The Purslane Family

This is another Family of the Order Caryophyllales. and all its members are more or less succulent. However, many are small-flowered annuals and of interest only to the botanist. Of the 19 genera, about seven are represented in succulent collections. All are leaf succulents. although with a frequent tendency to the caudiciform in Anacampseros (A. alstonii, 21.22). Talinum (T. caffrum. T. guadalupense. 15.4) and some Portu-lacas. The leaves are always entire and often bear at the base long white hairs that are interpreted as modified stipules. An extreme development of the stipules is noted under/lnacampserosbelow. Among the generally small flowers are a few more showy ones, and it is these that have caught the eye of the horticulturist and earned the bearers a place in our gardens. Typically there are two fleshy green sepals, five (sometimes four or six) free petals and one. two or more whorls of stamens, the largest flowers (Portulaca. Lewisia) having most stamens. The ovary has three (or up to five) united carpels.

Below (12 1) Portulaca grandiflora rivals Dorotheanthus (11 101 as the most colourful and popular annual succulent Note the equally wide range ol llower colours

Portulaca is a widespread and prolific genus, although the present tendency is to reduce its 125 described species to about 15. Some are annual, some perennial. One scarcely succulent species, the common purslane, P. oleracea. has a long historyasa potherb.and has been carried from country to country. It was probably native to India but is now a cosmopolitan weed. Gerard (1598) says of it: "It cooleth an hot stomack". P. grandiflora (5.3. 12.1) is an admirable half-hardy annual that brings colour to the drier, poorer parts of a garden. It has been subject to intensive selection for colour variants and double flowers, and its genetical background has been worked out in detail (see page 65).

Ceraria (12.2) and Portulacaria are closely related genera of tender, perennial species that grow into large shrubs in nature, although in cultivation they are more familiar as tiny plants, their thick, rather fleshy stems giving them, when young, an attractive bonsai appearance. The leaves are small, simple, fleshy and flat to nearly cylindrical. The flowers are minute and hardly ever seen in cultivation. The variegated form of Portulacaria afra. with yellow patches on the foliage, is justly popular.

Lewisia is most in favour among rock and alpine gardeners, but no true lover of succulents should overlook it. It comprises about 16 species from the western USA through Mexico to Bolivia. Typically there is a stout perennial rootstock that can endure long desiccation and bears a rosette of flattened or cylindrical fleshy leaves that are evergreen in some species, deciduous in others. Most of the kinds offered by florists are of hybrid origin, and the pedigrees are largely conjectural. The flowers, mostly in shades of pink and apricot, are quite showy (12.4,7). Despite their hardiness, Lewisias are sensitive to waterlogging, and the protection of a frame or alpine house is recommended. Propagation is by dividing up clumps or

Right (12.2) Ceraria namaquensis. perfect as a Oonsai plant but a tall scarcely succulent shrub in old age Judicious pruning each autumn will keep the plant bushy

Below right (12 3) Anacampseros papyracea. The white scales are stipules enveloping minute green leaves beneath The Ilowers expand lor an hour or two only. The pot is 7cm (2\in) wide Overleaf! 12.4): Although Lewisias are hardy, they mostly do better with the protection of a frame or unhealed alpine house in winter. These are hybrids ol L. cotyledon.

THE PURSLANE FAMILY (PORTULACACEAE)-A breakdown to genus level (succulent members)

Capsule dehiscing by a lid or valves splitting from the base upwards; ovules more

Capsule dehiscing by valves splitting from the top downwards; ovules mor than 6

Calandr

raising seed. Lewisia rediviva is the State flower of Montana, called bitter-root by allusion to the bitter taste of the bark, which is stripped off by the Indians before they boil the root as food. It first came to the notice of botanists when a herbarium specimen came to life after some years and. on being potted and watered, flowered and revealed itself as a

Calandrinia and Talinum are among the genera of which isolated species occasionally find their way into the glasshouses of succulent enthusiasts, but are usually soon ushered out again because the flowers are so inconspicuous or the seed comes up everywhere. C. grandiflora and some allied species are grown as border annuals: the blue-grey glaucous foliage is somewhat fleshy and pleasantly sets off the purple-magenta flowers.

This leaves Anacampseros. a fascinating and highly evolved genus of succulent xerophytes offering much to the seeker after the unusual. About half of the 50 or so described species are very easy to grow: they thrive in full sun and a porous soil, with ample water in summer and frost exclusion in winter, and they show their appreciation by seeding themselves everywhere. They are all small enough to accommodate in 7-9cm (3-3Hin) pots. The leaves are more or less flattened, very fleshy, simple and rosetted, usually with silky hairs at the base clothing the stems. The pink (or rarely white) flowers are held high in inflorescences. A. rufescens is a common example of this kind; A. telephiastrum is larger in all its parts. Very different are those species in which the leaves are minute and completely enveloped by large, white, papery stipules (12.3). Here, presumably, we have another device associated with water conservation and reducing the light intensity reaching the chlorophyll: the plant grows its own sunshades. Certainly the plants are intense xerophytes, occurring in full sunshine on exposed flat places in South Africa as well as in rock crevices, usually associated with the quartz rock with which their white shoots blend and are difficult to see.

Contrary to what one might expect, the small-leaved species of Anacampseros seem to like as much water as those with large leaves in cultivation: it is a mistake to keep them too dry. The soil should be very porous and a winter minimum of 7°C (45°F) is advisable. The flowers are solitary at the stem tips and it is quite an occasion to see one open at all (12.5). Mostly they ripen capsules of seed without opening (4.17)—an example of cleistogamy.

The stem-succulent Portulacaceae are dealt with in Chapter 15, and thecaudici-form species in Chapter 21.

Above (12.5): Flower ol Anacampseros bremekampii showing the six red petals, eight stamens and three styles, readily distinguishable from the isomerous flower of Crassulaceae (page 31) Right(12.6): Anacampseros albissima from Namaqualand and South West Africa in a 6cm(2Viin) pot Each papery white scale on the stem conceals a tiny green leaf

Below (12.7): Lewisia hybrids in the author's garden. The natural clay soil has been lightened with grit and peal and the plants are set among light-reflecting rocks

With the lily Family we come to the first of the Orders of Monocotyledons. It is regarded as a key Order, the structurally simple flowers and fruits standing near the start of the ancestral line from which evolved more specialized groups: the grasses, bromeliads and orchids. The Liliaceae cover an estimated 250 genera and 3.700 species. The distribution is cosmopolitan, although it is usual to find each of the 28 Tribes into which it is divided confined more or less to one area or continent. Distinguishing featuresare a radially symmetrical flower with a perianth composed of six similar members without a distinction into green calyx and coloured corolla. Stamens also number six and carpels three: the ovary is never inferior.

Minor tribes

The Liliaceae provide our gardens with many fine flowers besides lilies, particularly in spring and early summer, including tulips and hyacinths and many bulbous genera: the Family also includes such vegetables as onions and aspa ragus. Some species of Asparagus are extreme xerophytes and grow alongside euphorbias and the Stapelieae in South Africa. One species I collected in the Lebombo Mountains, in pachypodium territory, has fat watery underground tubers and is as good an example of root succulence as I know. Bulbs are also well adapted to store food underground and endure long seasons unfavourable for growth. Whether or not some desert bulbs qualify as succulents is long disputed. It is very much a matter of taste whether or not you extend your collection to include Scilla violacea, Ornithogalum caudalum, Drimia. Buphane. Haemanthusand many more. Bowiea volubilis (page 158) has long been accepted by succulent growers: if planted above ground the large spherical bulb turns green and never produces anything nearer a leaf than a few "blades of grass". Instead it sprouts a long twining annual shoot with finely divided side branches and small greenish flowers that set abundant seed —altogether an oddity, of novelty value in a mixed collection. A recendy described curiosity from near Steinkopf is Albuca unifoliata (page 158), in which we have the ultimate economy: a single, club-shaped, very fleshy leaf one year, and a flower stalk and three to five small starry blooms the next, but never both together. I have had bulbs rest for two years, and in habitat they may well remain dormant for even longer, awaiting sufficient rain to stir them into activity. Lachenalia patula is rather similar, and no more amenable to cultivation.

Another manifestation of succulence in Liliaceae is in the genus Bulbine, most of whose many species have pale green, somewhat fleshy leaves. It is widely spread over South and East Africa, but only a few species are at all common in cultivation. The starry flowers borne in long racemes are mostly yellow, but in B. frutescens there is an orange cultivar, 'Hallmark', and a white one, 'Virgo'. The spot character for recognizing Bulbine is the presence of shaggy hair on the filaments of the stamens. B. latifolia has rosettes of soft, aloe-like leaves borne on a short thick stem, and flowers over a long season. More for c the dwarf tuberous species that die down for a part of the year; these need strict observation of the resting period or they will quickly fade away. B. succulenla (13.1) is one such, with a subterranean caudex crowned by bristlesand producing two to four erect, very soft and watery grooved leaves. In habitat these remain short, but in cultivation all the dwarf species lose character completely and the leaves become much longer and thinner. Highly prized is B. mesembryanthoides, with one or two squat watery leaves with truncated translucent tips—a true "window plant". Strangest of all is B. haworthioides, which looks like a miniature Haworlhia tessellata. It was found as recently as 1962 and at that time was considered rare, but on a search in 1971 populations came to light so dense that the plants almost touched one another.

Aloineae

The fourth Tribe to be considered is Aloineae, composed wholly of succulents. It is allied to the Kniphofieae, which include Kniphofia, the redhot poker of our gardens, hardier and non-succulent. Aloineae are perennial rosette plants, solitary in some species, suckering in others to form clumps, and occasionally tree-like with a thick but curiously spongy

Overleaf (13.2]: Aloe shrubs and trees are a memorable feature of the African landscape Here the widespread Aloe arborescens is seen at the mouth of Storms River, South Cape

Below (13.3): Aloe thompsoniae represents a small but interesting group of "grass aloes ", seen here in habitat in North East Transvaal. It Is a parent of the hybrid Bountiful'.

Aloe Lebombo

trunk. The inflorescence arises laterally, so that the rosette bearing it does not die after flowering, as it does in agave, and the flowers are borne in racemes or panicles. The fruit is a dry. three-celled capsule, except in one Madagascan section of the genus Aloe (Lomato-phyllum), where it is a fleshy berry. All are predominantly South African, Aloe alone extending the range to Madagascar, Arabia and some Atlantic islands.

Aloe is the largest and earliest described genus, which at one time included all the species. As monographed by Reynolds (1950, 1966) it now includes 359 species — or more, if the small segregate genera are also included. The smallest,/). (Leptaloe)saundersiae, hasa rosette of grass-like leaves lying flat on the soil and barely 10cm (4in) across; the largest is probably A. bainesii, a tree of massive bulk and singularappearance up to 20m(67ft) tall-among the largest of Monocotyledons. A. dichotoma (3.3,13.4) is almost as large. They do not form solid wood like Dicotyledons: a cross-section of the stem is like a dense aggregation of fibres with barely a hint of annual rings, so that the age of large specimens can only be guessed. Although very light, the wood must be extremely strong to support the crown of water-filled branches. The bark is smooth and leathery and flakes off in plates. A few aloes such as A. ciliaris have long, weak, scrambling stems.

Aloe leaves are arranged spirally in terminal rosettes (13.7), or rarely distichous (in two series), an example being A. plicatilis. In species where the stems elongate there are sometimes scattered leaves along the axis too (13.2). Leaves may be triangular or parallel-sided, plain or variously striped and spotted, flat or channelled and entire or prickly along the margins. When cut they exude a sticky, bitter sap containing aloin, the source of medicinal aloes. The flowers are tubular and pendant, and come in shades of red, orange and yellow or rarely white (13.6. 10). Sunbirds and bees are the principal pollinators, and copious nectar is offered to them (4.4). The inflorescence is a simple raceme, a spike or a panicle.

The genus has much to offer collectors, although many of the species eventually outgrow the space available in an amateur glasshouse. However, even these are worth having for the beauty of the seedlings. In frost-free countries where aloes can be grown in the open, a collection of species is a noble sight, and in South Africa they are popular garden subjects, being largely trouble-free, floriferous and tolerant of drought. New hybrids are continually being named and introduced, with even greater vigour and profusion of flowers. In Europe hybridization is also popular, but it is the dwarf species that are most in demand. A few of these have long been popular as house plants— A. variegata, the 'Partridge Aloe', for instance. A. aristata (13.9) resembles a Hauiorthia in leaf form and is the hardiest of the genus. Collectors' pieces are the Madagascan miniatures A. haworthioides and A. descoingsti (13.5). A. (Guillaumi-nia) albiflora, with bell-shaped white flowers, isalsoappealing. Needing special

Right ( 13 4): A one ol the larger true aloes, is the involuntary host here lor nests ol the sociable weaver bird.

Below (13.5): Aloe descoingsii /s a native ol Madagascar and recalls Haworthia in habit. II is one ol the smallest aloes (this particular clump is about 8cm (3%in) across) and requires warmth and cautious watering

care are the so-called "grass aloes" with long, narrow deciduous grassy leaves (13.3). Some even form a bulb at the base: A. kniphofioides. for example. Water must be withheld after flowering, and the plant allowed to die down; it will usually give the first sign itself when water is again needed, by sending up new green leaves.

No succulents are easier to cross than aloes. They tend to be self-incompatible, and hybrids can be made not only within the genus but with other Aloineae, for example Aloe XGasteria (= X Castro-lea). Some of the progeny can be real improvements, such as the free-flowering 'Bountiful' (A. albiflora X thompsoniae 13.3) and 'Sabra' (A. albiflora X bella-tula).

'American Aloe', it should be noted, isa misnomer for agave.

Gasteria consists of dwarf, almost or quite stemless succulents with rosettes similar to Aloe but showing more tendency for the leaves to remain in two series (13.8). They all start that way: in some species they become spiral with age. in others they do not. Unlike those of Aloe, the leaves are never prickly, although they may be covered in white papillae (G. verrucosa), or rough with small green and white pustules (G. batesiana). The shape is parallel-sided and rounded at the tip with a small, sharp, white point; some are flat, others grooved or V-shaped in cross-section. The racemes are usually unbranched, and the most noticeable feature of the flowers is the swollen base of the perianth tube, which gives the genus its name (gaster = a belly). The colour is pink, with the lobes lighter or greenish at the tip. The genus is confined to South and South West Africa.

Jacobsen (1975) lists 76 species, but they are mostly ill-defined and the number will certainly be reduced when we know more about their variability in the field. Different names have been applied to young and mature shoots of the same species! Horticulturally, they are all attractive, unassuming, undemanding plants with great variety in the shapes and markings of the leaves, which are often splashed or spotted with paler patches. In addition to those mentioned above, G. pulchra and G. liliputana form clusters of neat rosettes and flower freely in summer. But the gem among the miniatures is G. armstrongii, with usually a single, slow-growing rosette of fat, blackish green tongue-like leaves in two series like the pages of a book. By way of colour contrast, there are some fine variegated gasterias.

Right (13.6): The smaller aloes are dependable lor llowers. undemanding and generally long lived in collections. This one is Aloe inyangensis Irom Rhodesia.

The genus exhibits in varying degrees the phenomenon of juvenile and adult phases, the habit of the plant changingas it matures. The most dramatic example is G. beckeri, in which the young rosette looks much like G. armstrongii but abruptly goes over to the adult phase of spirally arranged, smooth, obliquely V-shaped foliage with yellow spots. So different are the two phases that one would never associate them as the same species if seen separately. G. beckeri flowers only from the adult growths. In G. armstrongii the juvenile phase is retained and flowers without changing to adult leaves. We call this type of arrested juvenility neoteny. a term borrowed from zoology.

Gasteria forms interesting hybrids with both Aloe and Haworthia.

Haworthia enjoys great popularity among collectors of succulents, some of whom specialize in the genus and bring together all the myriad variations of leaf shape and form, colour and texture, of which 13.11, 12 give but a small idea. There are 68 species recognized in the latest monograph by Bayer (1976), with 41 subspecies, varieties or forms.

Haworthias are compact-growing solitary or clumping plants with tight rosettes close to the soil level. A few form a very short stem with age, covered in spirally arranged leaves sometimes set in three rows. In some species the leaves are very firm and tough, usually dark green in colour and commonly set with white pustules, tubercles or ridges; in others they are soft and pale green, often with translucent lines or patches at the tip ("windows" 2.6). which sometimes bears a white bristle. In nature, haworthias seek out the shade of rocks and shrubs, often hiding completely from view, and to photograph some species it is necessary to clear away the undergrowth in order to reveal the plant at all. The fleshy, long roots have a fibrous core that, by shrinkage, draws the rosette down into the soil, especially during drought, when it may become partly covered in windblown sand. We call such roots contractile.

The flowers of Haworthia are borne in rather slender, rarely branched, racemes and there is little variation throughout the genus. The perianth members are off-white with darker veins. The distinction from all the other Aloineae lies in the mouth of the perianth, which is obliquely flared—a rare example of zygomorphy in

Top left (13.7): A rare endemic from the mountains ot western Lesotho. Aloe polyphylla, the "spiral aloe" is much in demand by collectors The spiralling shows up

Lett (13.8): A typical Gasteria (G. maculata) showing the alternate, entire, spotted leaves arranged in two series Gasterias tolerate shade better than most succulents

Succulent Plant With Dried Stipule

the Liliaceae. One section of the genus has a regular (rather than zygomorphic) perianth, and for that reason is sometimes segregated as a separate genus. Astro-loba. Even more distinctive is the species H. (Poellnitzia) rubriflora. with erect, tubular, red flowers adapted to bird pollination.

The range of the genus is over the drier parts of South and South West Africa. As with many genera beloved of collectors, all the species are deemed worthy of growing and each addict has his own favourites. Here I shall merely mention some of the extremes of evolutionary development. In one direction we have the formation of an underground bulb with grass-like leaves: H. graminifolia (7.7) is the halfway stage and H. (Chor-tolirion) angolensis has a fully formed bulb. A parallel development was noted in Aloe. Even more bizarre are H. maughanii and H. truncata (13.12), whose windowed leaves in flat spirals or two rows look exactly as if freshly cut level with the soil with a knife. They are difficult to find and fascinating to study in habitat, and are always a magnet to lovers of unusual plants.

Cultivation

Of all succulents, Aloineae tolerate shade best, and as a result are usually consigned to the darker corners of a glasshouse — under the staging, for instance, where little else can flourish except spiders and woodlice. This is a pity, because, although they tolerate the indignity, a little sun colours up the leaves beautifully, and haworthias, in particular, need to be viewed at eye level for the full beauty of their leaf rosettes to be appreciated (6.16). Also, like all leaf succulents, they need regular attention to keep them tidy by removal of withered and discoloured leaves. High temperatures are not needed; indeed, even the tropical African aloes seem none the worse for a winter minimum of 5°C (40°F). Most are adaptable to a routine of summer watering, with the exception of the "grass aloes", where one lets the plant indicate when it wants to grow. A few aloes with very thick stems, such as A. bngislyla. I find extra susceptible to black rot if overwatered.

Outside the Aloineae, Bowiea is no trouble, nor are the larger growing bulb-ines, but the dwarf deciduous sorts are not recommended to beginners. Again strict observance of the dry season is the

Top right (13.9): Aloe aristata. the only hardy aloe, has enjoyed long popularity since its introduction into cultivation in 1700. The rosette rarely needs a large pot and blooms readily.

Right (13.10): Superlicially all alike, aloe flowers bear closer study and show much variation in lorm and colour. These are the 3.5cm (Win) blooms ol Aloe compressa.

Haworthia Maughanii Sowing

All succulent Liliaceae can be raised from seed, some very readily, although it must be remembered that seed from one's own plants may well be hybrid if no precautions were taken to isolate the plant from other species at the time of flowering. The larger aloes make especially attractive seedlings even if one has to dispose of them when they get too big. Vegetative propagation by suckers and cuttings is practicable for most. Gasterias and the soft-leaved haworthias mostly root from single leaves and eventually regenerate new plants, and Bowiea can be raised from single bulb scales if they are removed and stuck in sand and peat like normal cuttings.

Left (13.11] Haworthia fasciata. with white in-crusted bands Haworthias owe their popularity to their compact growth, shade tolerance, and diversity ot leal form and marking. The flowers

Building Your Own Greenhouse

Building Your Own Greenhouse

You Might Just End Up Spending More Time In Planning Your Greenhouse Than Your Home Don’t Blame Us If Your Wife Gets Mad. Don't Be A Conventional Greenhouse Dreamer! Come Out Of The Mould, Build Your Own And Let Your Greenhouse Give A Better Yield Than Any Other In Town! Discover How You Can Start Your Own Greenhouse With Healthier Plants… Anytime Of The Year!

Get My Free Ebook


Post a comment