Lathyrus japonicus
Seaside pea
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Family: Fabaceae · Type: Vine · Native
Conservation status: CNPS 2B.1
Lathyrus japonicus (Seaside pea) is a native California vine in the Fabaceae family, recognized by coastal habitat with fleshy leaflets and large stipules diagnostic.
Seaside pea is a rare (CNPS 2B.1) California native perennial found in northern coastal areas of Del Norte and Humboldt counties along coastal beaches and dunes at elevations below 30 meters. Flowering from June to August, this plant produces blue-purple flowers with a two-colored appearance in compact clusters of 3 to 8 blooms. Growing with sprawling, angled stems that are glabrous or slightly hairy, it spreads across sandy coastal terrain with a delicate, climbing habit. Its leaves feature 6 to 8 fleshy, ovate or elliptic leaflets measuring 2.5 to 4.5 centimeters long, accompanied by distinctive branched or coiled tendrils. The plant's fruits are lightly covered in fine hairs, contributing to its subtle maritime charm.
Identification and appearance
Key characters: 15 sympatric species; coastal habitat with fleshy leaflets and large stipules diagnostic
Habitat and range
Habitat: Coastal beaches, dunes
Elevation: < 30 m
California counties: Del Norte, Humboldt, Siskiyou
Outside California: to Alaska, circumboreal, also Chile, Argentina
Bloom period
Lathyrus japonicus blooms Jun-Aug.
Conservation status
CNPS 2B.1
How to tell it apart
vs Vicia: Lathyrus style is flattened with hairs on top only; Vicia style is round and hairy all around.; vs Pickeringia: Lathyrus has tendrils and compound leaves; Pickeringia is a spiny shrub with simple leaves.; vs Pisum: Lathyrus has small normal stipules; Pisum has giant leafy stipules larger than leaflets.; vs Lupinus: Lathyrus has two leaflets and tendrils; Lupinus has palmate leaves with no tendrils.; vs Hosackia: Lathyrus has exactly two leaflets and tendrils; Hosackia has 3-9 leaflets with no tendrils.
Frequently asked questions
Is Lathyrus japonicus native to California?
Yes. Lathyrus japonicus is native to California (recorded as native).
When does Lathyrus japonicus bloom?
Lathyrus japonicus blooms Jun-Aug.
Where in California does Lathyrus japonicus grow?
Lathyrus japonicus occurs in Del Norte, Humboldt, Siskiyou, at elevations of < 30 m.
What plant family does Lathyrus japonicus belong to?
Lathyrus japonicus is in the Fabaceae family, genus Lathyrus.
Is Lathyrus japonicus rare or endangered?
Lathyrus japonicus carries California Rare Plant Rank 2B.1, state rank S2.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
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.