Cosmos sulphureus
Sulphur cosmos
(c) Annika Lindqvist, some rights reserved (CC BY), uploaded by Annika Lindqvist · licence
Family: Asteraceae · Type: Herb · Not Native
Cosmos sulphureus (Sulphur cosmos) is a non-native California herb in the Asteraceae family, recognized by ray color and leaf segment width provide clear distinction.
Sulphur cosmos is a naturalized annual found in southern California and potentially elsewhere in the California Floristic Province, occurring in disturbed places at elevations below 1,000 meters. Flowering from August to October, this plant produces vibrant yellow to red-orange flowers with ray petals 2 to 3 centimeters long in distinctive heads. Growing with stiffly hairy stems reaching 3 to 21 decimeters tall, it develops an open, branching structure. Its deeply divided leaves are petioled with intricate blades 5 to 12 centimeters long, segmented into narrow linear to lanceolate leaflets 2 to 5 millimeters wide. The flower heads feature an involucre 6 to 10 millimeters in diameter with distinctive linear outer phyllaries.
Identification and appearance
Key characters: 1 sympatric species; ray color and leaf segment width provide clear distinction
Habitat and range
Habitat: Uncommon escape from cultivation in disturbed places
Elevation: < 1000 m
Outside California: native to Mexico
Bloom period
Cosmos sulphureus blooms Aug-Oct.
How to tell it apart
vs Eriocapitella: Eriocapitella has simple lobed leaves, not the thread-like dissected foliage of Cosmos.; vs Tagetes: Tagetes has strongly aromatic foliage when crushed; Cosmos lacks strong scent.; vs Eupatorium: Eupatorium has simple opposite leaves and dense clusters of small fuzzy flowers, not large showy rays.; vs Zinnia: Zinnia has simple, undivided leaves; Cosmos has finely dissected thread-like leaf segments.; vs Dahlia: Dahlia has compound leaves with broad leaflets; Cosmos has thread-like dissected segments.
Frequently asked questions
Is Cosmos sulphureus native to California?
No. Cosmos sulphureus is not native to California (recorded as not native).
When does Cosmos sulphureus bloom?
Cosmos sulphureus blooms Aug-Oct.
What plant family does Cosmos sulphureus belong to?
Cosmos sulphureus is in the Asteraceae family, genus Cosmos.
What habitat does Cosmos sulphureus grow in?
Cosmos sulphureus grows in Uncommon escape from cultivation in disturbed places.
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.