Zigzag Jointvetch

Annual, Herbs, Taproot present, Nodules present, Stems erect or ascending, Stems less than 1 m tall, Stems 1-2 m tall, Stems solid, Stems or young twigs sparsely to densely hairy, Stem hairs hispid to villous, Leaves alternate, Leaves petiolate, Stipules conspicuous, Stipules green, triangulate to lanceolate or foliaceous, Stipules persistent, Stipules free, Stipules connate to each other, forming a tuber or sheath, Stipules cordate, lobed, or sagittate, Leaves compound, Leaves even pinnate, Leaf or leaflet margins entire, Leaflets alternate or subopposite, Leaflets 10-many, Leaves viscid, st icky, Leaves glabrous or nearly so, Flowers in axillary clusters or few-floweredracemes, 2-6 flowers, Inflorescences racemes, Inflorescence axillary, Bracts very small, absent or caducous, Bracts hairy, Flowers zygomorphic, Calyx 5-lobed, Calyx 2-lipped or 2-lobed, Calyx hairy, Petals separate, Corolla papilionaceous, Petals clawed, Petals orange or yellow, Petals bicolored or with red, purple or yellow streaks or spots, Banner petal suborbicular, broadly rounded, Wing petals narrow, oblanceolate to oblong, Wing tips obtuse or rounded, Keel abruptly curved, or spirally coiled, Keel petals fused on sides or at tip, Stamens 9-10, Stamens monadelphous, united below, Filaments glabrous, Style terete, Fruit a loment, jointed, separating into articles, Fruit stipitate, Fruit unilocular, Fruit indehiscent, Fruit elongate, straight, Fruit rugose wrinkled or reticulate, Fruit exserted from calyx, Fruit compressed between seeds, Fruit hairy, Fruit 3-10 seeded, Seeds reniform, Seed sur face smooth, Seeds olive, brown, or black.

Aeschynomene rudis is a species of flowering plant in the legume family known by the common name zigzag jointvetch. It is native to South America but it is known from other continents, including North America, as a noxious weed, especially of wet areas such as rice fields. It is aquatic or semi-aquatic, growing bristly, glandular stems near or in water. It grows up to two metres tall. The leaves are composed of oval-shaped leaflets each about a centimetre long. At the base of each leaf are large, flat, pointed stipules. The flower is purple-tinted white and 1 to 1.5 centimetres wide. The fruit is a lobed, gland-dotted legume pod narrowed between the seeds. It is up to 5 centimetres long and less than one wide. As the pod dries it breaks into segments, each segment containing a seed. The hard, shiny seed is kidney-shaped and 2 or 3 millimetres long.