The classification of the plant commonly knows as dune tansy (Tanacetum bipinnatum) is complex. Synonyms, often depending on location, are T douglasii, T huronense, T camphoratum and even Chrysanthemum bipinnatum. This native perennial is also known colloquially as Lake Huron tansy and camphor dune tansy, among other names. Some references, instead of using different species designations separate T bipinnatum into different subspecies. I am no expert, but to me all these synonyms seem to basically be Tanacetum bipinnatum, so I will simply use that scientific name.
Dune tansy is found from Northern California to Alaska and northeast across Canada to Newfoundland as well as in Asia and Europe. In the Pacific Northwest its habitat is coastal sand dunes.
Arising from extensive rhizomes, dune tansy is an aromatic plant that smells of camphor. The stout stems are moderately hairy. The basal leaves are intricately divided. The stem leaves are evergreen and gradually reduced in size upward.
The dune tansy inflorescence consists of few to several heads in a compact, semi-flat-toppped cluster. A member of the Aster Family (Asteraceae), the yellow dune tansy flower heads contain inconspicuous ray flowers and button-like disk flowers. The involucral bracts surrounding the flower head have light colored margins.
The fruits of dune tansy are achenes (dry seeds) weakly five-ribbed with a minute crown of tiny scales.
This rather uncommon wildflower can cause contact dermatitis.
The genus name comes from the Medieval Latin word “tanazita” which derives from the Greek “athanasia” meaning immortality. The reason behind the genus name is uncertain. The species designation means “having doubly pinnate leaves” and leaves no question as to its origin.
These dune tansy plants were photographed in May at Dry Lagoon Beach, Humboldt Lagoon State Park CA.