Boyd Webb might be called an extra-rational ecologist. He is, in his peculiar way, a fighter for the earth. And wonder is his weapon. His wry-but-righteous photographs deliver weird pro-planet sermons. They're part preachy, part preposterous. Thirteen are on view at the Hirshhorn Museum and Sculpture Garden, and they're very strange indeed.

Few other Issue Artists are as idiosyncratic, but down deep he's not kidding. His every picture tells you that this 43-year-old Londoner, New Zealand born and raised, is a man who hates pollution, the despoliation of the habitat, the corruption of the seas. But Webb's giant colored photographs are too quirky and fantastical to ever be employed as propaganda posters by Greenpeace.

His plots are far too loose. His stage mechanics clunk. But even those impatient with big and glossy photographs coming on as paintings may find his works beguiling. First they make you grin, then they make you worry. Webb's sermons are protected from sanctimoniousness by goofiness, and from goofiness by rage.

Instead of "Save the Whales," Webb chooses to depict the whales saving us. His picture is called "Nourish" (1984). A young man in drenched trousers is being suckled by a whale, or what seems to be a whale. Look closer and you'll see that the artist's gray leviathan is a mass of foam-backed carpet barnacled with puckered dried East Asian plums. What is going on here? That's a question one asks often when looking at Webb's art.

The big picture he calls "Croup" (1988) takes smoke-smog as its subject. "I'd seen a television program about beagles being taught to puff on cigarettes," said Webb the other day. Or partial explanation. There are no beagles in his picture. Neither is there smog. What we see, instead, is a sheet of fog-gray plastic through which poke the squashed-in heads of 28 small ducks. The ducks aren't real either. They're uninflated blow-up Chinese plastic toys. Deconstruct this picture, and you'll find yourself confronted with a few bits of cheap plastic, and yet Webb has somehow conjured up a strangled phlegm-filled cough.

His messages are mixed. So too are his devices. To say that Webb takes pictures of stage sets in his studio is to understate his methods. He's not just a photographer. He's a scavenger, a sculptor, a performance artist of a sort, a special effects conjurer (of a distinctly low-tech kind), and a trickster too.

Most photographs feel real, we believe them when we see them, but Webb employs his camera -- skillfully, subversively -- to make his viewers doubt. His starry skies are plastic, his earths are made of carpet, his seas are painted paper, his moons are paper too. Webb's inexpensive props -- his dried plums and his Chinese toys, his postcards and his rubber teeth -- subvert photography's veracities. But he deceives to evoke truths. And then his truths slide into dreams.

It is his managed mix of doubting and believing, of cheap, coarse plastic facts and science fiction evocations, that gives his art its unfamiliar character, its ripe surreal spirit.

Two vast paint-splattered jellyfish, men-of-war with tentacles and odd translucent bodies -- each containing newborn twins (this time real twins) -- drift off in opposite directions on glowing plastic seas. Or: A compacted mass of zebras -- a chrysalis? a lollipop? -- dreams a dream of zebra freedom. Or: A human monster underground, beneath a parsnip-studded field, puffs up a balloon that explodes the dwellings overhead. How can one explain these dark and mournful images? The answer is: One can't.

Webb has said, "I think an artist produces his best work indirectly, without truly realizing what he is making. The work seeps out, deciding for itself when it is complete. It is like juggling a lot of cats in the air at the same time -- at the right moment they form a rug."

Much about Webb's work -- both the scale of his prints and his theatrical reliance on fictive studio setups -- calls to mind the work of many other artists. As the exhibition's curator, the Hirshhorn's Sidney Lawrence, notes, "Cindy Sherman's chameleon personae, William Wegman's dress-up dogs, Bernard Faucon's picnicking mannequins, Joel-Peter Witkin's brutalized Victorians, James Casebere's monochrome blockhouse cities, and Sandy Skoglund's animal nightmares are all variations within this genre." So are Robert Cumming's mind games. Equally familiar -- one thinks of Edward Kienholz here, of Tony Cragg and of Bill Woodrow -- is the way he uses urban junk to spin fantastic narratives.

Victorian English painters, many of the best of them moralists at heart (Alma Tadema, the pre-Raphaelites), loved the focused conjuring of distant worlds. Webb, despite his camera, is in some ways their descendant. He sometimes seems a distant cousin of Monty Python too.

His work is slightly slight. But it's also deeply personal. His one-room exhibition is one of the series of "Directions" shows devoted by the Hirshhorn to contemporary artists. It closes Jan. 27.