Take a Hike

SAT 4/26

Mount Tam's annual Wildflower Hike isn't exactly a tiptoe through the tulips -- it's late in the season for tulips, which aren't indigenous to California, anyway. It's more of a traipse along the trailhead, a moderately paced, five- to seven-mile traipse, banked by delicate purple lupine blooms, flame-colored California poppies, and cheery botanical cousins the creamcups, suncups, and buttercups (the last of which have inspired scores of great, and frankly not-so-great, poets).Orchids also grow wild on the mountain, including, says volunteer hike leader Bill Stevens, the calypso orchid ("A miniature version of what you'd get at the prom") and the choral root orchid, with a small stalk swathed in tiny blossoms. Stevens and a group of six to 10 botanists preview the hike the day before to put stakes next to what's blooming (spring sprang earlier than usual this year) and to draft a guide for hikers that helps identify the 60 to 80 types of wildflowers growing on the south side of the peak. Roughly 50 to 75 people join the hike each year; they're split into smaller groups, assigned a botanist, and given the guide, which features numbered entries that correspond to the staked flowers.

Hikers are advised to dress in layers, wear sturdy shoes, and bring lunch and water. The trek runs from 9:30 a.m. to 2:30 p.m. (there's a second tour on May 3), beginning at Mount Tam's Pantoll Ranger Station. Call 258-2410 to hear a taped message about upcoming hikes, or visit www.mttam.net. -- Heather Wisner

Anchors Away

SUN 4/27

Singer Christopher Cross said it best in "Sailing," his otherwise schlocky tribute to the sport: "And if the wind is right you can sail away/ And find tranquility." Local skippers may agree, though the waters are anything but tranquil during Opening Day on the Bay, the free maritime event that marks the opening of the 2003 boating season. The decorated-boat parade is the highlight of the annual festivities. Starting at noon, the Embarcadero from Crissy Field to Pier 39 will be a sea of red, white, and blue as hundreds of vessels set sail in honor of this year's patriotic theme: "The American Spirit: Stars and Stripes Forever." For more information, check out www.picya.org. -- Lisa Hom

Clean and Green

SAT 4/26

It's a double feature of good, clean fun: In the morning, volunteer to scrub, sweep, and generally spring-clean everything from Aquatic Park to Pier 39. Don't worry -- the Department of Public Works will be there to help, as will the San Francisco League of Urban Gardeners. In the afternoon, Earth Day for Life offers diverting presentations on worms, compost, organic rose cultivation, and recycled art. You can even bring unwanted computers and monitors for recycling. The Fisherman's Wharf Clean-Up begins at 9 a.m., and Earth Day for Life starts at noon. Both take place at Ghirardelli Square, 900 North Point (between Polk and Larkin). Call 563-1234. -- Hiya Swanhuyser

Weeds Are People, Too

SAT 4/26

Among the many wonders of the urban world are the courageous, the unstoppable, and the inspiring -- no, we're not talking about bicycle messengers. We're talking about wild plants, those life forms that crack pavement, cling to walls, and refuse to die even in the harshest of parking lots. (And you thought they were just weeds.) Artist/botanist Arcangelo Wessells and artist Michael Swaine lead the "Concrete Jungle Noticing Tour," a stroll through the sidewalk ecosystems around the Palace of Fine Arts. Reservations are required, but the tour, which starts at 1 p.m., is included in the price of admission to the Exploratorium (free-$10). To tag along, call 674-2870 by Friday, April 25. -- Hiya Swanhuyser