Field Trips

CNPS- Yerba Buena Natural History Walks:

Woo-hooooo! Field trips are back! With county level health guidance restrictions, naturally.

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

Please complete the linked waiver for each field trip you will be attending. A paper version will be made available on site - signing is required to attend a field trip.

And special thanks to our dedicated field trip leaders!

Upcoming Field Trips 2023


June 3, SATURDAY, 10 am to Noonish

Colma Canyon Dunes, San Bruno Mountain

Leader: Doug Allshouse

Imagine a 300-foot deep sand dune system that dates back to the last inter-glacial period, 125,000-80,000 years ago, when San Bruno Mountain was almost an island, and it is 2 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 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). There may be a great bloom of farewell-to-spring (Clarkia rubicunda) on the backside. A population of California pipe vine (Aristolochia californica) is nearby, which means the sighting of beautiful Pipe Vine 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.