The Cactanae has always seemed to me to be a special group of cacti. It consists of a genus called Melocactus all of whose thirty or so members are somewhat rare in cultivation. In spite of this rarity the best-known for itself the epithet of Turk's head cactus. As a genus they are characterized by a red woolly cephalium which forms on the top of the plant just before flowering commences but the plants as a group are slow growing and this feature does not develop until the plant is several inches in diameter. Another curious feature of these plants is their preference for coastal regions and because of this they were some of the first cacti ever seen by Europeans.
They are generally rather delicate plants and tend to need rather more warmth in winter than other cacti in spite of their hardy appearance. If you have a greenhouse it is probably worth investing in a maintain at least a part of the greenhouse at a slightly higher temperature if you wish to tackle some of the rarer species of which this group is typical. They can be grown as grafted plants with some benefit as this tends to make them grow faster than they otherwise would and enables them to tolerant of neglect or low temperatures.
When the plants are young it is difficult to distinguish them from any other group of globular cacti but for the sake of completeness and accuracy 1 have shown them separately and devoted a page to them.
Melocactus oreas makes a round globular plant with eight broad low ribs running together at the base so as to be virtually indistinguishable. The areoles are set in recesses on the sides of these ribs about half an inch (I cm) apart and in addition to producing a small quantity of whitish wool when young they bear between seven and eight radial spines, the uppermost of which is generally very much shorter than all the others. These radials vary between nearly 1 and 1J in <2-5 and 3-5 cm) in length, the longer ones being on the lower part of the areole and basically straw coloured but lipped brownish red and bent over slightly at the lips, although they are by no means hooked. The younger spines are very much browner, almost purple in colour, and the radial spine which will ultimately become the lowest one is very much darker than the rest. I have never seen this species in flower but it no doubl produces the woolly red cephalium so characteristic of the group. Like M. ile morro chapensis il is rather more tolerant of neglect and rather stronger growing than many of the other species.
Melocactus de morro chapensis is rather paler green than ihe preceding species but has the same globular habit which it maintains throughout its life. It has about thirteen broad ribs but these are not quite as obtuse as those of M. oreas and are distinguishable even at the base of the plant. The radials and centrals, like those of the previous species, are recessed in areoles in notches in the sides of the ribs and like the preceding species Ihe radial spines are generally eight in number although the upper one is not conspicuously shorter than the others. They are of a similar straw colour to those of M. oreas but are not nearly so strong, being probably only half as thick, and have the feel of stout bristles rather than thorns. The lower spine on the of the preceding species attaining a length of nearly 2 in (5 cm) even on quite young specimens.
The areoles are felted and the young spines are rather more brownish than purple, the colour persisting longest on the solilaiy central which remains brownish even after the others have turned straw
Melocacti arc uncommon plants and can be recommended as something to strive for: however, they have little attraction when young apart from their rarity. Imported specimens which have already developed sufficiently in size to form the red woolly top arc difficult to re-establish in Britain in a greenhouse except under the most favourable conditions and they are for this reason a plant for the connoisseur rather than the
The Coryphanthanae Coryphantha
The Coryphanthanae is distinguishable from all the other major cactus groups so far discussed by the production of (lowers from between the tuberculate areoles rather than from the areoles. However, because young plants of Tlieloqactus resemble mammil-larias for quite a while, 1 have also included this genus at the end of the section on Coryphanthanae. Because of the relative unimportance of the number of rows of tubercles most books do not try to enumerate the spiral rows or use this as an identification. A more important feature is the actual shape of the tubercles when viewed independently, whether they are cylindrical or polygonal or rhomboidal in shape.
They are generally tolerant plants growing well on their own roots although a few species, notably Mammillaria plumosa and M. schiedeanu, are a good deal easier to grow when grafted. This may have as much to do with the rather weak texture of their tubercles, and the fact that water can lie around and breed infection in them when they are grown at ground level, as with the structure of their root systems.
For ease of classification most of the authorities divide the genera into two groups, those with a milky sap and those with a watery sap. I have followed this practice and if you are currently holding the book in one hand and a plant that you suspect belongs here in the other, get a pin and prick the plant. If the sap produced is watery the plant belongs to the group described on pages 150 to 157. If on the other hand the sap is milky you should turn to pages 157 to 160.
Before coming to the mammillarias which constitute the bulk of the group I should mention two attractive members of the type genus itself. Coryphantha clava is a fairly fast-growing plant which, although at first globular, rapidly elongates and becomes cylindrical. The plant bodies are greyish green and ultimately can attain a height of a foot (30 cm) or so, making il one of the larger members of the group. The upper tubercles have a certain amount of wool in the crevices between them but this is not a reliable indication of bud formation as it is with some members of the group. The radials are nine or ten in number, generally straw coloured and produced from areoles which, like the crevices between them, generally have a little wool at first which disappears with age. The centrals are usually solitary on cultivated plants, are brown when young but become straw coloured like the radial spines as they mature. Although fast growing, C. clava can hardly be called a lavish llowerer and plants normally have to attain a height of 6 in (15 cm) or more before there is any real chance of seeing the large glistening yellow flowers.
Other species of Coryphantha offered for sale are C. pallida, which has bluish-green low globular clump-forming plant and has many more radial spines, normally twenty in number and white in colour, and C. radians with about fifteen radials and mid-
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