Sunflowers are members of the Helianthus genus of the Aster family (Asteraceae).
Native to Woodland
This planter box in a garden in Woodland contains two California Sunflower (Helianthus californicus) plants in different stages of growth: one blooming, and the other still preparing to bloom. Photo by queerbychoice.
Most often, the term "sunflower" refers to the Common Sunflower (Helianthus annuus). Common Sunflowers are native to Woodland and are also grown locally for commercial seed production. They can be found both in farm fields and in personal gardens. Sunflower seeds are one of Yolo County's highest-grossing agricultural commodities. They are annual herbs that can grow as much as ten feet tall but typically stay only two to three feet wide. Their flower heads can be up to 8 inches in diameter. They like full sun and usually grow in dry, unwatered places.
In addition to Common Sunflowers, one other sunflower species is also native to Woodland.
Serpentine Sunflower (Helianthus bolanderi) is an annual or perennial herb native to all of Woodland. It grows three to five feet tall and about equally wide, with many stems branched from ground level. It prefers full sun and can grow equally well in wetlands or in drylands, adapting its size to suit the amount of water available.
Native to Yolo County
In addition to the two species above, a third sunflower species is native elsewhere in Yolo County.
California Sunflower (Helianthus californicus) is a perennial herb native to the southern two thirds of West Sacramento, the far southeastern edges of Davis, and the Yolo County foothills. It can grow as much as eleven feet tall and nearly four feet wide. It prefers full sun and grows exclusively in wetlands.
In the foreground, a single Serpentine Sunflower (Helianthus bolanderi) plant in a garden in Woodland. In the background, the smaller yellow flowers are native Woolly Sunflowers (Eriophyllum lanatum 'Siskiyou'), but these are not true sunflowers, since they are in a different genus. Photo by queerbychoice.
A California Sunflower (Helianthus californicus) towers over a garden in Woodland. Photo by queerbychoice.
Sunflowers in general (in the genus Helianthus) are ranked 5 out of 10 on the Ogren Plant Allergy Scale, indicating a mild to moderate tendency to cause hay fever. Sunflowers are in the Heliantheae tribe of the Aster Family, which also contains Ragweed, so cross-reactions are common. People who are allergic to sunflowers may also be allergic to varying degrees to aster family plants in general.
Other Plants Often Called "Sunflowers"
Some other yellow flowers in the Aster family are commonly called "sunflowers" but are not true sunflowers. The most notable of these is probably the Woolly Sunflower (Eriophyllum lanatum), which is native to all of Woodland and can grow about three feet tall and wide in dry soil and full sun or partial shade. A cultivar called 'Siskiyou' is commonly sold that stays shorter. Although Woolly Sunflowers are in the same plant family as true sunflowers, they are not otherwise particularly closely related, being not only in different genera but also in different tribes of the Asteroideae subfamily.
Links
CalScape: Helianthus bolanderi
Wikipedia: Helianthus bolanderi
CalScape: Helianthus californicus
Wikipedia: Helianthus californicus
