Dolichothele

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Dolichothele longimamma is an excellent species for the small collection as it provides variety of shape in a group which is otherwise somewhat similar in general characteristics. It is a native of Mexico where it is found near such unpronounceable places as lxmiquilpan and Zimapan. It quickly forms a clump of plants and the most characteristic features are the grass-green very long cylindrical tubercles which completely swamp and conceal the plant bodies. On some wild specimens tubercles have been observed as much as 3 in (8 cm) in length although Ihey are unlikely to grow to this size in cultivation. The radial spines are weak and yellowish in colour, not very neatly arranged and giving the plant a rather untidy appearance. The solitary central spine is rather sharper and needle like, very variable in length.

A well established plant produces the large sulphur-yellow flowers in great numbers. Unlike most of the more common mammillarias these are produced well clear of the tubercles of cultivated specimens, whereas the flowers of most varieties tend to be tucked away between the tubercles and make up for their dwarf size by iheir great profusion."

It is an easy plant lo propagate as the very succulent tubercles can be snapped ofT and rooted readily on their own without the need to separate a whole clump from the main stem. These tubercles, although solitary at first, will soon start to pul up additional tubercles round the base of Ihe plant and ultimately will produce a perfectly conventional plant.

Mammillaria

Although undoubtedly one of the most popular of cacti, Mammillaria bocasana is not ideally suited to cultivation on the average windowsill as it prefers full sunlight during the winter if the small flowers in the greenhouse, also, that the part in which it stands is not overshadowed by a brick wall or anything else during this period as flower production will otherwise be inhibited. In the greenhouse in which the cacti are grown on our own nursery 1 remember a disastrous crop of this variety which was grown in the shadow of a large packing hall and which completely failed to flower the following summer.

The plant bodies are low and globular and form clumps, branching in the main from the base, and single plants may often attain a height of some 6in (15cm). The bluish-green stems are almost completely covered by fine while hairs, which come out of the axils between the tubercles, and the very numerous long fine hair-like radial spines that come from the areoles themselves. The centrals are erect and sharply hooked and make it a dangerous plant to put at the edge of the collection as it can be difficult to detach from clothing. They are reddish brown, or occasionally yellow, in colour.

Although freely produced in the right environment the flowers are a little incon-

spici h grey in it they are followed by magnificent pink seedpods which can be over an inch (2-5 cm) in length. Fresh seed from these pods germinates readily and it is advisable to save some as the very fleshy plant bodies of this species are particularly susceptible to fungal

Mammillaria bombycina is similar to M. bocasana not only in appearance when young but also in its cultural requirements. It needs full sunlight and should be watered sparingly, if at all, both at the beginning and end of the season. It is not ideally suited to the windowsill and flower production may be reduced by growing it in such a position. In order to get some flowers on it the plant should be grown in a south-facing window during the summer if possible and transferred to a north-facing one at the beginning of September, then brought back on to the south-facing one again in late March. The plant bodies, which are at first globular, become cylindrical with age and form large clumps when mature. The stems are bright green below the coverin; of hairs and the tubercles are somewhat cylindrical. The radials are very numerous, up to forty if you have the patience to count them, and. like those of M. bocasana, are weak, white and hair like. The three or four central spines are normally flushed with a reddish-brown coloration and sharply hooked at the tip.

The flowers are very much more impressive than those of the preceding species being bright pink in colour and showing up clearly against the background of spines and hairs. The pinkish petals have a much darker red stripe down the centre which accentuates this contrast. It is still unfortunately a little hard to come by commercially but is worth seeking out.

Although not nearly as common as il should be in collections. M. eryihrosperma is another excellent addition to the small collection. One of the greatest problems with members of the Mammillaria genus is their great tendency to cave in to fungal attacks in the lale spring and autumn when they seem to be at their weakest. This is particularly common in plants of M. zeil-manniana illustrated on page 157, and M. eryihrosperma makes an excellent substitute for this if you want a free-flowering red cactus. The plant has glossy-green cylindrical tubercles with a few hairs in the axils between them and rapidly forms offsets to make large clumps. The radials are numerous and are long, white and ihin and at least one of the two or so russet central spines is prominently hooked at the lip. It is fairly common throughout Mexico and the flowers and fruit arc bright carmine-red.

In spite of its untidy appearance Mammil-laria camplolriclia makes a good addition to the collection as it flowers quite reliably even when fairly young. It is sometimes referred to as Doliclioihele camptoiricha and should be distinguished from the species illustrated beside it, Mammillaria decipiens, to which it has a slight resem-

The plant bodies are bright green in colour and grow rapidly to form large clumps, slightly pointed at the growing point in the centre. The tubercles are very long and slender, often nearly an inch (2-5 cm) in length and the axils between them carry a few bristles. The most prominent feature of the plant is. however, the interlocking net of twisted spines which is produced from the areoles at the tips of the cylindrical tubercles. These spines are four or more in number and pale yellow in colour, although there appear to be a large number of varieties and I have seen some plants with almost pure white spines which are most attractive. Although they cover the plant very densely and give it a well protected appearance the spines are not sharp, rather they are somewhat bristly in character. The flowers are a great plus for the plant, they are white and are generally produced in a circle near the base and have the added advantage of being slightly scented, a feature which is comparatively uncommon in this genus.

This variety appreciates a fairly rich soil and may. unlike many cacti, be fed regularly during the summer using any proprietary feed and following the manufacturer's carefully. Watering during the summer can take place two or three times a week with beneficial results, especially if the compost is well drained. During the winter, however, it will benefit from a little more warmth than most cacti and if practicable it should be given a light north-facing windowsill on which to hibernate rather than being left in a cool greenhouse with other cacti.

Mammillaria decipiens is a more tolerant plant but lacks the very ornamental spines of the preceding species. The dark green plant bodies grow quickly and form dense clumps like M. camptoiricha and the height of the clumps is normally similar, about 4 in (10 cm). However, the plant bodies are more globular and less obviously conical in shape. The tubercles are conical and as long as those of the previous species, but the radial spines, which number about eight, are very much shorter, normally white in colour and occasionally suffused with brown. The central spine is solitary and very much darker in colour, sometimes up to an inch (2-5 cm) in length but more commonly a little shorter, bristly rather than spiny. The flowers are produced in the same way as they are with M. camptoiricha, that is in a ring round the base of the plants, but I have been unable to detect even the slightest trace of a scent from them.

As mentioned earlier it is considerably easier to grow than the previous species, does not need so rich a soil and can stand cold in the winter if given plenty of drainage. If the plants are grown in plastic pots in sterilized garden soil it is a good idea to mix in some coarse shingle to assist in drainage.

Mammillaria bogotensis is now regarded, by some authorities as a variety of Mammillaria columbiana and frequently sold under the name M. columbiana bogotensis. The stems are solitary at first but form clumps as they grow older, although this will not normally happen until the fifth year or so has passed. Ultimately they attain a height of over 6 in (15cm) making a comparatively tall plant. The stems are mid-green but like so many other cacti become greyer with age especially around the base. When young the axils between the tubercles are filled with wool but as they mature much of this is lost. The radial spines are very numerous, white in colour and somewhat translucent; some plants, however, have straw-coloured radial spines and varieties with this feature are sometimes referred to as M.b.sulphurea. The central spines are variable in number, generally one to six, at first fairly dark brown but becoming paler with age. The white wool in the areoles tends to become discoloured and turn brown with age quite naturally and this should not be taken as a sign that the plant is becoming diseased.

The red flowers are produced only on older plants with any degree of reliability and appear amongst the dense wool in the upper axils of the plant during midsummer. They are red in colour and exceedingly handsome when they form two or three rings round the top of the stems.

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