Theva of plants with the same specific name in the cactus family is nowhere more apparent than in the immense variety of forms of Mammillaria elongata. The plants are all distinguished by having long thin cylindrical stems which form clumps at the base when quite young. The commonest forms of this plant have cylindrical plant bodies about 6in (15cm) in height at the centre although sideshoots may be almost prostrate along the surface of the compost. The tubercles are cylindrical and the amount of wool in the axils is very small, often in fact they are completely bare, even near the growing tip of the stem. The radials are neatly arranged in a star-shaped pattern on the arcoles and normally number eighteen or so. They are usually reddish in colour but this is one of the most variable features of the plant. The centrals are generally four in number and difficult to distinguish from the radials as they frequently spread out sideways like the radial spines. The true M. elongata has yellowish flowers but cultivated specimens may have all manner of different coloured flowers, largely I think as a result of hybridization rather than the effects of natural variation.
When grown in partial shade such as exists on a windowsill the stems will tend to become rather thinner than if grown in a greenhouse, and flower production will consequently be somewhat diminished, but the plant makes a good house plant as long as it is not allowed to become waterlogged which can cause a rapid rotting olf. It is a cactus which is generally more tolerant of drought than deluge and if in doubt the best
The most commonly sold form of M. elongata is M.e. rufo-crocea, which has much more prostrate stems and a conspicuously brown-tinted central spine banded into areas of white and yellow at the centre and near the base. Another variety seen is M. e. siella-aurata which has much more golden-coloured radial spines as its name suggests. Plants thought to belong to this variety should be compared with the illustrations above of M. microhelia and M. microhehop-sis. both of which resemble the variety in spine configuration and colour.
Mammillaria microhelia was formerly known as Leptocladia microhelia but the two names are synonymous. It differs from M. elongata and its varieties in having a solitary stem usually about 4in (10cm) in height. It is a native of Central Mexico where it grows near Queretaro in the Sierra dc San Moran at an altitude of some 7.000 ft (2,100 m). The stems are bright green and a little wool is occasionally, but not invariably. present in the axils of the younger tubercles. The spines are the most attractive feature, the radials being arranged (as the name suggests) to form a little sun around the somewhat elliptical arcoles. They are very numerous and quite short but firm rather than bristly. The true species has a solitary unhooked central spine on the upper arcoles although this drops off with age and is usually lacking completely round : of the stem. The central spine i
The flowers are somewhat variable, mainly due to hybridization again, the true species having creamy-yellow flowers: plants with pinkish flowers arc probably either M.microheliopsis. also illustrated above, or a hybrid between the two.
commonly found in cultivation as the preceding variety as it is generally rather slower growing and consequently somewhat smaller in size. It is sometimes referred to as M. microhelia microlieliopsis and it is certainly very similar to the preceding species. Some warmth is appreciated in winter although if it is in a well drained soil and given a sunny position it will be all right with the bulk of the collection in a frost-free greenhouse overwinter. It does not generally do well indoors, tending to grow even more slowly and being an unreliable flowerer in this situation.
The chief difference between M.microheliopsis and M. microhelia is the pale grey or pinkish tinge on the central spine of the former as opposed to the brownish coloration on the central spines of M. microhelia. Although the flower colour of the two species differs as mentioned earlier, those of M.microheliopsis being pinkish, this is not always a reliable guide.
reddish with the golden radial o well
Mammillaria gracilis is popular with commercial growers and amateurs alike on account of the ease with which the ntimerous branches can be broken off the plant and rooted. The best rooting medium I have found is pure washed river sand, and if this is kept just moist the plantlets will root rapidly into it and quickly become established in their own right. The stems are very short, seldom exceeding 3 in (8 cm) or so in height, and the branches are formed not just from the base as is the case with most mammillarias but also from the upper parts of the stem, ultimately forming small clumps nearly 4 in (10cm) in diameter. The numerous white radial spines are pressed back round the sides of the stem and appear to cover the whole of the plant body. The ccntral spines are rather more prominent near the top of the plant and are frequently lacking near the base of established clumps. The flowers are not so freely produced as the branches, and are yellow with a very faint orange or even pinkish stripe in them.
It is possible that M. gracilis will benefit from regular fertilizing, particularly where this can be done with an organic plant food which will help to raise the organic level of the soil. If this is done it is best to make the plant one of the first to receive water and one of the last to be dried out each year.
There are some varieties of M. gracilis which lack the dense covering of spines of the species illustrated and it is possible that the majority of these are a variety known as \1. g. pulcliella.
Mammillaria kewensis is a variety which is frequently labelled as such in the shops but is hard to find in most books on the subject of cacti. From plants which have passed through my hands there seems little distinction between the plants labelled as M. kewensis and those called M. hidalgensis. the most significant difference being in the colour of the spines and flowers.
Mammillaria kewensis forms solitary elongated plant bodies up to a fool (30 cm) in height whose dark green stems have a slight covering of wool in the axils of the tubercles on the upper part of the stem. The spines are very variable: plants which I call M. kewensis having no radial spines at all. the areoles supporting instead four central spines with a slightly purplish to black coloration. The younger areoles are densely packed with white wool but this disappears with age. The pale pink flowers are produced fairly freely, even on quite young
Mammillaria hidalgensis. on the other hand, is a rather smaller plant, although this may not at first be obvious. The crown of Ihe plant is densely filled with while wool produced in the axils of the tubercles, which are ralher unevenly and openly arranged round the sides of the plant. The spines are like those of M. kewensis. extremely variable but greyish brown rather than purple. The flowers are a much darker red.
Bolh varieties may benefit from a little shade during the summer, especially if grown in a greenhouse, and should be stood in a position where shadows from other members of ihe collection fall.
Mammillaria kunzeana could at first sight be easily confused with M. bocasana (illustrated and described on page 150) but il differs in having only a very few occasional bristles in the axils in between the tubercles and no wool. The plant bodies are fast growing and quickly form low clusters of stems each of which is generally less than 2 or 3 in (5 or 8 cm) in height. The stems themselves, although covered with spines, are glossy green with scaly somewhat cylindrical tubercles which in turn are slightly stippled themselves. The radial spines are very numerous, frequently more than twenty-five in number, white, thin and somewhat woolly in appearance. The centrals seem very variable in colour and quantity. Plants I have grown tend to have up to four grey or occasionally straw-coloured central spines, bul other authors describe this species as having solitary brown spines or up to four brown spines. The flowers are very much more ornamental than those of M. bocasana being larger and cream with a central pink stripe down each of the petals.
Mammillaria muiuhii and M. mmdlii arc. in facl, the same variety, the misprint 'nundiii' being of commercial origin but widely perpetrated. It is quite common to find such spelling mistakes occurring, particularly who may not have time to check the printing on some of his labels. A similar example is Harioia salicornioides which is frequently listed as Haliora salicornioides but is. once again, the same variety.
Mammillaria mundlii makes a low globular plant spreading almost as wide as it is high. The dark green stems form a woolly cephalium or hat when older due to the profusion of wool growing between the axils of the young tubercles, but this feature does not normally appear on young plants below three or four years in age. The radial spines and spreading with two brown central spines sprouting from the areoles which, like the younger axils, are woolly at first. Although a rather uninteresting plant it is very attractive when it flowers as the somewhat tubular red flowers are produced well clear of the tubercles as opposed to being hidden down in the axils, which is the
It is normal for plants of M.phunosa to be grafted when sold in Britain. This is not absolutely necessary if the plant can be grown in a very well drained soil and watered carefully. It is very similar in its cultural requirements to M.schiedeana, described and illustrated on page 156. It is somewhat rare in cultivation, being a shy 154 flowerer and only forming clumps at a rela tively older stage in its life and thus being difficult to propagate in any quantity. During the winter it will need a little extra warmth and can either be stood right next to the thermostat or brought indoors. However, it also needs to be kept completely dry during this period, particularly if it is grafted as the most common stock is Hylo-cereus which has been already mentioned as needing a slightly higher temperature itself.
In spite of its rarity and the difficulty of cultivation it is a particularly sought-after species on account of its very ornamental spines. These are very numerous and white and arranged exactly like feathers in the areoles completely covering the dark green plant bodies which, when mature, can attain a height of 6in (15cm) or so. Its native habitat is Northern Mexico where it grows in rock clefts near Coahuila and this accounts for its aversion to water. If grown in a bed rather than in a pot it is as well to try and reproduce this sort of habitat for it.
The flowers, as already mentioned, are seldom produced in cultivation until the plant has attained a fair size. When they are produced they are small and white and the seedpods arc black, contrasting well with the white bristles. I have never grown plants from seed, but it is probably quite a difficult variety to raise in this way and it is. therefore, a sound idea to graft them as soon as they are large enough to handle to minimize the risk of damping off occurring in the seed tray when they are young.
Mammillaria prolifera. although very much more common than the preceding species, is altogether a better plant for the amateur, being tolerant of every kind of abuse and flowering very freely. As its name suggests it has an almost uncontrollable habit of proliferating clumps, sometimes groups of plants can measure a foot (30 cm) or more in diameter. Flowers are produced very freely on plants with just a single stem and a whole clump in flower is really worth seeing. It is tolerant of adverse conditions and will do well wherever it is grown, although it will derive considerable benefit from being given the maximum amount of sunlight possible. The small offsets root readily and make this a popular plant for own-propagation enthusiasts. If grown indoors during the winter it will need a little water, especially where it is overwintered on a living-room windowsiU, but if left in the greenhouse it should be allowed to dry out just like other cacti.
Mammillaria prolifera has several varieties, two of which are most commonly seen. M. p. Iiaiiensis has a much more dense covering of spines than the illustrated species and centrals which are yellow at first and only become white with age. M.p. texana is a mainland version of a variety which is otherwise a native of the Caribbean. It is rather more open in texture and forms even larger clumps.
In spite of its name Mammillaria pygmaea is not a particularly dwarf variety in cultivation, the elongated, somewhat club-shaped plant bodies, which are broader at the top than at the base, forming large clusters at a fairly early stage in life and generally attaining a height of some 4 in (10cm) or so. The stems are a glossy bluish green and the whole plant resembles a somewhat small version of M. wildii, illustrated overleaf, with which it is sometimes confused.
In its natural habitat the plant is considerably smaller and if you want to duplicate this feature in cultivation it is probably best to give it poor soil and to water sparingly, this will also have the effect of concentrating the areoles more closely together. The radials normally number about fifteen and arc white in colour. The areoles support four central spines arranged in a roughly cruciform fashion and the lower two of these are usually slightly hooked. There seems to be some variation in the flower colour as well as in the size of the plants -the flowers ranging in colour between red
Mammillaria rliodanlha is another very variable species and several of the varieties more commonly seen in cultivation have been given Latin varietal names. Generally the plants are solitary and cylindrical although younger plants may be globular at first, elongating only in the fourth or fifth year of cultivation. It is also not uncommon for plants of this variety to split into two at the growing point of the stem and this should not be regarded as anything to do with bad culture. The plant bodies are comparatively tall, often attaining a height of I2in (30cm) or so even in cultivation. The stems are greyish green in colour, occasionally darker, and the younger axils between the tubercles produce a fair quantity of white wool. The radial spines are normally about fifteen in number and are very variable in colour, the type normally has whitish spines but these are occasionally suffused with pale yellow. The centrals, too. are variable both in colour and number, normally three to six in the type, red or brownish red in colour and tipped with a
Flowers are fairly freely produced in late summer and form a ring of reddish blooms round the upper parts of the plant. As with many other mammillarias with few spines it should be shielded from direct continuous sunlight if grown in a greenhouse.
Amongst the more commonly found varieties are M. r. sulphurea, also known as M.fuscaiu sulphurea, and M.r.pfeifferi which has a conspicuous covering of yellow spines but is much less free with its flowers. M.r.ruherrima has reddish spines and is also sometimes sold as M.r. rubra. M. pringlei with its very dense covering of yellow spines is also very similar to M.r. sulphurea.
One of the first mammillarias that any beginner should obtain is undoubtedly M. schelliasei. Not only is it comparatively free flowering even when quite young, but its greenish flowers are produced right at the beginning of the flowering season and it may be forced for early flowering in the way described for Parodia sanguinijhra on page 147.
The plant bodies are of moderate height for this family, growing to about 6 in (15 cm) in cultivation. They rapidly expand after the fourth or fifth year to form large clusters of plants, although it is unusual to find this occurring until the central plant is well established on its own. The stems are greyish green in colour and the tubercles, between the axils of which a certain amount of wool is produced when young, are cylindrical with very slight angles on them. These tubercles are very fleshy and care should be taken when handling them as they detach readily leaving an obviously scarrcd part of the stem. The radial spines are normally about fifteen in number and are straight, bristly and white in colour. The centrals are hooked, which makes it easier still for the tubercles to become detached, and brownish in colour.
Although green in colour the flowers are fairly freely produced and 1 have always had a personal predilection for plants with greenish flowers as being a little unusual.
Mammillaria glocliidiaia is somewhat similar in appearance but forms clumps rather more rapidly than the illustrated species, the flowers are pale pink in colour and it is possible that plants of M. schelliasei which have a pinkish tinge in the green flowers are. in fact, natural hybrids between the two species.
Mammillaria schiedeana has already been mentioned as being somewhat exacting in its cultural requirements and for this reason it is often grafted. However, it is considerably easier to grow than M.plumosa and cessfully if given an open well drained slightly sandy compost and if care is taken not to allow water to sit amongst the very fleshy tubercles, especially if the sun is not shining brightly enough to help it to evaporate quickly.
The plant bodies are rather slow growing and prefer full sunlight, which assists in maintaining their somewhat dwarf globular appearance. When grafted they form branches from the base in their third year or so but when grown on their own roots this branching habit may not develop until a little later. The stems themselves are dark green and are covered with very long thin tubercles which give the plant its somewhat vulnerable habit. The radial spines are weak and very numerous, often as many as thirty in number, and spread in a hair-like fashion against the outer edges of adjacent tubercles appearing to clothe the plant completely. The young spines are a clear white but as they grow older they become yellow, reversing the normal colour change which occurs in cactus spines, but contrasting magnificently with the dark green plant bodies. Cultivated specimens normally lack central spines but I have seen imported specimens which have solitary central spines
Although it is very slow growing the 156 plant bears flowers freely even when quite young. These are greenish yellow and are produced from the axils amongst the tubercles. They barely extrude above the covering of hair-like spines and can easily be missed. Grafted plants tend to produce rather larger flowers.
Mammillaria spinosissima is another rather variable species, the locality in which it is found in the wild having as much to do with variation as any natural tendency to hybridize with adjacent species. The plant bodies are generally solitary and although globular at first become cylindrical with age. The dark green stems produce white wool in the upper axils between the flattened cylindrical tubercles. As its name suggests it has a great many spines. The radials are about twenty-five in number and are white and spreading in the type, although these may vary in some of the named cultivars and varieties. The centrals are similarly variable but the type has anything between seven and ten of them projecting outwards and downwards slightly away from the plant bodies, giving the plant its somewhat hostile appearance.
It flowers fairly well once established, producing a ring of bright red blooms round the upper part of the plant. The varieties grown commercially tend to be very much less free flowering although more exotic in their spine colour. One of my favourites is M. s. sanguined which has magnificent red central spines tipped almost purple when young.
Mammillaria geminispina is another well armed species, with spines nearly 1J in (4 cm) in length and pure while in colour.
M.g.nivea has even longer, pure while spines which are normally clustered in threes on the areole. as opposed to being in
Mammillaria wttdii is a well loved and free-growing species. It makes an excellent house plant as it does not require an extended cold period in order to flower, nor does it have to have the same quantity of winter light to enable flower-bud initiation to occur. At first globular, the stems later become cylindrical, attaining a height of about 6 in (15 cm) in cultivation and branching freely at the base from the second year onwards to form fairly dense clusters. The stems themselves are bluish green but the tubercles become progressively paler towards the areoles being almost white at the lips. The radials are while or pale pink in colour and number about nine. The areoles, which are al first woolly, produce three or four straw-coloured central spines, the longest of which is hooked.
It is very free flowering, and ihe true species has a ring of white flowers, faintly suffused with pink near the edge of the petals. It has been hybridized with M. glochidiaia and the resulting hybrids, although similar in every other respect to the illustrated species, have pinkish flowers. The fruits form readily on pollination but arc kept hidden in the axils until the following year when the long red tubular berries appear at the same time as the current year's flowers. Easy to grow, it is best kept away from direct sunshine, a factor which makes it a valuable indoor plant, and it should be watered sparingly.
Mammillaria zeilmanniana is. possibly, the cactus most commonly offered for sale throughout Britain. This is because it comes very readily from seed and flowers profusely even when quite young; but it is not an easy plant to grow and specimens will unaccountably collapse both in the early spring when water is first applied and the plants start to expand, and during the autumn as they are dried off prior to their illustrated on the opposite page but it differs in being glossy green, having pink instead of white flowers and lacking the progressive pallor of the tubercles as they get further from the main stems.
It is a freely clustering plant and even two-year-old seedlings may start to form offsets round the base. Because of its susceptibility to fungal infestations it is a good idea to remove these offsets as soon as they are large enough to handle and to root them in a tray filled with fine washed river sand. When they have established root systems they can then be potted up separately and grown on as an insurance policy against an attack of pythium or fusarium which may knock out the main specimen in the collection. Although they grow quite tall in their native Mexico they seldom attain any great height in cultivation because of this susceptibility to disease. 1 recommend watering regularly with a systemic fungicidc such as benomyl and regular, possibly even fortnightly. inspection of the roots to make sure that the tips are still white. If the lips are brownish in colour and break away easily it is probably better lo remove any offsets and to repot the plant into fresh well sterilized soil, cutting the whole plant off above soil level and re-establishing it if Ihe brown rotten roots extend over a considerable part of the root system. There is an which appears lo be slightly hardier.
The species illustrated so far in Ihe section on mammillarias have all had a watery sap. If you are confronted with a plant whose name you do not know but which exudes milky sap when pricked with a sterilized needle, then you should start looking for it in the immediately following pages.
Considerable confusion exists between M. ceniricirrha and M. magnimamma, the second name often being given as a synonym for the first. In spite of its name. M. ceniricirrha lacks any central spine and horticultural specimens sold as such which have a central spine are probably M. magnimamma. Having made Ihis distinction the two species are extremely similar in habit and requirement. Although forming large clumps in central Mexico where they grow wild both species tend to remain solitary when grown in pots in this country.
The younger axils are generally hairless and plants which have very woolly tops are either about to produce flowers, or. if flowers fail to materialize, are wrongly named and probably belong to the group discussed next. Although reputedly free flowering the plants have to attain a fair size before Ihe flowers are produced either regularly or reliably. They are pale pink to red in colour with an occasional backing of yellow in the petals. Generally the more yellow they have the more likely they are to be M. magnimamma.
Mammillaria collinsii and M.nejapensis are very similar varieties with a mass of white wool on the upper part of the plant which does not invariably signify the onset of flowering. Both have yellowish flowers suffused slightly with a greenish coloration.
Mammillaria compressa is another species with dark green prominent tubercles and a mass of white wool in the upper axils. It generally forms clumps round its flattened plant bodies, but otherwise is of very variable habit, sometimes even completely spineless. Its red flowers are only produced on older plants but help lo differentiate it from the two species mentioned above.
It is probable that considerable hybridization has occurred both naturally and otherwise amongst all the species mentioned on this page and this has clearly resulted in the confusion thai confronts the amateur in trying to get a correctly named specimen. Matters are not, of course, helped by the very variable nature of Ihe plants themselves. To summarize one could say that plants with relatively small amounts of wool in the tubercles and no central spine should be referred to M. ceniricirrha. similar plants with a downward pointing central spine are probably M. magnimamma. Where a considerable amount of wool is produced but few flowers the plants are either M. nejapensis or M. collinsii, which bolh have yellowish flowers, or M. compressa which has reddish flowers.
Mammillaria heyderi is one of my favourite cacti but it is, sadly, not as available in cultivation as it should be. This may have something to do with the difficulty we have found in raising it from seed and since it does not form olfsets freely this makes it a problem to work up large stocks satisfactorily. However, since it is very early and very free flowering and can even producc a second flush of flowers later in the summer it is worth trying to get hold of a specimen.
In habit the plant bodies are low and hemispherical at first although in the fifth or sixth year of cultivation they start to elongate, attaining a height of about 4 in (10 cm). The tubercles are pale to grey-green and a little wool is produced in the younger axils between them. The radials are white tipped with brown and are arranged like a star, forming an attractive geometrical pattern round the plant bodies. There is usually a solitary central spine, which in spite of its small size can be very painful. Because of its low spreading habit and sharp spines this is one of the most difficult of all cacti to repot without losing one's temper. The flowers are white with a greenish tinge and are extruded through the tubercles and spines and show up quite
There are several similar species all coming from the same part of Southern Arizona, the most notable of which is M. macdougalii which has between ten and eleven radial spines, slightly stouter and thicker than those of the illustrated variety.
Mammillaria hahniana and M. lanata are two popular cacti loosely referred to as old lady cacti. M. hahniana is the one to which the name properly belongs and is readily identified by its long straggling hairs which protrude from the axils between the spines. There are several varieties of M. hahniana available, the most notable of which is probably M.li.giselina which is frequently sold as the true species but h
Mammillaria celsiana is very much less hairy and is a solitary plant in cultivation, occasionally forming clumps when much older. The plant bodies are round and globular when young but in the fifth or sixth year they start to elongate and eventually become club shaped, slightly thicker at the top than at the base, attaining a height of some 8 in (20 cm). The plant bodies are greyish green and it resembles M.parkin-sonii in this respect. (M. parkinsonii is illustrated on page 160.) The axils between the tubercles produce a considerable amount of white wool but this hardly protrudes beyond the spines which are about twenty-five in number and rather thin and white. The central spines are short but straw coloured and show up well against the white spreading radial spines. The pink flowers are produced only on older plants among the thick wool at the top of the
Mammillaria heeriana makes an upright cylindrical column with a height of some 4in (10cm). The tubercles are slightly angled having a faintly rhomboidal cross-section and are somewhat depressed at the tips below the areoles. The plant bodies are pale olive green in colour although in poor light this may be darker. The areoles, which have a small amount of white wool in them when young, are roughly oval to elliptic in shape and have about eighteen short white bristly radial spines, the longest of which are about a quarter of an inch (6 mm) in length. They are all tipped with a dark reddish patch when young but this fades as they become greyer with age. The four central spines are arranged in a cruciform pattern and are reddish purple in colour becoming paler as they get nearer the areole as well as growing overall rather more pale with age. The lowest of the cluster is normally hooked. The red flowers, which are tubular and extrude through the spines in a ring round the upper growing part of the plant, are very ornamental and are produced during the earlier part of the year.
Mammillaria heeriana makes a good house plant as it does not require full sunlight in order for flowering to take place. It prefers a rather open compost with good drainage and care must be taken to watch for any signs of damping off as this species, like M. zeilnmnniana. is a little susceptible
Mammillaria klissingiana is al first sight a little similar to the old lady cacti described on the opposite page and has a good covering of white hairs like those varieties. It makes a globular plant when young but later adopts a more cylindrical form, ultimately attaining a height of some 6 in (15cm) in cultivation. The plant bodies are glossy green but are almost completely hidden under the dense covering of white marginal spines which are, in turn, confused with the wool between the tubercles. The weak, spreading radials are normally about thirty in number. The.centrals. between two and four in number, are also white, tipped with reddish brown near the point, but are not very long, seldom exceeding a quarter of an inch (6 mm) in
The brilliant red flowers are somewhat small in size but are produced in great profusion in a dense ring round the upper part of the plant which is frequently almost hairless at flowering time. This feature helps to throw the otherwise small flowers sharply into contrast with the surrounding white spines and hairs and is one of the main reasons for its popularity with collectors and growers.
It is frequently confused with M. lanaia illustrated beside it, many of the plants sold as the latter species are properly M. klissingiana, M. lanaia having no central spines and being still a little difficult to find in
Other varieties with numerous white hairs and spreading white spines include M. cliionocepliala, the top of which is almost hidden beneath a snowy covering of white hair and whose flowers are white flushed lightly with pink. The plant bodies are faintly greyish in appearance. M. Candida is a clump-forming somewhat more globular species completely covered in white spines which arc sometimes tinged with pink near the upper part of the plant.
Mammillaria lanaia itself is at first globular like M. klissingiana but becomes cylindrical with age. The tubercles are very small indeed, and are almost completely hidden on the upper part of the plant by the dense tufts of white wool that are produced from the axils between the young tubercles. The areoles are also woolly and carry long slender white radial spines which become tangled up with one another between the tubercles, giving the plant its densely covered appearance. As mentioned earlier there are no central spines on the true species and this is an important distinguishing feature. The flowers are also produced nearer the upper part of the plant than those of M. klissingiana and are only just visible through the dense wool there.
Mammillaria woodsii is one of the most handsome mammillarias and has the advantage that the flowering stages of the plant are clearly marked as it gets older. It makes an upright columnar plant, although when young the stems will be globular, only attaining the true shape in the third or fourth years. The tubercles are rather slim and like those of M. heeriana are somewhat rhomboidal in cross-section. The appearance of the areoles and plant bodies changes dramatically as the plant matures. The youngest areoles near the top of the plant have only a few short radial spines and some wool. The areoles round the flowering parts of the plant have very much longer spines and much more wool, the whole being densely woven into a circular ring through which the narrow-petalled bright red flowers with prominent yellow centres appear. The two central spines arc almost black in colour, the upper considerably shorter than the lower downward-pointing one which is sometimes nearly half an inch (1 cm) in length. The woolly band where the flowers were formed persists for some time but eventually becomes less marked and the lower parts of mature plants arc almost completely hairless and ultimately form a sort of woody trunk.
All the cacti illustrated on this page will appreciate full sunlight. The dense woolly covering is specifically designed to ward off direct sunlight and maintain a cool microclimate round, the upper surfaces of the plants which can be exposed to very intense light in thiir native habitats. If they are grown too dark there will be no need for them to produce so many white spines and much of the intrinsic beauty of the varieties will be lost. During winter they must be kept cool and as dry as possible, otherwise condensation will form on the skin of the plant below the spines and this may result in damping off and the creation of a cold muggy feeling round the plants which they do not appreciate.
Mammillaria parkinsonii is one of a small group of mammillarias amongst which is also found M.rhodantlia. illustrated and described on page 155, which branch from the upper part of the stem to form forked clumps rather than producing a cluster of offsets near the base. It is at first globular in shape but in the fifth or sixth year the plant bodies become conspicuously elongated and somewhat club like in appearance which signifies that the growing point in the tip is preparing to branch into two so as to form the branching shape referred to above. The normal height attained in cultivation is 6 in (15 cm) and the grey-green tubercles which surround the stem are long and exude enormous quantities of milk when pricked with a sterilized needle or pin. A considerable amount of wool and bristle is produced between the tubercles in the younger axils of the plant and this is especially noticeable near the upper part of the plant. The radials. which number twenty-five, are pure white in colour and spread laterally against the plant body giving it the appearance illustrated. The two white central spines are pronouncedly tipped dark brown and the lower of the two is normally somewhat deflected, pointing downwards and away from the plant. The flowers, which arc only produced on well established plants and even then only a few at a time, are creamy yellow in colour with a central darker strip.
The most commonly seen of Ihe other branching species is M.tiegeliana whose pure white spines almost completely cover 160 the plant bodies which starl branching at a height of about 4 in (10 cm). Like M. parkinsonii it is a shy flowerer and very slow growing.
In spite of its unremarkable appearance when young. M. uncinala is worth acquiring. partly for its pale cream flowers and partly for the large vivid red fruits which follow. It is a somewhat depressed, but otherwise globular plant attaining a height of some 3 in (8 cm) in lime. Although easy to grow it is rather slow and possesses a turnip-like fleshy root which means it appreciates a deeper pot than usual, and much of the energy it requires for growth goes into this deep root to prepare it against periods of drought. The tubercles, which are dark green in colour, arc prominently flattened about half an inch (1 cm) in length and the axils between them bear large amounts of white wool forming a dense tuft in the centre of the plant. The radials are about eight in number, white and somewhat bristly, surrounding a brownish-yellow solitary central spine which is sharply hooked at the tip. In the centre of the plant this is the only feature of the tubercles which normally protrudes above the level of the wool, and they are much darker than the older ones nearer the sides.
Although not strictly members of the sub-tribe Coryplianthanae. the Thelocacti bear such a resemblance to mammillarias when young that it has been thought best to include a picture of them in this section.
species and is easily distinguished from mammillarias as soon as flowering commences by its large flattened daisy-like flowers which are produced at the top of the plant rather than round the sides. The plant bodies are generally globular but sometimes become cylindrical with age ultimately attaining a height of nearly a foot (30cm), although this may take a considerable time as the species is very slow growing. The stems are bluish green and the tubercles, which are strikingly like those of a mammillaria. arc arranged in eight spiral rows round the plant. The radials are eight to ten in number, occasionally more, spreading round the sides of the plant and prominently banded in yellow-white with a little red at the base. The centrals, which are four in number, are the same colour.
Full sunlight is required in order for flowering to take place and the plants have to attain a height of nearly 4 in (10 cm) before they are big enough. When the flowers are produced they are very decorative. reddish purple in colour and over 2 in (5 cm) in diameter.
There is a variety which is much sought after called T. b. tricolor which is generally slimmer than the species and has more prominent patches of red on the spines. Those with no red on the spines are probably referable to T. b. bolansis.
Epiphyllum x Cooper
The remaining cactus species illustrated on this and the next three pages are rather different in their cultural requirements and are properly the subject of a special book. They have been cultivated from the nineteenth century onwards because of the magnificent colour and texture of the blooms which have been produced by crossing the true Epiphyllum phyllanlhus with Cereus and Hylocereus species with which it hybridizes readily. The true E. phyllanlhus is a native of Panama where it grows high in the tops of trees making only small roots which serve to anchor it to the tree rather than to draw any nourishment. Accordingly in the greenhouse it must be kept somewhat underpotted and is best grown where air can circulate freely around it. It should also be protected from direct sunlight, preferring a sort of dappled shade such that one can barely see the shadow of a hand when moved across. The compost used for the growing of these plants should be rich in organic matter such as sphagnum moss, leafmould. or sedge peat and should be definitely non-calcareous. In the forks of trees where they grow the 'compost" is mainly vegetable debris formed by falling leaves and other vegetative matter. Those that have more relationship with the cereus with which they are crossed will of course respond to normal cactus compost although they are still best grown in three-quarter pots or pans as they make relatively shallow roots.
Flowering normally occurs in late February and as soon as the buds appear amongst the bristles in the notches in the leaves the temperature should be raised to some IO C (50°F). Failure to do this will delay flowering and may even result in some of the buds dropping off. The flowers extend to June depending on variety and as soon as flowering has finished the plants should be put somewhere cool, shaded and dry for three weeks and rested. If there is no space for this in the greenhouse they may be placed in a shaded part of the garden. This is also the time to repot if they have outgrown their pots. If you do place them in the garden they should be protected from rain, either by being placed under a frame or by being protected by a hedge or wall. Between August and October new growth takes place and the plants will appreciate all the warmth and water they can get. although this should begin to be cut down from November onwards. During the winter some water should still be given and it is probably best to bring them indoors if the cactus collection is to be overwintered in the greenhouse at the correct temperature.
Cuttings should be taken in the early part of the year from above the flowering areoles or after flowering has finished and it is best to slice right across a leaf rather than to take a joint as this provides a better area from which the roots can grow.
There are a very large number of hybrids of which the two varieties illustrated above represent two extremes, and in spite of their Latin names they are really hybrids. Generally all epiphyllums benefit from staking and tying in otherwise they can become top heavy and somewhat unwieldy. One notable exception seems to be E. x eleganlis-simum which lends to adopt a more pendulous habit, at least when young, and flowers freely even on one-year-old cuttings.
Epiphyllum ackermannii in spite of its very Latin-sounding name is probably an early hybrid between Heliocereus speciosus and Nopalxocliia ackermannii. raised in the early nineteenth century. The better varieties have a faint bluish tinge to the side petals and this is a characteristic of their Heliocereus parent. They were subsequently spread among collectors and because of their relative age as hybrids have been elevated practically to specific status. The hybrid plant is very much more common than the true species which is considerably less free flowering. N. ackermannii has rather flatter, less fleshy, branches, which may be quite clearly triangular in section.
Although hybridization has taken place intensively since the mid-nineteenth century a true yellow epiphyllum hybrid has still to be found, although E. x chrysocardium which has fresh green very sharply notched but flattened stems has rich golden stamens and a yellowish tinge round the inside of the throat. The most important white variety is E. x Cooperi which has white flowers produced near the base of the stems, but E. x Weisser Schwann has much larger
Nopalxochia phyllanihoides is one of the cacti which has derived its Latin name from its ancient Aztec one. The Incas called it nopalxochitl. It is one of the oldest species of cactus known to Western man and was introduced to Europe in the middle of the seventeenth century. The form most commonly found at the present time is N.p. Deutsche Kaiserin, a hybrid raised during the nineteenth century which has remained popular ever since. Although frequently sold as an epiphyllum it is normally distinguished from that group by having somewhat rounded stems in places as opposed to the flat leaf-like joints of the previous species. The flowers too are different, being generally somewhat less open than those of epiphyllum and having a more bell-like appearance.
In habit it is a shrubby plant which branches freely both from the base of the leaf-like stems and from joints formed on the leaves themselves. It attains a height of 3 to 4ft (1 to 1-25m) and. because its root system is somewhat shallow, will appreciate staking and loose tying unless you want to grow it as a hanging plant. One good method of tying while maintaining the shape of the plant is to use split canes to support the main leaf stems and lie them to the canes with raflia or a soft stem lie.
The Whitsun cactus, or Schlumbergera gaerlneri. is deservedly extremely popular and there has been some recent hybridization between Schlumbergera and Rhipsali-dopsis to produce a plant with the hardiness, of the former and the more open flowers with the delicate shades of the latter. The species is also known variously as Epipliyl-lopsis gaerlneri and Rhipsalidopsis gaerlneri and is a native of the Santa Catharina state of Brazil. It is very similar to the Christmas cactus and is often confused with this, the main distinction being the rather less serrated edges to the leaves. The joints or leaves are pale green sometimes tinged slightly red at the margin. In the indentations on the margins there are a few brownish bristles and at the flattened end of each joint there is often a considerable tuft of bristles.
The fl&wers are spectacular and produced plentifully in plants of one year old when struck from cuttings. The first signs appear in late winter when red pimples can be seen in the tufts at the end of the joints. These mature very slowly and although you will notice that they tend to grow more on the side with the light, do not turn the plant round as this may cause some of them to fall. When they do develop, individual flowers may remain open for some time. The ovary at the base of the flowers has five very prominent angles to it which is a distinguishing feature of this group. Species or hybrids with four-angled ovaries are probably S.russelliana or S.bridgesii, the main distinction between them being in the shape of the flowers, those of the former being quite regular in appearance while those of the latter have rather uneven petals.
There are many different varieties of Christ-m'as cactus, Zygocactus truncatus, on the market. The most common has cerise-coloured flowers but one variety, Z. I. deli-caius. has almost white flowers, while the variety Weihnachtsfreude has orange flowers. The flower buds appear at the end of the prominently toothed joints during November. By increasing or lowering the temperature the actual timing of the flowers can be hastened or delayed so as to make them coincide with Christmas itself. In commercial establishments these plants are given short days from mid-September onwards by the use of blackout to reduce the hours during which sunlight is available to the plant to between eight and ten. Normally Christmas cacti require about six weeks of this treatment, after which they can be grown on normally.
The joints are up to 2 in (5 cm) in length and are sharply cut off at the growing point, unlike those of the preceding species which are more oval in appearance. The flowers, as has been mentioned already, are extremely variable as are the teeth on the sides of the joints, and many of the weaker hybrids which were raised at the beginning of the present century have to be grafted in order to grow well. The most commonly used stock for this purpose is Pereskia. and normally a single shoot grafted on to the top of the stem and pinched repeatedly will produce a good bushy hanging clump.
Rhipsalidopsis rosea lipl
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