Despite its Latin epithet japonicus, this is a native ocean front species. Around coastal salt marshes, another native coastal pea L. palustris may be encountered. The two may be differentiated by the shape of leaf stipules. In beach pea, stipules are about as wide
as leaflets and more or less symmetrical, each with a pair of basal lateral lobes (three pairs of stipules can be found in
this photo). In marsh pea, stipules are narrower, asymmetrical, with a single sharply pointed basal lobe.