Field Trips

CNPS- Yerba Buena Natural History Walks:

Please note: Statewide CNPS is requiring signed waivers from event participants.

When noted, field trips require participants to sign online or paper waivers

And special thanks to our dedicated field trip leaders!

Upcoming Field Trips 2024


June 1, SATURDAY, 10 am to Noon

Lower Colma Canyon Dunes, San Bruno Mountain

Leader: Doug Allshouse

Imagine a 300-foot deep sand dune system that dates back 125,000-80,000 years ago, when the glaciers melted and San Bruno Mountain was almost an island—and it is almost 3 miles from the ocean! The dunes are a remnant of the Colma Formation that once stretched from Colma to the Presidio, but now is fragmented by post World War ll development in western San Francisco and Daly City. A piece of this site is relatively intact and supports a specific ecosystem not usually found at such a distance from the coast. Of great interest is the presence of the rare San Francisco lessingia (Lessingia germanorum) an endangered dune plant found only in the Presidio and the Dunes, its only known population in San Mateo County. Also present at the dunes is the rare San Francisco spineflower (Chorizanthe cuspidata), dune suncup (Camissonia strigulosa), contorted suncup (Camissonia contorta), miniature suncup (Camissoniopsis micrantha), California suncup (Camissoniopsis bistorta), and blue beach lupine (Lupinus chamissonis). A population of California pipevine (Aristolochia californica) is nearby, which means the sighting of beautiful Pipevine Swallowtails (Batus philenor) is a distinct possibility.

Wear sturdy shoes suitable for sand. This field trip will be restricted to 15 persons.

Contact Doug by email at, to reserve a spot and get directions to the meeting place.