Its easy to tell if you’re looking at a gum plant. All the different species have big yellow daisy-like flowers perched atop a green nub that is studded with fleshy hooks. Before the young buds bloom they ooze a white sap that looks exactly like fresh Elmer’s glue.
San Francisco gum plant (Grindelia hirsutula var. maritima) only grows near the coast, on hills and bluffs from Marin to Monterey. I spotted these specimens on a recent hike to Chimney Rock on Point Reyes. Distinguish this plant from its cousin, coastal gumplant, because it grows on the hills instead of the salt marshes–but mainly because it doesn’t have perennial woody stems. San Francisco gum plant can vary dramatically in size, from 8 inches to nearly 5 feet. The plants I saw had hairy leaves, but according to the Marin Flora the leaves are usually hairless (aka “glabrous” in botany-speak).
Surprisingly, the Elmer’s glue doesn’t seem to have had any historical uses (that I’ve been able to unearth). But the dried leaves and buds were used to treat bronchial conditions including asthma.
Though there are three different species listed in the Marin Flora, it’s worth noting that some experts think that they all are actually part of the same species, Grindelia hirsutula.
Masses of yellow flowers are blooming beside the lagoon. Bees swarm over the blossoms, rummaging for pollen in their daisy-like centers. Nearby, white goo that looks like Elmer’s glue coats the younger, unopened buds. The green bracts surrounding the petals are fleshy spikes, curved strongly backward.
This is coastal gumweed, or Grindelia stricta. The species is highly variable, growing either upright to about waist height, or prostrate along the ground. You can find it along the Pacific coast from Los Angeles to Washington state. The erect version shown above (Grindelia stricta var. angustifolia) was photographed at the Bolinas Lagoon; it’s usually found in salt marshes. This is the only local species of Grindelia to have woody stems so it is easy to tell apart from other gumweeds. Other names for this species include Oregon gumweed and marsh gum plant.
Here is a common little tarweed with small unobtrusive flowers. Madia gracilis has the strong odor and sticky stem that’s common to the tarweeds (or gumweeds, which is another one of this little guy’s common names). The flowers are often dwarfed by the bulbous green cup of sepals below. If you look close you’ll see that the entire plant is covered with little glandular hairs, with tiny black dots atop stubby white bristles.