IT IS the theatrical equivalent of the night-blooming cereus, that most strange of all cacti, which blossoms just once a year and on only one day. A brief spectacle, to be sure, but one you can count on for years, subject to the right conditions and growing methods, of course.

And that's where the analogy ends. For Cherry Red Productions' Day-Old Plays festival, which for five years has forcefully depicted the human drama of creating a play from scratch in 24 hours, will bloom on just one more midsummer evening. Which is to say that as of late Saturday, a curious mix of virtuosic improvisation and spur-of-themoment raunch will be no more.

"We're done," Ian Allen says flatly. Although the festival's artistic director won't rule out "another sort of event-oriented thing" in the future, short-shelf-life theater is not the novelty it once was. Other troupes have gotten into the act with a vengeance, he says, "and I'm happy to leave it to them."

Still, as the Cherry Red folks are the acknowledged day-elders in this burgeoning genre, future impresarios would do well to follow their precepts.

"On Friday at 10 p.m., we all get together: actors, playwrights, directors and production crew," Allen says. "Everybody brings a prop or a costume piece, so we throw all those in the middle of the stage in a pile, and then we take a Polaroid of everyone." At that point, everyone goes home save the producers and the six playwrights, who stay up all night writing a 10- to 12-minute play employing the actors they've just met and the props they've just seen.

No strictures are imposed on subject matter, although Allen notes that "we like it to be aggressive and crazy and sexy and fun," which is perhaps why -- according to the festival's printed rules -- "actors must be willing to strip down to bra and panties if their playwright should write that into their role (no bra necessary if you're a boy)."

The actors rejoin the bleary-eyed playwrights at 9 on Saturday morning, and the whole team spends one indescribable day learning lines, blocking scenes and building costumes, sets and props -- a frantic fight to the finish and an 8 p.m. curtain. The results, as you might expect, are uneven and unpredictable, but the past enthusiasm of audiences leaves the impression that few depart disappointed.

"Beyond all the craziness, there really is some artistry going on," Allen says, "and it's a really great community event." Over the past five seasons, the Day-Old festival (this year's subtitle: "The Final Crust") has culled talent from nearly every theater company in the Washington area, according to Allen. Actors and audiences alike are drawn to the rare flora on exhibit and the equally peculiar growing conditions out of which they spring.

"Sometimes [the playwrights] will write things that are preposterously difficult to stage," Allen says, "but that's okay, because they won't have to be staged more than once. And there's no reviewers to criticize, and no fear that an audience won't like it."

And how could they? For if these shadows have offended, one thinks but this and all is mended: Just hours after birth, these plays' lives have ended.

This time for good, sadly.

The producers, directors, playwrights and actors from Cherry Red Productions' 2001 Day-Old Plays festival. This year's event, in which the group creates plays in 24 hours, is the last.