Everything you always wanted to know about... orchids

So what is it with orchids? Last year, in The Orchid Thief, Susan Orlean treated us to a passionate account of obsession with the exotic flower in the swamps of Florida. Now Eric Hansen reports that the same fixation flourishes all over, from Borneo to northern Minnesota, via New York, Elsinore - wherever the seductive plant can be coaxed to expose itself to the adoring gaze of its acolytes.

An experienced adventurer in the Far East, Hansen was infected with the fever by two enthusiasts who hired him to organise an orchid hunt in the Borneo jungle. From that point, like a hapless hiker sucked into treacherous marshland, the further he delved, the harder it became to escape.

As TV producers have belatedly discovered, there are strong sexual undercurrents to gardening, nowhere more blatant than in the steamy world of the orchid. The very name is derived from the Greek for testicles, inspired by the the two oval tubers that grace many species; and the flower heads can, with little effort, be imagined to resemble other genital equipment.

Hansen stumbled on this early on: "Kinky black hairs, warts, spots, veins, glistening pouches, luscious pink folds and erect columns are what the hybridisers dream of."

The flowers are by no means innocent partners in these erotic goings-on. Their method of procreation has always excited enthusiasts. Some attract pollinators by giving off the same scent as the female of the insect species that does the most effective job on them. By the time the male realises he has been fooled, his rubbing and wriggling has left him coated with pollen to spread to other flowers. An orchid in Madagascar can be satisfied only by a certain breed of giant moth with a 12-inch tongue, penetrating the parts other moths don't reach.

Not surprisingly, the cult attracts some curious followers. Allowed to sit in on a judging session at an American show, Hansen was horrified at the scruffy obesity of the judges, devouring chocolate doughnuts as their "huge hands with pudgy, nicotine-stained fingers reached out to caress the delicate blooms in a way that bordered on the obscene".

In Los Angeles he met an elderly breeder in his "stud room", where he drank bourbon, listened to rock and "had toothpick sex with his orchids". A dealer in Wisconsin spent Saturday mornings lying naked on a table in his heated greenhouse, to a background of New Age music. In some instances, the collector's ardour is so powerful that it fuels violence and death.

This is lively stuff, but the book veers dangerously off course as it develops a crusading theme. Trade in orchids, as in other wild flowers and animals, is controlled by CITES, the Convention on International Trade in Endangered Species. Its primary aim is to prevent unscrupulous operators from digging up rare orchids and smuggling them across borders.

Inevitably, the rules are imperfectly applied. While the illegal trade continues, some well-intentioned collectors fall victim to CITES enforcers, who occasionally launch armed raids on nurseries and confiscate plants. The bereft owners, guilty or not, seldom see their babies alive again.

The orchid growers Hansen meets are rugged individualists who chafe at regulation, unwilling to submit themselves to "bureaucracy". Hansen invites us to join them and him in deploring the heavy hand of officialdom, but gives no proper account of the other side of the story.

Then, in the final chapter, he undermines his case by telling us about a dedicated Minnesota man who, taking the trouble to apply for permits, runs a one-person rescue operation for orchids threatened by road-widening, logging and similar works. From that, it seems likely that the problem is not with the regulator but with those too pesky to be regulated. As a contribution to horticultural politics, therefore, the book is unconvincing - but the sex is good fun.

The reviewer's book 'The Ingenious Mr Fairchild: the forgotten father of the flower-garden' is published next month by Headline