Breeding new succulents

"Every plant does not produce a seed similar to that from which it is sprung; some produce a better seed, others a worse." This quote from the same ancient

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source that provides the chapter headings used here may be taken as the birth certificate of plant breeding. A hybridist can achieve in one lifetime what might take millennia if left to nature. He can speed up evolution, bringing togetherand crossing plants from widely separated localities, and can even open up quite new sources of variability by direct attack on the chromosomes with drugs, irradiation and other sophisticated laboratory techniques. Such methods are routine in breeding cereals and other crops, but little has yet been done with succulents. Indeed, some growers are actively opposed to the creation of novelties. Are there not enough species already? Yes, but in all spheres of horticulture hybrids eventually replace species, being better adapted and selected to suit the needs of man. By all means let us conserve the wild species of succulents, both in their habitats and in botanical gardens and specialist collections; as more and more habitats are destroyed, the onus is upon us to do so. But in private collections grown purely for aesthetic appeal, good named hybrids may have more to offer than some species, and deserve their place (8.3,10.2). Attractive novelties such as the dwarf aloes or astrophytums win converts at first sight, and incidentally lessen the demand for yet more imported plants from habitat.

The most spectacular results so far in breeding succulents come in the group I call "epicacti", from the fact that their ancestors are mostly epiphytic tropical forest cacti of the genera Nopalxochia, Epiphyllum, Heliocereus and allies. Not least remarkable here is the ease with which species of different genera can be interbred and the hybrids still retain a measure of fertility—a situation unmatched elsewhere except among the orchids. The epicacti are not much to look at as plants: their flat, green, almost unarmed stems (not leaves!) remind one more of the aspidistra than of a cactus. But during the short period when they a re in bloom in early summer they are without rival (5.11, 12, 8.4 ). The great funnel-shaped blooms of classical simplicity and form come in white through shades of pink, orange and magenta, often enlivened with a steely blue flush—a character inherited from Heliocereus sped-osus. They are the finest flowers in all succulents. Indeed, it would be hard to name any bloom that surpasses them in combining brilliance of display and deli cacy contrasting with the solid earthiness of the stems that bear them.

Other groups where great advances have been made by the hybridist are the genera Aloe and Sempervivum. Both now have their own specialist societies, with facilities for testing and recording the latest introductions.

As mentioned earlier, prospective hybridists can profit much and save useless effort by a knowledge of the genetical background to the plants on which they work. For instance, in the example of Portulaca given above, we saw that diversity appeared only in the second generation; all Fi plants were identical. Thus it is desirable to go to the second generation, if that is possible, to begin to see the full potentialities of a breeding programme. Whereas many F2 plants should be raised, only a few of the Fi are needed because all are alike.

Epicacti the floral glory of the cactus Family. Like orchids, they are intergeneric hybrids of complicated ancestry descended from mostly tropical climbers or epiphytic species of at least five different genera Right (5. If) is 'Eden'. Below(5.12) is 'Carl von Nicolai:

Growing Succulents for Pleasure

There is no shortage of published guidance on how to grow succulents, both in popular handbooks and in the current journals of the various specialist societies. I shall not set out to repeat what has been said many times; rather, the emphasis will be on seeking the reasons behind such advice, because it is always better to understand principles rather than blindly accept dogma. It can be argued that cultivation is an art and cannot be taught. Even experienced growers are forever learning, and if one were to tell me he never lost a plant. I shouldn't believe him. Some books go into great detail on the niceties of how and how not to grow succulents. Comparing them reveals occasional contradictions. which is to be expected when much of what is said is based on personal faith rather than on scientifically proven facts.

There has been woefully little research on succulents, and most of the recommendations on how to meet their needs in the highly artificial environment of a glass box far removed from their native home comes from analogy with work on other, non-succulent plants — mostly agricultural and horticultural crops. In the 1930s the John Innes Horticultural Institution at Merton, in the London area, pioneered research into glasshouse construction and the formulation of standard composts. But a soil mix that suits annual glasshouse mesophytes may be less than ideal for succulents that may go two or more years without repotting, and similarly an insecticide developed for cucumbers may not suit Crassula and Lithops. Thus, although we can be thankful for a wealth of technological advances, from the polythene bag and systemics to methods of seed storage and meristem culture, we are nevertheless left to adapt these general techniques to the special needs of succulent plants.

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