"In the next month, the forest floor will reach its maximum temperature," says Paul Engman, a naturalist with Riverbend Nature Center in Great Falls, Virginia, to a hodgepodge of expert and amateur wildflower seekers.

But right now, the forest we're standing in looks the way we all feel: cold. The trees are leafless, the ground is brown, the trail is marked with last year's dried-up seed pods and crackly brown leaves.

And yet, under Engman's guidance, a small miracle is revealed: a tiny white flower, speckled with deep purple -- a grace note heralding spring's advance. "This is called 'harbinger of spring,' " he says, "but it's also called 'salt and pepper' because of its coloring."

White is a popular color with wildflowers this time of year, from the daisy-like bloodroot with its eight white petals to a tiny dewdrop of a flower called spring beauty.

This latter bloom, which dots the park right now, looks like a how-to manual for pollination. "You see these pink stripes on the petals?" Engman asks. "They all point toward the center where the pollen is and act as a directional for insects."

And if insects should bypass this bloom, the naturalist points out, there are "a bunch of buds down below it, each of which will bloom in turn" to attract other, later insects.

Spring beauties are native to the Washington area, but Riverbend, Great Falls and Dranesville District Parks all contain many "foreign" flowers -- travelers along the Potomac from West Virginia and Pennsylvania. That explains, for example, the presence of ramps -- wild leeks with long, flat, green leaves -- that crop up in the flood plain.

"Every year in West Virginia they have a ramp festival, and you better be prepared to eat ramps if you go," Engman warns. "They're pretty good -- once they're cooked.".

He tells the group to resist the temptation to dig up a few for a salad. "It's illegal to pick anything out of a public park," he emphasizes.

And unless you're prepared to transplant what you're picking, taking wildflowers from any other site is probably not a good idea, says Barbara Stewart of the Virginia Wildflower Preservation Society, who came along for the walk.

"Most wildflowers will die as soon as you pick them," she warns, "and many are difficult to transplant. Lady slippers, for example, have to have a special kind of mold in the soil to grow, so most people have no luck transplanting them."

Her organization does some "rescue work," she says, removing wildflowers from areas under development and depositing them at Fairfax's new horticultural center (at Green Spring Park) or the American Horticultural Society's River Farm near Mount Vernon. "But mainly, we just try to get the message across not to trample on flowers or pick them."

But our guide got his start picking groundpine and selling it for 14 cents per pound when he was a teenager, he admits. "Now, the plant is overcollected for Christmas decorations," he says.

Collecting for crafts may be the modern scourge of wildflowers, but Engman knows several plants that were collected in earlier days for their medicinal properties. One is a lovely purple flower that fascinates children. "It has a fuzzy stem that feels like a caterpillar," he says. Its leaves are shaped and colored like kidneys, so the hepatica was thought to have curative powers over kidney disease.

Apothecaries also esteemed saxifrage, a delicate white flower whose roots break up the rocky ledges where it grows. The medicine men of the day thought it would have the same ability to break up gallstones, a theory that has not been borne out.

Gallstones and kidneys aside, the wildflowers seem to have at least one curative power, says Stewart. "They restore your soul," she says, pointing to a clump of blues- chasing Virginia bluebells.

"In this area, there are so many activities competing for our time that it's hard to attract people to simple walks in the woods," she says. "But a morning out can do marvels for your psyche."

And for your mind: In the hour and a half most wildflower walks take, the rank amateur can learn to recognize at least a dozen wildflowers. It's a painless way to learn. A WALK WITH THE WILDFLOWERS Wildflower walks and talks abound in April and May. The public is welcome at all the following, including children, though Engman warns that those over six tend to do best on the one- to two-hour hikes. APRIL 9 --10 to noon. C & O Canal. Meet in the parking lot across from Angler's Inn. Sponsored by the Audubon Society. 652-5964. APRIL 13 -- 10 to 11:30. Riverbend Nature Center, Great Falls, Virginia. 759-3211. APRIL 17 -- 2. Bull Run Regional Park. Bluebell walk. Meet at the swimming pool parking lot. 631- 0550. APRIL 17 -- 1 to 3. "Learning Spring Wildflowers," a family-oriented program for age eight to adult, sponsored by the Audubon Society in Chevy Chase. Participants must preregister. Admission. 652-5964. APRIL 19 & 26 -- 9:30 to 11:30. "Spring Wildflower Workshop," Long Branch Nature Center, 625 South Carlin Springs Road, Arlington. Free, but you must preregister. APRIL 20 -- 10 to 12. Dranesville District Park, 7400 Georgetown Pike, McLean. 759-3211. APRIL 23 -- 10 to 11:30. Lake Accotink Park. 5660 Heming Avenue, Springfield. 451-9588. APRIL 24 -- 2 to 3:30. Hidden Pond Nature Center, 8511 Greely Boulevard, Springfield. 451-9588. APRIL 26 -- 10 to 11:30. Lake Accotink Park. MAY 1 -- 2 to 3:30. Royal Lake Park, 5344 Gainsborough Drive, Fairfax. 451-9588. MAY 5 -- 10 to noon. Dranesville District Park. MAY 5 -- 12 to 12:45. Lady slippers at Hidden Oaks, 4030 Hummer Road, Annandale. 941-1065. MAY 8 -- 1 to 2. Lady slippers at Hidden Oaks. MAY 8 -- 2 to 3. Lady slippers at Burke Lake, 7315 West Ox Road, Fairfax. 451-9588. MAY 8 -- 2 to 3:30. Ellanor C. Lawrence Park, 5040 Walney Road, Centreville. 631-0013. MAY 21 -- 7:30 to 5. Excursion to Shenandoah National Park. Meet at Annandale Community Park, 4030 Hummer Road, Annandale. Transportation provided. $15. 759-3211.