One of the movement's leading figures is Theodore Roszak, coiner of the term ecopsychology, author of ecopsych bible The Voice of the Earth and professor of history at the California State University. Prof Roszak does not see anything strange in quizzing patients about their feelings for ferns or attitude to acacias.
"Back in the Sixties the prominent Scottish psychiatrist RD Laing was considered highly contentious when he included family background in the diagnosis of neurosis or psychosis," he says. "It was a real struggle to get psychotherapists to realise people go crazy because they live in a crazy-making environment called the family, but now that's accepted. The next step is to include the natural environment. Relationships with the family can be dysfunctional, and relationships with the environment can be dysfunctional too."
But surely most people are quite keen on nature, even if they don't see much of it? "Many people see nature as hostile, cold, devious," says Professor Roszak regretfully. "If people have no relationship with nature, the world will become mad, and we won't even recognise it as mad," he adds alarmingly. "If we don't bring up children with a healthy relationship with real nature - not television documentaries, not Disneyland - they will be brought up in conditions injurious to their sanity."
Isn't all this a bit, well, Californian? "Anything from the west coast of the States, people think is flaky - in fact it's the wisdom of the ages. It's common sense: if you lock people up in an urban environment they will go crazy."
Yikes! So how do the ecopsychs address the case? Initially, says Professor Roszak, a therapist might encourage a patient to visualise "rewarding experiences in childhood with plants and animals". Other therapists may prescribe walks in the park, gardening, writing angry letters to large, mean, environmentally unfriendly businesses, cutting consumption or starting to recycle. More strenuous regimes include "wilderness treatment" - heading into the woods, sometimes for weeks at a time - or even a form of shamanism: patients may learn to get in touch with "animal ancestors" for advice.
Sarah Conn is an ecopsychologist who teaches at the highly-respected Harvard Medical School. "Ecopsychology is the study of the human psyche in the context of the larger systems of which it is part," she explains. "It aims to promote sustainable relationships among humans and extend to sustainable relationships with the more-than-human world. We want to redefine sanity, revise the practises of psychotherapy and ideas of mental health - that's our mission. We ask: how is the earth speaking through this symptom?"
This can bring up some big issues. "Fear of pollution, destruction of the environment, crime and hunger are all very much a part of what people bring." So how to tackle these deep anxieties? Her initial approach might be to "go out, go for a walk, look for places they can connect - a garden, a park, even grass growing up through the sidewalk."
The next thing is to confront your global fears and tackle them bravely. "If people get mobilised and get through their feelings of despair and anger, the new definition of sanity is engagement," says Ms Conn, who might suggest taking action by starting up a neighbourhood ecological action group.
Some therapists whose urban bias is too deeply ingrained remain sceptical. One woman found that when she tried to tell her former therapist about her depression over pollution, she was cut off in mid flow. "She told me I was using the ecostuff to skirt the real issues - like why I didn't have a boyfriend," complained the aggrieved client. She now walks five miles a day in the park, saying good morning to her favourite waterfall en route, having found a sympathetic ecopsych.
Others can be harder to convert. "I was talking to a group of stress managers," recalls Prof Roszak. "One of their techniques is to ask people to visualise things that relax them. I said 'Do you ask people to visualise urban streets, football stands, shopping malls?' Of course not - they use woods, natural places! It's simple. The world we live in drives people crazy and we need to get out. One of the stress managers had the candour to say 'Well, if we told people that, we wouldn't be able to charge them.' "
8 'The Ecopsychology Newsletter', Box 7487, Berkely, California 94707, USA. 'The Voice of the Earth', Bantam, pounds 5.99Reuse content