Bloomipedia
Seaside pea (Lathyrus japonicus)
Photo: Michael via iNaturalist · CC BY 4.0 · resized

Flower profile

Seaside pea

Lathyrus japonicus

Native in the lower 48

Seaside pea is a wildflower that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 3 states, and across the U.S. it's most often seen in bloom in May–September.

19states
3of our state lists
9,934U.S. sightings*

*iNaturalist research-grade observations, as of October 17, 2026.

On our lists for: Maine, Massachusetts, Rhode Island

Quick look

Lathyrus japonicus, the sea pea, beach pea, circumpolar pea or sea vetchling, is a species of flowering plant in the legume family Fabaceae, native to temperate coastal areas of the Northern Hemisphere.

  • It belongs to the Fabaceae family. iNaturalist
  • USDA PLANTS describes it as an herb (forb) / a vine with a perennial life cycle. USDA PLANTS
  • USDA PLANTS lists it as native in the lower 48 states and records it in 19 states. USDA PLANTS
  • NatureServe lists it as native to Massachusetts, Maine and Rhode Island. NatureServe
  • In Massachusetts, most iNaturalist sightings of it in flower come in May–September. iNaturalist
  • In Maine, most iNaturalist sightings of it in flower come in May–September. iNaturalist
  • USDA PLANTS lists its flower color as purple. USDA PLANTS
  • USDA PLANTS gives its bloom period as early spring. USDA PLANTS
  • USDA PLANTS lists a mature height of about 1.5 ft. USDA PLANTS
  • iNaturalist has 1,491 research-grade sightings of it in Massachusetts, ranking #98 among the 110 flowers on our Massachusetts list. iNaturalist
  • iNaturalist has 1,465 research-grade sightings of it in Maine, ranking #39 among the 110 flowers on our Maine list. iNaturalist
  • iNaturalist has 299 research-grade sightings of it in Rhode Island, ranking #50 among the 110 flowers on our Rhode Island list. iNaturalist

Seaside pea gift ideas

Handmade seaside pea gifts from independent makers.

🌱 Sample spot. Handmade gift picks from independent shops will appear here once our shop partnership is approved. These cards are placeholders, not real products.

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    Seaside pea art print

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When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (901 records)
Bloom time in each of our 3 states
StateTypePeak bloomSightings*
MassachusettsNativeMay–September1,491
MaineNativeMay–September1,465
Rhode IslandNativefew records299

Conservation status

Federal (U.S. ESA)
Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. USFWS ECOS
NatureServe global
G5 Secure worldwide. NatureServe
Massachusetts
Not listed Not on Massachusetts Endangered Species Act list (321 CMR 10.90). NatureServe: SNR, not yet ranked in Massachusetts. MESA list
Maine
Not listed Not on Maine Rare Plant List (Maine Natural Areas Program, 2021). E and T are Maine's official endangered and threatened plants (12 M.R.S.); SC and PE are tracking categories. NatureServe: SNR, not yet ranked in Maine. Maine rare plant list
Rhode Island
Not listed Not on Rhode Island Rare Plants 2016 (RI Natural History Survey, from the RI Wildlife Action Plan; informational, Rhode Island has no state plant-protection listing law). NatureServe: SNR, not yet ranked in Rhode Island. RI rare plants 2016
Rare elsewhere
Other states where NatureServe ranks it rare or missing: CA (S2), IN (S1), OH (S2), PA (S2), VT (S2). (S1 critically imperiled, S2 imperiled, SH possibly extirpated, SX presumed extirpated.)

Checked October 17, 2026. Rankings and lists can change, so follow the links for the latest.

Can you eat it?

For peopleNot well documented

None of the sources we checked (NC State Extension (no page for this plant), USDA PLANTS) say whether it's edible or poisonous for people.

For petsNot well documented

It isn't on the ASPCA plant list. For context only: ASPCA lists a related species, Lathyrus latifolius (“Sweet Pea”), as non-toxic to dogs and cats. That doesn't tell us about this species, so keep pets away to be safe. ASPCA

🌿 Never eat a wild plant unless you're certain of its ID; this isn't medical advice. Worried about a person? Call Poison Control at 1-800-222-1222. Worried about a pet? Call your vet.

Where does it grow?

USDA PLANTS records seaside pea in 19 states.

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Alaska, California, Connecticut, Illinois, Indiana, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Ohio, Oregon, Pennsylvania, Rhode Island, Vermont, Washington, Wisconsin.

Massachusetts counties with USDA records: Barnstable, Bristol, Dukes, Essex, Nantucket, Norfolk, Plymouth, Suffolk.

Maine counties with USDA records: Cumberland, Hancock, Knox, Lincoln, Sagadahoc, Waldo, Washington, York.

Rhode Island counties with USDA records: Bristol, Newport, Providence, Washington.

More Massachusetts flowers

White clover (Trifolium repens)

White clover

Trifolium repens

Introduced

🌼 Blooms in MA: May–September
Red clover (Trifolium pratense)

Red clover

Trifolium pratense

★ VT state flowerIntroduced

🌼 Blooms in MA: May–October
Purple crownvetch (Securigera varia)

Purple crownvetch

Securigera varia

★ PA state beautification and conservation plantIntroduced

🌼 Blooms in MA: June–September

Sources