On an open hillside is a graceful thistle with whitish stems and leaves. Look close and you’ll see a cobweb-like webbing stretched between the spines. This is cobweb thistle (Cirsium occidentale), one of the most beautiful of the native thistles. A busy community of bees, ants and other insects also find it attractive! You’ll see them buzzing and crawling around the plant and (apparently) sometimes dozing in the flowers.
There are a LOT of thistles in the area; CalFlora lists eighteen different species, most of which are invasive. But unlike these non-native species, cobweb thistle tends to grow singly or in sparse groups. And plus, it’s cobwebby. There are other native species with this feature (the technical term for cobwebby is “arachnoid”) but they have leaves right beneath the flower head, and a very different growth form.
Flowers Of Marin 