TO THE PETAL WITH METTLE; FLOWER HUNTERS SCOUR THE STATE FOR THE OAKLAND MUSEUM’S ANNUAL MOTHER’S DAY SHOW

They fan out in pairs, a posse of sports utility vehicles, pickups and vans. In two days, working sunup to sundown, they must track down and bring back their quarry.

The one riding shotgun eyes the roadside. At a moment’s notice, the driver blessed with a Caltrans permit pulls to the shoulder. They leap into action. One pulls out containers, water and other supplies. The other starts to pluck.

They are hunting wildflowers.

Every year, a half-dozen botanists gather the material for the Oakland Museum’s California Wildflower Show, which takes place this weekend. Their stalking grounds can extend from the rocky coastal bluffs to the prickly, dry desert. They trek through mud, scramble up rocks and wade through fields of lupine.

“Usually most of the collecting is done Wednesday and Thursday. Friday is our panic day,” explains Christopher Richard, the museum curator of aquatic biology.

For this 32nd go-round, they’re covering Northern California blooms in conjunction with the exhibit, “After the Storm: Bob Walker and the Art of Environmental Photography.”

Romantic visions aside, the task of collecting 150 to 250 species can be unpredictable. Richard says they may hit the mother lode, but more likely it’s drive-by pickings: “Ten minutes, grab frantically, then hop back into a pick-up and head out.”

Gatherers must record the locale and other details for identification. They must not overcollect, mix their flora, or choose endangered or rare species. They also try to avoid unpleasant encounters with spiny gooseberries and nettles.

The cut is done quickly and cleanly. Stems of delicate species with milky sap might be singed shut with a lighter. Plants from warmer areas are kept dry, whereas blossoms from redwood forests need a good misting.

Some botanists have devised different formulas to prolong a flower’s life, from a few drops of bleach (to kill rot organisms) to 7-Up (for sugar and slight acidity). A wilting flower can be administered a shock treatment: a hot-water plunge, followed by a cold-water soak.

The ideal collecting conditions are cool, moist and overcast. “On the one hand we were blessed; April was wet,” Richards says, but then, “It has been so hot last week.” Scoping lilies and calicorts on north-facing slopes might be more fruitful than combing burnt-out grasslands for poppies and lupine.

On Friday, all involved convene at the museum to sort plants, arrange them in vases and verify the species. The art of the bouquet, says UC Botanical Gardens museum scientist Jerry Parsons, is “very naturalistic, nothing you’d see out of a floral shop.” The array is the floral habitat in microcosm, with mushrooms, lichen, shrubs, flowering herbs or bulbs.

Parsons, who attributes his aesthetic to his Portuguese gardening grandmother, spends less than an hour on each of the larger displays. In all, the eight or so arrangers assemble 150 to 250 bouquets.

Despite temperamental branches or drooping blooms, the annual showcase is far less nerve-wracking for the top wildflower tamer than the one wedding he did for a co-worker’s daughter.

As ephemeral as well, nature, the show lasts just one weekend, but draws about 3,500 visitors. They come to admire the splendor of the outdoors indoors, few realizing the wrangling it takes to re-create such beauty.

“The biggest thing is the determination,” Richard says of the wildflower hunt. “It’s being aggressive.”

Vera H-C Chan is the Times event editor. She can be reached at 925-977-8428 or at vchan@cctimes.com

Preview

What: 32nd Annual California Wildflower Show

Where: Oakland Museum of California, 1001 Oak St., Oakland

When: 10 a.m.-5 p.m. Saturday, noon-5 p.m. Sunday.

How much: $6 general, $4 seniors and students, free ages 5 and under

Call: 888-OAK-MUSE (625-6873), www.museumca.org