by Doreen Smith

The tarplant group, including the genus Calycadenia, has some late spring- to summer-flowering plants that may keep on blooming until fall.

Only two species of Calycadenia have been confirmed to occur in Marin. Calycadenia fremontii from Bootjack Camp is probably an erroneous record or a waif. The most abundant species we have is Calycadenia multiglandulosa (tack-stem), which has white flowers and is common in serpentine areas. The flowers of the inflorescence have unusual shapes; it’s often not recognized as being a member of the Asteraceae.

The other species, Calycadenia truncata (rosin weed), is common state-wide, but rare in Marin. It has yellow flowers and grows on igneous rocks on the topmost parts of Mt. Burdell.

Photos by Vernon Smith

Photo by Vernon Smith

Calycadenia multiglandulosa – (tack-stem)


Calycadenia truncata – (yellow rosinweed)