Dandelions Anyone?

by Doreen Smith

One of the most difficult groups to identify to genus are the dandelions; by that I mean the yellow-flowered composites (Asteraceae), with heads of tubular flowers and milky juice if the stem is cut.

Most of the local native Marin dandelions are either in the genus Microseris or Agoseris. As examples, I will profile superficial look-alikes, the common Agoseris grandiflora and the rare Microseris paludosa. The latter species seems to have been extirpated from most of Marin and only remains on Point Reyes, found in seasonally moist grassland.

A helpful feature to distinguish between them is not something about the flowers, but the involucre, the green cluster of bracts immediately under the flower head. Microseris spp. have pointed bracts in the involucre, while Agoseris has rounded tips to the inner bracts. Their fruiting heads differ too; a Microseris fruit head is bristly; Agoseris spp. have puffy fruit heads. For more information about Marin’s several dandelion species, native and non-native, no serious student of Marin botany should be without a copy of Howell’s Marin Flora, no matter that the latest edition is from 2007!

Photos by Vernon Smith

Click on each thumbnail to see a larger image.