''Lathyrus japonicus'', the sea pea, beach pea, circumpolar pea or sea vetchling, is a species of flowering plant in the

legume A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock fo ...

family Fabaceae, native to temperate coastal areas of the Northern Hemisphere and Argentina. It is a

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition ...

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

growing trailing stems long, typically on sand and gravel storm beaches. The leaves are waxy glaucous green, long,

pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, an ...

, with 2-5 pairs of leaflets, the terminal leaflet usually replaced by a twining tendril. The flowers are broad, with a dark purple standard petal and paler purple wing and keel petals; they are produced in

raceme A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the sh ...

s of up to twelve flowers.

Description

''Lathyrus japonicus'' is a perennial plant. The stem grows to and is limp, has no wings and is often hairless. The leaves are alternate, greyish green and somewhat succulent, almost stalkless with large, wide

stipule In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). Stipules are considered part of the anatomy of the leaf of a typical flowering plant, although in many speci ...

s. The leaf blades are pinnate with three to five pairs of narrow lanceolate leaflets with blunt tips, entire margins and a terminal tendril. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed ...

has a long stem and five to twelve purple flowers, each long, turning bluer as they age. These have five sepals and five petals and are irregular with a standard, two wings and a fused keel. There are ten stamens and a single carpel. The fruit is a long brown pod up to in length. This plant flowers in mid-to-late summer (July and August in the Northern Hemisphere, January and February in the Southern Hemisphere).

Distribution and habitat

''Lathyrus japonicus'' is native to temperate parts of Europe, Asia, North and South America. Its typical habitat is sandy or stony seashores and other coastal locations. The unusually extensive native range is explained by the ability of the

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...

s to remain viable while floating in

sea water Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...

for up to five years, enabling the seeds to drift nearly worldwide. Germination occurs when the hard outer seed coat is abraded by waves on sand and gravel. The pods can be eaten but like many members of the genus ''

Lathyrus ''Lathyrus'' is a genus of flowering plants in the legume family Fabaceae, and contains approximately 160 species. Commonly known as peavines or vetchlings, they are native to temperate areas, with a breakdown of 52 species in Europe, 30 speci ...

'' they contain β-oxalyl-''L''-α,β-diaminopropionic acid, which can cause paralysis called

lathyrism Lathyrism is a condition caused by eating certain legumes of the genus ''Lathyrus''. There are three types of lathyrism: '' neurolathyrism'', '' osteolathyrism'', and '' angiolathyrism'', all of which are incurable, differing in their symptoms a ...

. The leaves of the plant are used in Chinese traditional medicine.

References

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japonicus This list of Latin and Greek words commonly used in systematic names is intended to help those unfamiliar with classical languages to understand and remember the scientific names of organisms. The binomial nomenclature used for animals and plants i ...

Edible legumes Flora of Asia Flora of Europe Flora of North America Flora of South America Flora of California Flora of Canada Flora of Greenland Flora without expected TNC conservation status {{fabeae-stub