plant. It has a globular plant body, up to 6 in. across, divided into ribs with short brownish spines. Offsets form around the base. The golden-yellow flowers appear in summer; they have long tubes and are 2 to 3 in. across and slightly scented.
Epiphyllum hybrids are examples of the `jungle’ type of cactus. They make largish plants with strap-like stems, often 2 or 3 ft. long. The flowers are 3 or 4 in. across, and appear on the edges of the stems, usually opening in the evening. Various un-named red hybrids are common; among the named specimens are ‘Appeal’ (red), ‘Bliss) (orange), `Cooperi’ (white and scented), `Exotique’ (purplish), ‘Gloria’ (orange-red) and ‘Sunburst’ (orange).
Ferocactus acanthodes from southern California makes a cylindrical plant about 9 ft. high and 3 ft. across in nature. But such plants are very old. Seedlings and young plants make delightful pot plants; they are globular and have bright red spines, but are unlikely to reach flowering size in cultivation. The flowers, when produced are yellow and small for such a large plant, about 2 in. across.
Gymnocalycium bruchii is a miniature cactus from Argentina which eventually clusters from the base. The globular plant body is divided by twelve ribs, bearing neat white spines, covering the plant. The pale pink flowers open in May; these are over i in. long, and since the flowering plant may be less than i in. across, it often cannot be seen for flowers. This is a very easy plant to grow and flower.
Gymnocalycium baldianum is sometimes incorrectly named as G. venturianum. This native of Uruguay forms a plant body 3 in. across; it has nine ribs with yellowish spines. Old specimens form offsets. The flowers, produced in May, are usually deep red but occasionally specimens are found with beautiful intense pink flowers.
Gymnocalycium platense, a native of Argentina, is a globular plant, eventually 3 in. or more in diameter. The plant body is grayish-green and is divided into twelve or fourteen ribs. These carry short whitish spines. White flowers are freely produced in early summer. This is a very hardy, easily grown plant.
Hamatocactus setispinus is native to Mexico and southern Texas. It is a globular plant which can be as much as 5 in. across. Very old specimens cluster from the base. The stem is dark green and divided into thirteen ribs. The large satiny flowers are borne on top of the plant continuously through the summer. The petals are deep yellow with a red base. Again a very easy plant to grow and flower.
Lobivia jajoiana grows in Argentina at altitudes of up to 10,000 ft. It is a cylindrical cactus, slow-growing, 2 or 3 in. thick forming a few offsets. The plant body is dark
Mammillaria craigii is a native of Mexico. It is a globular plant, branching with age. Like all mammillarias, the plant body is covered with small protuberances (tubercles). These have yellowish-brown spines on their tips. The small, deep pink bell-like flowers form a circle around the top of the plant in spring.
Mammillaria spinosissima is a Mexican plant. It is very variable; the spines may be white, yellow, brown or red. One of the most attractive forms is the variety sanguinea, with red-tipped spines. The cylindrical stem is dark green; it may remain solitary, or cluster. The purplish-red flowers open during the summer, and may be followed by bright red berries.
Mammillaria prolifera is a widely distributed cactus, found in Texas, the West Indies and Mexico. It clusters freely, forming a ‘cushion’ of small heads about 1 in. across, covered with fine white spines. Creamy flowers appear in late spring and are often followed by orange-red berries, which are said to taste like strawberries. The heads are knocked off very easily, so the plant must be handled carefully.
Notocactus haselbergii grows wild in southern Brazil. It forms a silvery ball, about 4 in. across, covered with fine white spines. The tomato-red flowers are carried on top of the plant in early summer. This is a hardy cactus, easy to grow, but does not flower as a seedling. Flowering-size plants are about 21in. across.
Notocactus mammulosus, a native of Uruguay and Argentina, forms a large, globular plant, with stout yellowish spines. With age it forms offsets from the base. White, woolly buds appear at the top of the plant and open to golden-yellow flowers in early summer. It flowers profusely and will put up with cool conditions. The flowers are self-fertile and large quantities of dark brown seeds are formed.
Opuntia microdasys is a Mexican plant, and to keep it unmarked, the winter temperature should be at least 45°F (7°C). It has flat stem segments (or pads) up to about 6 in. long. These are dotted with little collections of fine barbed hairs (glochids), which may be white, yellow or dark reddish-brown, depending on the variety. These glochids (characteristic of the opuntias) can irritate the skin. This cactus is grown for the beauty of its form and rarely flowers as a pot-plant. Given a free root run in a greenhouse bed, it produces yellow flowers in May.
Opuntia basilaris spreads from northern Mexico to the southern U.S.A. It has pads about 8 in. long of a beautiful bluish color, dotted with collections of dark brown glochids. Branches form from the base, producing a large clump. The flowers are red, but it rarely flowers as a pot plant. There is a particularly beautiful variety, cordata, with
Rebutia calliantha var. Krainziana is an example of the compact, very free-flowering South American rebutias. It will bloom when only t in. across. The globular stems are dark green, neatly covered with short white spines. The large orange flowers are produced in rings around the base of the plant in May. This is one of the easiest of the small cacti to flower and quite an old plant will only fill a 4-in. pot, but will be covered with flowers.
Rebutia miniscula var. violaciflora, from Argentina, is found growing about 10,000 ft. above sea level. It is a small clustering plant, and will flower when about t in. across. It is a light green in color with short ginger spines. The intense magenta pink flowers are produced from the base of the plant in April and May. They are self-fertile, and if left undisturbed, the plant will eventually be surrounded by dozens of little self-sown seedlings.
Rhipsalidopsis rosea is an epiphyte from the forests of southern Brazil. It is a small shrub about 9 in. high, consisting of dozens of stem segments about r in. long, with short bristles at the ends. The stems vary from green to dark red. The pale pink, bell-shaped flowers, about t in. across, cover the plant during May. After flowering the plant will look shrivelled, but after a few weeks it will come into growth again.
Schlumbergera `Konigers Weihnachtsfreude’ is one of the many schlumbergera hybrids flowering in the winter which are often called Christmas cactus. It is an epiphyte and forms a shrub, becoming pendent with age, and can reach massive proportions if not broken up and re-started. The glossy green stem segments are up to about
Other Succulent Plants
Aeonium domesticum (Crassulaceae) The aeoniums are native to the Canary Islands and are almost hardy. Beautiful specimens of these small shrubs may be found in dry warm areas of the country. A. domesticum has almost circular leaves covered with fine hairs; the yellow flowers are produced in summer. Aeoniums may be grown permanently as pot plants or planted out in a rock garden for the summer, and repotted and stored under the greenhouse staging in winter.
Agave filifera (Agavaceae), a native of Mexico, is one of the smaller growing agaves suitable for pot cultivation. It forms a rosette about 2 ft. across, consisting of long, narrow dark green leaves, with white threads along the edges. Agaves only flower when old, and the flowering rosette dies. But new ones are formed at the base of the old plant. The flower stem is over 6 ft. high and the flowers are greenish.
Agave parviflora (Agavaceae) is a rare plant in the wild, found in a few localities in southern Arizona and Mexico only. It forms a rosette about 8 in. in diameter, ideal for a pot plant. The dark green leaves have white markings and marginal threads. The flower spike is about 3 ft. high and the flowers are reddish. New rosettes are formed at the base of the old plant after flowering.
Aloe jucunda (Liliaceae) is a miniature aloe, native to Somalia. The small, flat rosettes are about 4 in. across and the bright green leaves have attractive white spots, and small teeth along their edges. The pink flowers, carried on a long stem, open in spring. This aloe clusters freely and the vidual heads can be used to start new plants.
Aloe variegata (Liliaceae) (partridge-breasted aloe) a native of Cape Province, South Africa, forms a stemless rosette, about ft. high; the dark green leaves have attractive white markings. The plant produces many offsets which are attached to the parent plant by underground stems. The small, orange, bell-shaped flowers are carried on a stout stem in March.
Caralluma europaea (Asclepiadaceae) is found around part of the Mediterranean coast, and also in South Africa. The thick leafless stems are grayish-green. This is a summer growing plant and the tiny flowers are stemless and produced in clusters. They are yellowish with brownish markings. The seeds are carried in long horn-shaped pods.
Conophytum flavum (Aizoaceae) comes from South Africa. The small plant bodies are green and rounded, freely clustering. The bright yellow flowers are usually produced in September or October, when they open in the afternoon. The plant should be watered when the old leaves have shrivelled, usually about August, and watering should be continued until November.
Conophytum salmonicolor (Aizoaceae) is a native of Namaqualand, South Africa. The green plant body is about in. high
Crassula falcata (Crassulaceae) spreads from Cape Province to Natal in South Africa. Because of its striking red flowers, it is a popular florist’s plant. Ix is large, growing to about t ft., with bluish-gray leaves. The scarlet flowers are carried on a stout stem. It can be propagated from leaf cuttings.
Crassula teres (Crassulaceae) is a miniature plant from South-West Africa. The broad leaves are closely packed around the stem to form a short column. With age the plant clusters to form attractive groups. The tiny white flowers are stemless. It should be grown in a very open compost, placed in a sunny position and not over watered.
Duvalia radiata (Asclepiadaceae) is a smallish plant from Africa. The short, thick stem are prostrate and without leaves. The reddish-brown flowers are small and fleshy, but the horn-shaped seed pods are large and packed with numerous seeds, attached to tiny ‘parachutes’. The growing and flowering period is summer.
Echeveria derenbergii (Crassulaceae) (the painted lady) is a dwarf plant from Mexico. It forms an almost stemless rosette about 3 in. across, which is soon surrounded by numerous off-sets. The leaves are plump and pale green with a white waxy coating. The reddish-yellow flowers open in the spring.
Echeveria hoveyi (Crassulaceae) from Mexico, forms a short-stemmed loose rosette which soon produces side shoots, making an attractive cluster. The long leaves are gray-green with pink and cream stripes. The coloring varies with the seasons; it is at its
Euphorbia aggregata (Euphorbiaceae) from Cape Province, is a shrub about i ft. high. It is a freely branching plant which soon clusters. The leafless stems are over in. thick. The insignificant flowers are carried on thorn-like stalks which persist long after the flowers have died. This gives the whole plant a ‘spiny’ appearance, rather like a clustering cactus. The growing period is summer.
Euphorbia beaumieriana (Euphorbiaceae) comes from Morocco, where it can reach a height of 6 ft. It is, however much smaller in pots in collections. It is a cactus-like plant with ribs and spines. Like all euphorbias, it has milky sap, painful or even dangerous in the mouth or eyes.