Pachycereus

As mentioned earlier the Pachycereus species are noted for their particularly strong vigorous growth and for this reason they have been used extensively, where appropriate, as grafting stock for other cacti with weaker root systems which are unable to support themselves. The name is derived from the Greek for fat and alludes to the thickness of the stems of the plants. Pachycereus pringlei is a native of Northwestern Mexico and Southern California where it is one of the dominant features of the landscape. It is possible that in former times vast forests of this plant covered the region but there are now only limited areas of forest left. The plant is extremely important economically and is used to make laths, walking sticks and firewood. The seeds are used by the Yaqui Indians to make a kind of flour which they then bake inlo the traditional tamales of the area. In most collections where this cactus has been grown from seed and kepi under glass all its life the plant is only a semblance of its wild parent. However, it is still extremely attractive and the robust greyish stems are thickly covered with spines, sometimes tipped with black, which sprout from the densely set areoles on the eleven to fifteen ribs that surround the stems. The ribs themselves are flattened and the areoles are so close as almost lo touch each other, and in addition to the twenty-odd radial spines have a filling of brown felt. On younger parts of the plant the spines may sometimes be completely black, but as the plant matures the bases of the spines become paler.

Pachycereus pecten-aboriginum is named after its spiny fruits. The Latin phrase peclen aboriginum means native's comb and the very spiny fruits are supposed lo have given rise to this description although I do not know of any record of Iheir actual use as such being observed. The plant is considerably smaller than P. pringlei and has fewer ribs, normally only ten or eleven. The areoles have a great deal of greyish wool in them (flowering areoles have brownish wool but will seldom be found on homegrown plants) and the spines are rather fewer in number than those of P. pringlei, seldom exceeding twelve. On the other hand the central spines are similar, being of a light grey colour and generally tipped darker. The long yellow bristles which give the plant its name are only produced on the fruits, and these in tum are only produced by older plants.

In addition to the varieties described there is a species called P. columna irajani which resembles P.pecten-aboriginum, and

Backebergia or Mitrocereus clirysoinallus) is also another member of Ihe family which is a worthwhile if less-often-seen addition to a collection. This latter species is distinguished by the dense yellow wool produced on the flowering parts of the plant, particularly round the ovaries, but it is also valuable for its attractive yellow spines which are produced on younger plants.

Setiechinopsis

Trichocereus

Stetsonia

Setiechinopsis

Trichocereus

Stetsonia

Stetsonia coryne is a very spiny tree-like eaetus forming dense groups of columns in North-western Argentina where it is an essential feature of the landscape. In the wild it is a massive plant but because it is fairly slow growing it makes an excellent pot plant as well. The stems are pale green and even young plants quickly develop fairly thick ones: they are surrounded by eight or nine ribs and these are marked by a sort of triangular-shaped notch above the areoles. which are spaced down the sides of the ribs at intervals of three-quarters of an inch (2 cm). The areoles support seven to nine radial spines of varying length, and the white flowers are only produced on well established plants, and seldom, if ever, on pot-grown specimens.

There is a somewhat similar species called Escontria cliiolilla which is sometimes confused with Stetsonia coryne. One of the major botanical differences between them lies in the structure of the scales of the ovary, but as this is unlikely to be a feature of pot-grown specimens in the hands of the beginner we must look for other distinguishing features. E. cliiolilla is generally smaller in habit and has seven to eight ribs and more radial spines, between ten and fifteen in number. The Latin name derives from the fruit which the Indians of Southern Mexico call chiotilla and which tastes a little like a gooseberry when dried.

Setiechinopsis mirahilis is currently included in the Cereeae but may, in fact, only temporarily be there. It is at any rate sufficiently similar in habit lor us to treat it in this section of the book. The plant bodies are very slender and of a curious purplish colour. They seldom exceed three-quarters of an inch (2 cm) in diameter and it is difficult to grow them to any great height. This is not in itself a drawback as they flower freely, even in the second year of growth, and can be raised very readily from seed. The ribs number eleven and are very low. barely conspicuous under the thick covering of bristly, weak, black and white spines. The presence of flowers is indicated in the early summer as the areoles begin to push out dense tufts of black hair and the long tube-like flower stems emerge. The actual flower is while and very slightly scented. Once the bud becomes apparent you must take the plant around with you if you wish to see it flower as this opens at aboul 9 p.m. and is dead by midnight. moreover it develops very quickly and the petals may not be distinguishable even just before it opens. The plants die down very easily and become desiccated, and some authors suggest that this is encouraged if too many flowers are allowed to set seed in any given year. At any event it is extremely advisable to save the seed as and when it is produced to guard against the eventuality of the plant dying off.

Trichocereus pasacanu. on the other hand, is one of the giant species of cacti and comes from valleys high in the hills of Argentina and Bolivia where it can grow up to 30 ft (9 m) in height and looks a little like the saguaro. It occasionally branches from the base but it is more usual for the branches to be formed some way up the stem of older plants. The stems are surrounded by between twenty and thirty-eight low somewhat flattened ribs and the large areoles arc densely spaced along the edges, sometimes being so close together as to touch one another. On pot-grown specimens the spines are extremely variable in size and number, but are generally stiff and yellow. The plant is named after the fruit which the Indians call pasacana and the woody trunks, which become virtually spineless with age. are used as timber in the building of corrals and

Trichocereus pasacana makes excellent grafting stock because of its robust growth and broad stems which enable the graft to take place over a large area of both stock and scion. Also as it is fairly easy to obtain specimens of the plant there should be no difficulty in finding a replacement for a plant which has been used in this fashion. In its native Argentina it grows on exposed cliffs and hillsides and thus it is fairly tolerant of low temperatures in the winter and appreciates a certain amount of dryness

Tricliocereus spacliianus and T. santiaguen-sis are, in fact, the same species although the columnar in growth but older plants will eventually form branches near the base of the stem. The stems themselves are mid-green and as they mature they become almost yellowish, giving the appearance of a golden trunk. The number of ribs is extremely variable although most cultivated specimens seem to have between ten and fifteen. The size of the ribs varies loo from plant to plant, some having very shallow, barely visible ridges and others having prominent, quite conspicuous ones. The spines are at first pale yellow bul as they mature they turn brown and ultimately become quite white. The radials are normally nine in number but they can be very

They surround a solitary central spine which is a little longer. The white nocturnal flowers are only produced on much older

Tricliocereus werdemannianus is another extremely variable species produced probably as the result of natural cross hydridiza-tion as there is little prospect of pot-grown plants flowering. The plant bodies of this species are at first globular bul elongate from the third or fourth year onwards to assume a more characteristic habit. There are about eleven ribs surrounding the pale green plant bodies although there are some forms with more ribs and stouter spines which are probably related to T. chiloensis. The spines, as with T. spachianus, are extremely variable - the plants with stouter spines probably being forms of T. chiloensis. The most important distinguishing feature of T. werdemannianus is the comparative closeness of the white areoles.

As already mentioned T. chiloensis is very similar and several forms of it have been given Latin names. T. c. eburneus has white spines while those of T. c. spinosissimus are brown and are bent backwards so they point upwards round the sides of the stems. In T. c. panhopliies the spines are very nearly black in colour.

Plants with very slender almost needlelike spines are probably more closely related to T.poco. especially where they arc dark brown when young and form a dense covering round the ribs of the plant.

Of all the upright cereus. the Eriocerei are some of the most rewarding to grow. They are vigorous plants and for this reason are frequently used as grafting stock for varieties which do not do well on their own roots. Eriocereus jusbertii can be induced to flower when only five years old at a height of about 2 or 3ft (60 to 90 cm). The stems are dark green with a tinge of purple in them and are surrounded by between four and six ribs in commercial specimens. There is a curious difference between imported plants raised from seed and those which are struck as cuttings, the former adopting their characteristic upright habit only later in life whereas plants taken from cuttings start growing upright straightaway.

In addition to flowering freely E. jusbertii also has the advantage that the spines are quite small, being produced together with a certain amount of wool in the areoles. which are set on the sides of the ribs at intervals of just under an inch (2-5 cm). The flowers are very large and worth waiting for. greenish yellow in colour and over 6 in (IScm) in length.

Eriocereus marlinii is another variety which is frequently used for grafting but is not so floriferous as the previous species. It differs in having the areoles set upon quite prominent tubercles and in having much longer spines. There is some confusion in the trade between harrisia and eriocereus. both names being used more or less indiscriminately to describe the same plants, although they appear to be two quite different genera in the wild.

Eriocereus

Wilcoxia

which can easily be distinguished by its extraordinary dahlia-like root system. It produces a series of tubers below the ground and has weak sprawling shoots which may need staking. W. schmollii is normally sold as a grafted plant since its tuberous roots are more suited to the open sandy soils of the areas of Texas and Mexico in which it is native, and under cultivation it tends to develop somewhat thicker stems. The stems are very dark green, almost purple, and as they grow older the basal part becomes yellowish. The stems are up to half an inch (I cm) thick and carry eight to ten low flattened ribs with fairly dense areoles which support some weak bristly spines, the radial ones numerous and white and the central ones solitary and black, and a large number of hairs which appear to be extensions of the spines. The hairs seem to grow more densely as the plant gets older.

In spite of its apparent need to be grafted it is an excellent plant for the amateur and when quite young produces a most attractive pink flower with a green-lobcd stigma. It was probably partly on account of this green-lobed stigma, which is a feature of the Echinocerei, that is was originally called Echinocereus luberosus senilis.

Wilcoxia poselgeri, although quite capable of being grown on its own roots, is a rather weaker and generally more slender plant. It becomes completely spineless with age and the ribs are almost inconspicuous and normally number about eight. It deli-

Uruguay. Paraguay and Argentina where it forms branching clumps of upright stems up to 6 ft (2 m) in height. It is faster growing than the following species and distinguished from it by the very much less dense covering of spines and by their yellow colour. The stems themselves are dark green with twelve to sixteen low obtuse ribs. The areoles are densely packed along the edges of the ribs, and are often practically touching one another. In addition to the twenty-odd spines that come out of each areole there is a quantity of dark brown, almost black, felt. The flowers of this variety, like those of the following one, do not really open and the name is derived from the Greek word meaning shut. They can be produced on a specimen which is 2 ft (60 cm) or more in height with no great difficulty and this makes it a valuable addition to the collection, particularly as the flowers are a good red colour and contrast well with the yellowish spines.

Many of the plants which are currently offered for sale as C. slraussii are, in fact, a variety of this known as C. s.jujuyensis. Like the preceding species it forms clumps from the base of the plant but young plants do not send up fresh stems as readily as C. bau-rnannii does. The stems are not as dark as the preceding species being more of a mid-green and are slightly thicker with many more ribs, often up to twenty-five in number. The spines are inconspicuous and are almost hidden amongst the long white hairs which are produced with the spines from the almost adjacent areoles. The species is particularly pleasing in that one can run one's lingers up and down the lower parts of the stem with impunity, so it is an attractive plant to handle as well as to look at. Sometimes up to four central spines are produced on the young growth near the top of the plant, these are frequently yellow but some forms of the plant have pure white spines. C. s.jujuyensis differs from the illustrated species in having fewer hairs and rather longer spines, moreover the spines are more perceptible and are a much darker yellow, sometimes even brown.

Cleistocaclus smaragdiflorus is another species often found in the shops. This has only twelve to fourteen ribs, and more erect spines which are densely packed round the stem. The main botanical difference between this latter species and C. baumannii is the shape of the flower tube: the latter having a curved one and the former having a straight one. Faced with a choice between the two 1 would generally recommend C. baumannii as being the faster growing and more readily flowered.

•vS^W&te' Cephalocereus pal-eri

•vS^W&te' Cephalocereus pal-eri

Cephalocereus

Haageocereus comprises a number of very attractive species which are chiefly remarkable for their highly coloured spines. The varieties available can be divided into two categories depending on the thickness and coarseness of the spines. Of the group with slender spines Haageocereus chosicensis is by far the most common species in cultivation today, and is distinguished by its strongly coloured yellowish spines from the other variety which is often seen - II. versicolor. The Latin name of the latter refers to the rainbow-like markings on the spines. The plant forms columns with slender stems each surrounded by about sixteen dark green low ribs and the spines, which range in colour from reddish brown through to orange, are produced in large numbers from the closely set areoles. the central spines pointing slightly upwards. In their natural state in Peru the species belonging to this genus form plants about 4 fl (1 -23 m) high. Plants imported from the wild may have quite different coloured spines from home-grown plants of the same species.

The second group of Haageocereus is characterized by coarser spines and one of the main types found in shops - H. acran-ihus - was once probably called Bingliamia acranlha. This species has thicker stems, up to 3 in (8 cm) in diameter, and fewer ribs, normally not exceeding fourteen in number. These species also tend to produce yellowish hair at the areoles as well as the spines. Some varieties have spines with a slight purple-shade to them, most notably H.olovins-

Cephahcereus palmeri is, to my mind, a more rewarding cephalocereus to grow than the more frequently found C. senilis which is illustrated beside it. It is considerably faster growing and the stems with their many fewer ribs, numbering seven to nine, are more clearly visible, while the bluish tinge of the young growth can also be observed. In Eastern Mexico, where it grows wild, this species attains a height of nearly 20 ft (6 m) and carries numerous branches. The most pronounced feature of the plant is the abundance of long white hairs produced all the way down the ribs from the areoles. which are well hidden by the hairs and normally set fairly closely together, often only half an inch (1 cm) apart. Beneath the hairs there are about ten radial spines. As the plant matures and grows taller the hairs at the base will start to disappear.

Other varieties of Cephalocereus which are similar to the species illustrated are C. sariorianus. which differs in having fewer spines on the younger growth, seldom more than eight in number, and in having more distantly spaced areoles. and C. leuco-ceplialus which has up to twelve ribs and long wool. C. chrysacanihus is distinguished by its yellow spines.

Cephalocereus senilis is well known as the old man cactus, and fulfils one of the commonest prejudices against cacti in that it is immensely slow growing; however, it is a popular species on account of the long white flowing hairs that completely cover the v ribs and closely set areoles. where the plant may be ex-and grease in the atmosphere it is a good idea to wash the long hairs occasionally in a mild solution made of soap flakes and water. The hairs can then be combed out and the plant stood in a sunny location to dry, otherwise the hairs can become very matted and thoroughly unsightly. As stated earlier the plant is very slow growing and it is unlikely that cultivated specimens will ever flower. Specimens may be encouraged to grow a little faster by grafting them and such plants are often sold in the shops. Unlike most other cacti, C. senilis does not develop the slightly woody trunks and this makes it especially prone to attacks of basal rot fungi such as rhizoctonia; grafting on to a stronger-growing rootstock such as Trichocereus will help to avoid this.

A similar species with shorter hairs and longer spines is C.hoppensledlii. now frequently sold as Hasellonia lioppensledlii.

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