Helianthus petiolaris subsp. petiolaris
(c) Matt Berger, some rights reserved (CC BY), uploaded by Matt Berger · licence
Family: Asteraceae · Type: Herb · Not Native
Helianthus petiolaris subsp. petiolaris is a non-native California herb in the Asteraceae family, recognized by wider phyllaries and annual habit.
Naturalizing sunflower is a non-native annual found in the San Francisco Bay Area and southwestern California in disturbed areas at elevations generally below 450 meters. Flowering from May to October, this plant produces yellow flowers with dark centers in heads approximately 5 to 8 centimeters wide. Growing with branching stems 30 to 100 centimeters tall, it has rough, short-hairy stems that spread across open ground. Its leaves are strigose (covered in straight, appressed hairs), with rough green surfaces that appear somewhat bristly to the touch. The plant's distinctive disk flowers have a corolla throat that abruptly narrows to a densely hairy basal region, creating a unique textural appearance.
Identification and appearance
Key characters: 7 sympatric species; distinguished by wider phyllaries and annual habit
Habitat and range
Habitat: Disturbed areas
Elevation: generally < 450 m
Outside California: native to west-central United States
Bloom period
Helianthus petiolaris subsp. petiolaris blooms May-Oct.
How to tell it apart
vs Encelia: Helianthus is herbaceous with soft stems; Encelia is a woody shrub with persistent branches.; vs Bahiopsis: Helianthus has soft herbaceous stems; Bahiopsis is woody-based with persistent woody stems.; vs Wyethia: Helianthus has smaller disk flowers and readily falling seed scales; Wyethia has very large 8-12mm disk flowers.; vs Rudbeckia: Helianthus has a flat or rounded yellow center; Rudbeckia has a tall dark cone-shaped center.; vs Venegasia: Helianthus dies back to ground level; Venegasia is a large evergreen shrub in shaded canyons.
Frequently asked questions
Is Helianthus petiolaris subsp. petiolaris native to California?
No. Helianthus petiolaris subsp. petiolaris is not native to California (recorded as not native).
When does Helianthus petiolaris subsp. petiolaris bloom?
Helianthus petiolaris subsp. petiolaris blooms May-Oct.
What plant family does Helianthus petiolaris subsp. petiolaris belong to?
Helianthus petiolaris subsp. petiolaris is in the Asteraceae family, genus Helianthus.
What habitat does Helianthus petiolaris subsp. petiolaris grow in?
Helianthus petiolaris subsp. petiolaris grows in Disturbed areas.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.