marsh pea

Lathyrus linifolius is a perennial plant with a sprawling or climbing stem that grows to 25 to 80 cm (10 to 31 in) and is shallowly-winged and nearly hairless. The leaves are alternate with short winged stalks and long narrow stipules. The leaf blades are pinnate with two to four pairs of narrow lanceolate leaflets, entire margins and a terminal branching tendril. The inflorescence has a long stem and two to eight purple flowers, each 12 to 20 mm (0.5 to 0.8 in) long. These have five sepals and five petals and are irregular. The uppermost petal is known as the "standard", the lateral two as the "wings" and the lowest two are joined to form the "keel". There are ten stamens and a single carpel. The fruit is a flat brown pod containing up to twelve seeds. This plant flowers in July and August.

Lathyrus linifolius is native to Europe, parts of Asia and North America. Its typical habitat is in rich ground and this plant is found in damp meadows, on river banks, on the margins of ponds, by lakes and near the sea, and occasionally in coastal hedgerows. It often seems to grow among reeds (Phragmites australis). The species epithet palustris is Latin for "of the marsh" and indicates its common habitat. Marsh Pea grows from long rhizomes that allows the plant to spread vegetatively. As the common name implies, Marsh Pea, it is found in wet to moist areas where it can receive adequate sun and also allows other plants to climb on.