NOT all orchids grow in greenhouses. They grow wild everywhere, probably 25,000 kinds throughout the world. Many are quietly attractive and small, rather different from the luxuriant and exotic varieties seen in expensive florist shops.
About 35 species of lady's slippers (Cypripedium) are native to temperate zones.
But just one species - Cypripedium calceolus - is native to Britain. And it has almost vanished.
To British conservationists, this yellow lady's slipper orchid is a cause cbre, an emblem of the country's rarest plant species. It grows in a single known site in northern England where just one plant - or maybe two - sends up about five flower spikes from underground rhizomes.
This yellow lady's slipper is as appealing as any of Britain's 50 different kinds of beautiful orchids, though it is not the only rarity among them. The British Rare Data Book of Vascular Plants (1983) lists 62 legally protected plants. Nine are orchids.
Several groups are making vigorous efforts not only to protect, but now also to propagate and re-introduce the yellow lady's slipper. English Nature, a government-funded conservation organ- ization, is in the second year of a species-recovery program. This effort concentrates on selected species of both fauna and flora. About British pounds8,000 ($15,000) of the program's British pounds200,000 ($384,000) yearly budget is spent on the yellow lady's slipper.
A cage was placed over it some years ago. A warden camps nearby all summer. The plant's enemies include rabbits, slugs, voles, stock grazing at the wrong season - and sightseers.
Ben Mercer, the local English Nature man, describes how the plant(s) are tended: They are watered in dangerously dry weather, dead material is cleared away in the fall, slugs are killed with pellets, and curious humans are discouraged. Dr. Andrew Deadman, director of the English Nature program, calls the orchid's protection "real gardening stuff."
Humans are blamed for this attractive plant's virtual demise. Victorians collected it for herbariums and gardens, and picked it for market. By 1900, it was thought to be extinct. The present 2-square-meter site was found in the 1930s. Rumors of another site have not been confirmed by botanists.
A few seedlings have shown up in recent years at the site - perhaps seed from the plant that was hand-scattered a decade ago. Yellow lady's slippers develop very slowly.
At the same time, botanists in a laboratory are propagating seed produced by hand-pollinating the surviving plant. Ecological purists insist that reintroduced plants must come only from this known British parent.
The propagation work is being done at Kew, the Royal Botanic Gardens near London. The yellow lady's slipper seeds, the Kew experts have shown, germinate best when still green. A special sowing medium has also been successfully developed from chemical and natural ingredients. Of 18 young lab-germinated seedlings planted at the site, nine are doing well. The numbers may not seem striking, but this amounts to a significant triumph of conservation-by-reintroduction.
Kew's success with the yellow lady's slipper is just one part of a major project, the Sainsbury Orchid Conservation Project, funded by the interest from a British pounds1 million ($1.9 million) private endowment, to develop micropropagation techniques for wild British and European orchids. These are notably hard to grow from seed.
Ironically, it has so far proved impossible to propagate the yellow lady's slipper by the technique being explored at Kew for other orchids.
Based on nature, the symbiotic method used at Kew brings together seeds and a fungus. In the wild, many orchids' seeds (as fine as dust) are known to need the help and nourishment of a specific fungus for germination and growth. Isolating such fungi and using them in the laboratory has made it possible to raise 15 different European orchid species at Kew from seed.
After weaning, some plants have flourished in the great outdoors. The green-winged orchid, Orchis morio, flowered at Kew in its second season and was naturally pollinated. The numbers of this orchid have decreased dramatically in Britain because intensive farming methods and urban expansion have invaded its habitats.
Another orchid, Orchis laxiflora, native to the island of Jersey, has been successfully propagated symbiotically and introduced with striking success in Kew's garden in Sussex. Consequently, interest in symbiotic methods of wild European orchid culture is spilling over into the British horticultural trade.
One commercial grower, Norman Heywood, has 600 plants of Orchis morio well on the way to salable flowering size, and several other wild orchids are developing strongly. Another company with a large established market for wild plants in the public landscaping sector, High Value Horticulture, is interested in Heywood's orchids. In fact, horticultural practices are at the center of wild-plant conservation in Britain today.
Joyce Stewart, director of the project at Kew, points out a further horticultural input. She says, "A number of different Cypripediums we know of in cultivation [are] in people's gardens." They are one source of seed for experiment at Kew. These yellow lady's slippers may have come from plants collected long ago in the wild.
Mrs. Stewart says that DNA testing developed at Kew will eventually determine if such plants are the same genotypes as the existing wild plant. If they are, then plants raised from their seed could be planted into the wild without offending ecologists who fear "foreign genes."
This DNA testing should also determine another salient issue. Yellow lady's slipper orchids still grow in a number of places in Europe. To the eye, they are identical with the English species. But the English variety may have evolved differently. If so, "foreign" material should be kept away from it, the purists argue.
Stewart, however, crisply dismisses such scruples as "absolute nonsense." She says some people are being merely sentimental about the English lady's slipper. She also feels that introduction of varied genetic material could only strengthen the English strain.
The philosophy of reintroducing species for conservation purposes is a matter of debate among botanists. One orchid expert and population biologist, Michael J. Hutchings of Sussex University, while admiring the successes, observes: "Very often when introductions of rare, scarce, extinct species have been tried, they seem to take for a few years and then simply give up."
Dr. Hutchings says conservationists should think more carefully about the strategy for saving specific species. "Communities need to be conserved in the first place," he argues. Management of habitats and slow considered study of such management's effects, he says, is the safer, more lasting method of conservation. He has himself had notable success in one site with the early spider orchid, enormously increasing its numbers quite naturally as a result of effective management.
But, Stewart points out, orchids vary greatly. What works with the early spider may very well not work with the yellow lady's slipper.
Perhaps only time will tell "what works." Meanwhile, small-scale operations such as the recovery of Britain's lady's slipper offer testing grounds where botanists can assess their techniques.
* The 14th triennial world orchid conference and show will be held in Glasgow, Scotland, next spring from April 27 to May 2, 1993.