Centaurea jacea
Brown knapweed
(c) Jamie O'Neill, some rights reserved (CC BY) · licence
Family: Asteraceae · Type: Herb · Not Native
Centaurea jacea (Brown knapweed) is a non-native California herb in the Asteraceae family.
Brown knapweed is a naturalized perennial herb found in disturbed grasslands and open areas, typically growing in regions with agricultural or ruderal landscapes. Flowering from June to September, this plant produces distinctive purple flowers in hemispherical heads 15 to 18 millimeters wide with scarious phyllary appendages that range from light to dark brown or black. Growing with multiple branched stems 30 to 120 centimeters tall, the plant has a green coloration and is covered in short stiff or crinkly hairs. Its leaves vary from larger, entire to irregularly lobed basal leaves measuring 5 to 25 centimeters long to smaller, narrower entire upper leaves. The plant's unique phyllary appendages, which can be entire or dissected into fine wire-like lobes, create an intricate and textured appearance in the inflorescence.
Identification and appearance
Key characters: Geographically isolated from all other Centaurea species
How to tell it apart
vs Cirsium: Cirsium bracts taper to simple spines; Centaurea bract tips expanded with fringed/toothed edges; vs Carduus: Carduus bracts spine-tipped but not fringed; Centaurea bract appendages distinctly fringed or toothed; vs Jacobaea: Jacobaea has obvious yellow ray flowers; Centaurea lacks true rays (all tubular flowers); vs Silybum: Silybum has white-veined leaves and simple spine-tipped bracts; Centaurea bracts ornately fringed; vs Eriophorum: Eriophorum is a sedge with grass-like leaves and cottony heads; Centaurea is a branched herb
Frequently asked questions
Is Centaurea jacea native to California?
No. Centaurea jacea is not native to California (recorded as not native).
What plant family does Centaurea jacea belong to?
Centaurea jacea is in the Asteraceae family, genus Centaurea.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-08
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.