Centaurea melitensis
Tocalote; maltese star-thistle, Tocalote
Photo by Chez Brungraber
Family: Asteraceae · Type: Herb · Not Native
Conservation status: Cal-IPC Yes
Centaurea melitensis (Tocalote; maltese star-thistle) is a non-native California herb in the Asteraceae family, recognized by yellow flowers, winged stems, and shorter spines (5-10mm) distinguish from C. solstitialis.
Tocalote is a naturalized annual found in California's Central Valley, Foothills, and Desert regions in disturbed fields and open woodlands at elevations below 2,200 meters. Flowering from April to July, this plant produces yellow flowers in heads with distinctive purple-tipped, spine-fringed phyllaries. Growing 1 to 10 decimeters tall with a single stem that becomes branched and winged, it has a gray-hairy appearance with resin-dotted foliage. Its lower leaves range from entire to lobed and can be up to 15 centimeters long, while upper leaves are entire or toothed and long-decurrent along the stem. The plant's seed heads feature spiny, straw-colored involucres with central spines 5 to 10 millimeters long, creating a distinctive star-thistle appearance.
Identification and appearance
Key characters: 15 sympatric species; yellow flowers, winged stems, and shorter spines (5-10mm) distinguish from C. solstitialis
Habitat and range
Habitat: Disturbed fields, open woodland
Elevation: < 2200 m
Outside California: native to southern Europe
Bloom period
Centaurea melitensis blooms Apr-Jul.
Conservation status
Cal-IPC Yes
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 melitensis native to California?
No. Centaurea melitensis is not native to California (recorded as not native).
When does Centaurea melitensis bloom?
Centaurea melitensis blooms Apr-Jul.
What plant family does Centaurea melitensis belong to?
Centaurea melitensis is in the Asteraceae family, genus Centaurea.
Is Centaurea melitensis invasive in California?
Centaurea melitensis is listed by Cal-IPC with an invasiveness rating of Yes.
What habitat does Centaurea melitensis grow in?
Centaurea melitensis grows in Disturbed fields, open woodland.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.