Geranium purpureum
Herb robert
(c) Douglas Goldman, some rights reserved (CC BY-SA) · licence
Family: Geraniaceae · Type: Annual · Not Native
Conservation status: Cal-IPC Yes
Geranium purpureum (Herb robert) is a non-native California annual in the Geraniaceae family, recognized by deeply dissected leaves and yellow anthers.
Herb robert is a naturalized annual found in northern coastal ranges, central coast, and San Francisco Bay Area in open to shaded sites at elevations below 100 meters. Flowering all year, this plant produces pink to red-purple flowers approximately 6 to 9 millimeters wide with yellow anthers. Growing with decumbent to ascending soft-haired stems 10 to 35 centimeters tall, it spreads with delicate branching habit. Its distinctive leaves are deeply divided into five segments, each pinnately lobed or dissected, with middle segments featuring up to 20 lobes in the upper half. The fruit develops as a small ribbed mericarp with long fibers at the tip, typical of the geranium family.
Identification and appearance
Key characters: 13 sympatric species; distinguished by deeply dissected leaves and yellow anthers
Habitat and range
Habitat: Open to shaded sites
Elevation: < 100 m
California counties: Butte, Alameda, Contra Costa, Sonoma, Marin, Santa Clara, Solano, Napa, San Mateo, Santa Cruz
Outside California: native to Europe, northern Africa, western Asia, alien in South America, New Zealand, southern Africa
Bloom period
Geranium purpureum blooms All year.
Conservation status
Cal-IPC Yes
How to tell it apart
vs Erodium: Geranium leaves are palmately divided like spread fingers; Erodium leaves are pinnately divided like a feather.; vs Pelargonium: Geranium is herbaceous with symmetrical flowers; Pelargonium is shrubby with asymmetrical flowers.; vs Sidalcea: Geranium has deeply palm-divided leaves; Sidalcea has shallowly palmately-lobed leaves and stamens fused in a column.; vs Bowlesia: Geranium has deeply divided leaves and pink flowers; Bowlesia has shallowly lobed leaves and tiny white umbel flowers.; vs Malva: Geranium has deeply palm-divided leaves with narrow segments; Malva has shallowly palmately-lobed leaves and fused stamens.
Frequently asked questions
Is Geranium purpureum native to California?
No. Geranium purpureum is not native to California (recorded as not native).
When does Geranium purpureum bloom?
Geranium purpureum blooms All year.
Where in California does Geranium purpureum grow?
Geranium purpureum occurs in Butte, Alameda, Contra Costa, Sonoma, Marin, Santa Clara, Solano, Napa and other counties, at elevations of < 100 m.
What plant family does Geranium purpureum belong to?
Geranium purpureum is in the Geraniaceae family, genus Geranium.
Is Geranium purpureum invasive in California?
Geranium purpureum is listed by Cal-IPC with an invasiveness rating of Yes.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-09-30
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.