Although it may be hard to imagine, much of San Francisco city and county was once covered in undulating sand dunes and thriving dune scrub habitat. Dune plants commonly have small, waxy, hairy, and/or succulent leaves, and deep root systems that allow them to survive in dry, nutrient-poor sand while being battered by wind and salt spray. Common native species include beach burr (Ambrosia chamissonis), yellow sand verbena (Abronia latifolia), dune strawberry (Fragaria chiloensis), sagewort (Artemisia pycnocephala), tansy (Tanacetum camphoratum), mock heather (Ericameria ericoides), chamisso bush lupine (Lupinus chamissonis), deerweed (Lotus scoparius), and cobweb thistle (Cirsium occidentale).
Unfortunately, many coastal dunes in the San Francisco Bay Area national parks have been overrun by European beachgrass (Ammophila arenaria) and iceplant (Carpobrotus edulis). These invaders were introduced in the late 1800s and early 1900s to control erosion and to stabilize the numerous sand dunes in the area. These species have since become so pervasive that they are outcompeting native dune plants and preventing the natural movement of sand that is an essential characteristic of this ever-changing habitat. The parks have undertaken a number of projects to try to remove these invasive species and restore native dune vegetation.