Euphorbia

The Euphorbiuceue, in spite of the superficial resemblance of some species to members of the Cereanae and other cactus genera, is clearly distinguishable by the presence of a milky-white fluid which exudes from the damaged portions of the stems. It is a very variable family and includes our own common spurges as well as the well-known poinsettia (Euphorbia pulcherrima). Crotons too are members of the same overall family.

The flowers of euphorbia are really extremely small, the more important feature being the bracts or cyathophylls which are often brightly coloured as with the poinset-tias and E. splendens. Succulent varieties of euphorbia in spite of the similarity of their flowering parts produce few or no leaves, those that arc produced frequently falling during the first winter. The main exception to this rule is the crown of thorns and related species. The cactus-like varieties are particularly well suited to centrally heated living rooms since they do not require the same dry cool atmosphere during winter as do the true upright cacti. They are also very much faster growing and rapidly reach the stage at which they look to the uninitiated precisely like the columnar branching cacti.

Propagation can be carried out by seed, in which case it is advisable to surround the young capsules with a paper bag as the seed is frequently ejected with great force when mature, or by cuttings. In the latter case the fresh cutting material should be rubbed in powdered charcoal as soon as it is cut and allowed to dry out for a day or two before insertion. If charcoal is not available it is are normally much shorter. These fall off as the stems grow older, normally during the first winter. The flowers are produced at the tips of the spreading branches and the old flower stems remain even after the flowers have died. There are also attractive cristate forms of this variety.

Propagation is normally done by seed as stem cuttings lend to grow in a somewhat one-sided fashion never making a proper head of stems as the I rue species does. When buying a plant look for signs of this all-round growth. Winter temperatures should be slightly higher than for most other succulents and it may be advisable to bring the plant indoors during the cold period : this warmer environment should be accompanied by a little more water to prevent shrivelling.

Euphorbia (com inued)

The group of euphorbias on this page could all be mistaken for spineless barrel-type cacti such as Asirophyium. They differ, of course, in having the milky sap so typical of the euphorbias. They are all quite difficult to obtain and are relatively uncommon in cultivation, one reason being that they have to be raised from seed and, as explained varieties, notably Euphorbia obesa.

Euphorbia meloformis is one of the more common sorts and makes a neat hemispherical plant, usually single but occasionally forming clumps from the base in its native habitat in Cape Province although I have never seen this happen in cultivation. It tends to have a somewhat flattened appearance being generally broader than high and can ultimately attain a size of about 4 in (10 cm). The root, as in the other globular Euphorbia species, is thick and turnip like and the mid-green stems have between eight and twelve ribs which are normally vertical but may occasionally be twisted slightly to form a gradual spiral. As mentioned earlier, the top is very much flattened and looks just as though someone had stepped on it. The sides of the ribs arc banded obliquely and slightly furrowed and the old leaf cushions give the appearance of miniature areoles but lack the felting of wool which is peculiar to the true areoles of cacti. The leaves are very small and produced for a short time only at the growing lip of the plant, falling off before they have a chance to reach the sides. The flowers are fairly freely produced even on quite young 166 plants and the old stems, which are re peatedly brancned. remain even after the flowers have fallen and give the plant a slightly spiny appearance.

Propagation of this variety is by seed but both male and female plants are required for this, the difference being only really apparent in the flowers.

Euphorbia obesa is similar in that it requires both male and female plants in order to produce viable seed and it is quite difficult to obtain female plants. Unlike E. meloformis the plant bodies, which are hemispherical, are not flattened so sharply at the top although the apex is slightly depressed. The ribs arc very broad with only shallow furrows between them, they arc normally eight in number and have a row of minute leaf cushions on the edges. The plant body is grey-green but develops an almost purplish-brown coloration especially around the top of the plant.

There are a number of hybrid forms, one. which is a cross with £. submammillaris, has a curious branching habit, a feature never found in the true species. It requires a very well drained soil and it is a good idea to mix a little extra sand into the potting com-

not water the plants unless you are certain that they need it as they are difficult to replace if they die.

Both the preceding species are characterized by a thick turnip-like root; E. valida. which is thought by many to be a natural hybrid between E. meloformis and E. obesa, lacks this feature. Although broadly spherical when young, as it grows older it assumes a more cylindrical shape and can attain an ultimate height of a foot (30 cm) or more and occasionally branches from the base. Superficially. on the other hand, it is almost exactly halfway between the two species -the body being furrowed as in E. meloformis but not quite so deeply. The dead flower stems are even more persistent than those of E. meloformis and may last for several years before ultimately falling off.

The three species illustrated on this page are quite unique in appearance amongst the euphorbias although another species with a turnip-like root is E.pseudoglobosa; however, this has oblong shoots rather than hemispherical ones and is seldom offered for sale on a commercial scale.

out by means of cuttings following the drying out and healing procedures given at the beginning of this section (page 165).

Considerable confusion seems to exist, particularly in the United States, between rast to the species described on (he opposite page (hcse (hrcc form large trec-like plants and have a distinctly cactus-like appearance. The absence of any form of felting in the areoles and the tendency to produce rudimentary leaves from the growing tips of the plants, especially if cultivated during the summer in a warm, moist atmosphere, clearly differentiate them from the true cacti. In fact the areoles at the base of the spine are not areoles at all but leaf cushions or tubercles.

E.herr ficent plant with a really savage appearance. 1 often wonder if it was dried, cut into sections and used as a weapon by primitive man. It is a native of Natal and Zululand. Kenya and Tanzania and there it forms an immensely spiny succulent shrub with many three-angled stems branching upwards from a low trunk. Pot-grown specimens normally branch less freely and seldom before they are five years old or more. Each year's growth is clearly identified by the segmented character of the stem as it tapers towards the base. The margins are wavy and carry tubercles each of which produces two long hard spines opposite one another at the tips. The margins seem to be specially hardened and are not soft and fleshy like the rest of the plant. The flowers, which are fairly freely produced, appear between these spines at the top of the plant and arc somewhat inconspicuous, hardly rising above the level of the greyish-green stems, although subsequently attractive rose-coloured fruits are produced which show up more clearly. Propagation is best carried

out by means of cuttings following the drying out and healing procedures given at the beginning of this section (page 165).

Considerable confusion seems to exist, particularly in the United States, between as long ago as 1858 when Lemaire, the famous cactus collector after whom Lenuiireocereus is named, wrongly identified some plants he brought back from Gabon. The most important distinguishing feature of E.lrigona is the white variegation down the sides of the three-angled stems and the well developed leaves that often persist for 6 in (15 cm) or so down the sides of the slems. It is a native of Southwest Africa and although it normally has three angles to the stem some are reported with four. It branches freely even when quite young making an attractive plant for display in the corner of a room or at the back of a succulent bowl. In commercial horticulture the species normally sold as E. irigona which lacks the white marbling of the true species and the persistent leaves referred to above is known as E.hermen-liana. a very fast growing kind which maintains its rather more slender appearance. It is possible that it is really E. anliquoruni in many cases.

Euphorbia ingens is one of the most impressive of all succulent species in its native habitat on the west coast of Africa. It forms a large tree up to 30 ft (9 m) in height with spreading branches and a tall considered by grow older more ribs develop; this is especially true of the branches which are always four angled and are constricted into segmenis. The young stems often appear to have a hint of variegation about them.

All the tree-like euphorbias so far discussed need a somewhat warmer temperature in winter if they are to do well; otherwise they can develop hard brown woody patches on the stems similar to those of Myrtillocactus geometrizans and although this does not actually harm the growth of the plant it spoils the overall appearance, and can be prevented. There are several other tree-forming species of Euphorbia, the most commonly seen of which is probably E.neulra; this is easily distinguished by having five or six angles on the branches rather than the four of E.

with E.cc it first three angled b

Euphorbia (continued)

In contras! to the species illustrated on the previous page ihe ones on ihe presen! page lend lo produce shorler more compaci planls which branch more readily when much younger.

species which seems to be very popular. Il grows on Ihe Alias mountains south-west of Marrakesh where it makes low spreading clumps, This habit is not too obvious in pot-grown specimens which normally have a central upright column round which rudimentary branches seem to form, mainly at base level. In the course of time these lill out and grow round the main stem, packing themselves closely in so as to give the plant its humped appearance. The stems are an attractive grey-green colour even when older with four broad angles which give the plant a geometrical appearance. The ribs are notched a little in between the leaf cushions or tubercles and the spines, which are fairly short and brown in colour, are produced in pairs from the tips of the old leaf cushions.

A drug is produced from the plant, which is one of the few species of Euphorbia which is not poisonous. The name of the genus is. in fact, derived from that of Euphorbus who was physician to King Juba II of Mauretania. It is related that the plant was actually named by King Juba in honour of of the physician and he subsequently wrote a treatise on the herbal properties of the plant called De Euphorbia Herba. It is one of the oldest names in botanical Latin, and E. resinífera was almost certainly the species 168 about which King Juba wrote.

Euphorbia mammillaris has joints which resemble com on the cob in shape if not in colour and for this reason it is often referred to as the corncob cactus. It is. however. quite definitely a euphorbia and is not related to either of the plants which il is supposed to resemble. It is a somewhat ungainly plant and those with limited space at their disposal should grow the dwarf version illustrated beside it. It is normal to see commercial specimens growing upright, frequently supported by a cane; however, in Cape Province where it is naturally found, it forms a low sprawling ground cover, seldom more than 6in (IScm) in height with a short trunk and suckers sprouting up round it near the base. The stems are mainly unbranched although when supported by a cane they may often appear to be branched, this is merely the effect of trying lo grow ihe plant upright. The stems are surrounded by flattened rows of tubercles, giving it the appearance of having numerous ribs. These are often twisted a little to form shallow spirals. The flowers are produced on twiggy stems near the tips of the sideshoots and the dead stems persist for some years (as do those of the globular euphorbias described earlier) to give the plant a slightly prickly appear-

Those who do not have the space to grow a sprawling plant such as E. mammillaris can always opt for its 'dwarf version E. submammillaris, which is also a native of the Cape Province. In spite of its name il differs substantially from the true E. mammillaris in having acutely angled stems with nine or ten ribs rather than ihe spirally arranged rows of low tubercles characteristic of that species. The stems are very slight, seldom more than half an inch (1 cm) thick, and the plant branches freely from ihe base rapidly making a small neat clump even in a 3-in (8-cm) pot. The branches have fewer angles with rather more prominent ribs than the more rounded stems. The predominant colour is a pale greyish green, the ribs of the branches are sharply notchcd and the sides are sharply furrowed. Like the globular species it produces small flower shoots al the tips of the branches whose dead stems persist for some time. They are in themselves quite attractive as they have a reddish colour when young.

In a greenhouse il is wise to keep this variety on a slatted shelf in the winter as il is particularly susceptible to damp cold weather and appreciates a good flow of air round the branches which helps to ripen and harden them against any possible infection.

Considerable controversy exists over the exact nomenclature of the species illustrated on this page and commercial growers seem undecided as to which plant is a subspecies of which - if any.

Euphorbia milii is now sometimes sold as E.milii milii and it forms a graceful little shrub. Strictly speaking it is not succulent at all but since it tends to drop its leaves in winter and is always grown alongside other succulent plants I have seen fit to include it here. The variety illustrated is a native of Madagascar and has thin somewhat weak spines seldom more than quarter of an inch (6 mm) in length and about a tenth of an inch (2 mm) thick. The leaves are the most succulent of all those in the group being tough and leathery and conspicuously narrowed towards the point where they join the stem. The flowers, as mentioned in the introduction to this section, are the inconspicuous yellow things in the centres of the so-called 'flowers' which are. in fact, a type of bract known as a cyathophyll.

The best variety to grow has been raised by Koeniger, the noted cactus specialist at Aalen, near Stuttgart, and called in honour

This has very weak rather flexible spines and flowers almost continuously throughout the year. The slender branches grow into a compact pyramidal shape and make it especially suitable as a pot plant.

The much larger E. m. splendens is frequently referred to commercially either as E. splendens, or as E.s.bojeri, or even as which has been colloquially given to it of crown of thorns is almost certainly theologically and botanically inaccurate. As a description, on the other hand, it is very good as the shrub, which can attain a height of over 6 ft (2 m), is well armed with long hard spines up to 6in (IScm) or more in length and nearly half an inch (1 cm) wide at the base. It is generally much larger than the preceding species and the leaves although bigger are less succulent. The flowers are produced in branched clusters on sticky stems that grow out of the side of the plant near the tips of the branches but also occasionally from older wood. They are much larger than those of E. m. milii and although they are produced almost as continuously during the year the main flowering period is definitely in the spring and early summer.

It bleeds extensively when cut and the instructions on propagation on page I6S should be followed. Care should also be taken not to allow the milky latex to come into contact with the eyes, lips, or blood as it can cause considerable discomfort and swelling. If you feel some pufliness after potting or handling the plant it is advisable to call a doctor and explain what has happened. It is hardly fatal but some people seem more allergic to it than others and given the right treatment the swelling will quickly subside.

Even if adequate precautions are taken propagation is difficult on account of the woody nature of the stem and the rapidity with which it drains, and it should not be attempted on any scale without mist cultivation and a special propagator unit capable of maintaining the humidity round the plant without allowing it to rot off.

Euphorbia milii Tananarive, also referred to as E. splendens Tananarive, is easily distinguished by its yellow cyathophylls, which are slightly tinged with red when given full sunlight, and its more sprawling appearance; normally it requires staking and judicious pruning if it is to make a shapely plant. There is also a variety with pink flowers called E. m. hislopii which is otherwise similar in appearance.

All these xerophytic or woody species tend to drop large numbers of leaves whenever they are disturbed. This means that not only docs the high-street retailer lose a few leaves but that the ultimate consumer will also lose some leaves when the plant is first brought home. There is absolutely nothing wrong in this at all and the plant will rapidly make fresh leaves as soon as growth starts up. The main indication of trouble is a shrivelling of the stems and if this is noticed it is best to cut off the affected portion since the shrivelling normally starts at the growing point.

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