Rumex crassus
Willow leaved dock
(c) Franco Folini, some rights reserved (CC BY) · licence
Family: Polygonaceae · Type: Perennial · Native
Rumex crassus (Willow leaved dock) is a native California perennial in the Polygonaceae family, recognized by . Coastal habitat and single large tubercle distinctive.
Willow leaved dock is a California native perennial found in the North Coast and Central Coast bioregions in coastal dunes, sandy shores, and marshes at elevations below 100 meters. Flowering from February to July, this plant produces small flowers in dense axillary and terminal clusters. Growing with decumbent to ascending stems 20 to 50 centimeters tall, it develops numerous axillary shoots below the primary flowering stems. Its thick, leathery leaves are lance-ovate to elliptic, 3 to 12 centimeters long with entire margins and acute tips. The fruit is small, 2 to 2.5 millimeters long, ranging from brown to dark red-brown with a distinctive large, warty tubercle.
Identification and appearance
Key characters: 12 sympatric species. Coastal habitat and single large tubercle distinctive.
Habitat and range
Habitat: Coastal dunes, sandy shores, marshes
Elevation: < 100 m
California counties: Del Norte, Santa Barbara, Humboldt, Marin, Mendocino, Monterey, San Francisco, San Luis Obispo, San Mateo, Santa Cruz, Sonoma, Ventura, Contra Costa
Outside California: Oregon
Bloom period
Rumex crassus blooms Feb-Jul.
How to tell it apart
vs Anemopsis: Rumex has dense flower clusters; Anemopsis has a single white cone-like flower head.; vs Amaranthus: Rumex has papery three-winged fruits; Amaranthus has small round seeds with papery covers.; vs Plantago: Rumex has branching flower clusters; Plantago has flowers in dense cylindrical spikes.; vs Eriogonum: Rumex has large broad leaves; Eriogonum typically has small basal leaf rosettes or mats.; vs Limonium: Rumex has green to reddish flower clusters; Limonium has papery purple or pink flowers.
Frequently asked questions
Is Rumex crassus native to California?
Yes. Rumex crassus is native to California (recorded as native).
When does Rumex crassus bloom?
Rumex crassus blooms Feb-Jul.
Where in California does Rumex crassus grow?
Rumex crassus occurs in Del Norte, Santa Barbara, Humboldt, Marin, Mendocino, Monterey, San Francisco, San Luis Obispo and other counties, at elevations of < 100 m.
What plant family does Rumex crassus belong to?
Rumex crassus is in the Polygonaceae family, genus Rumex.
What habitat does Rumex crassus grow in?
Rumex crassus grows in Coastal dunes, sandy shores, marshes.
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.