False loosestrife is an erect, branching perennial. Flowers have parts in fours (4 sepals, 4 stamens, etc.) and are usually borne singly, on very short peduncles from leaf axils. Base of flower swollen (a hypanthium); 4 bright yellow petals that often are shed the same day the flowers open. Blooms June–August. Leaves lanceolate, to 4 inches long, alternate, pointed, tapering at the base to hardly noticeable stems. Fruit a 4-sided capsule, ¼ inch long, that remains on the plant through the winter (hence the name “bushy seedbox”).
Similar species: There are 11 species of Ludwigia in Missouri. This one is distinguished by its nearly spherical or cubical fruits that open at a pore at the tip, by having definite flower stalks to about ¼ inch long (the flowers aren’t sessile), and by having as many stamens as sepals.
Height: to about 2½ feet; stem length approx. 2–4 feet.
Scattered nearly statewide, but apparently absent from most of the northwestern quarter.
Habitat and Conservation
Occurs on banks of streams, rivers, and spring branches, margins of ponds, lakes, and sinkhole ponds, marshes, fens, seeps, bottomland prairies, and swamps; also ditches, railroads, and roadsides.
False loosestrife does well cultivated as a water plant or in a rain garden, with its bright yellow flowers and showy fruits that enable it to self-seed.
Wetland plants can survive being flooded with water. Many animals eat wetland plants fresh, while others eat them as they decompose. Wetland plants help stabilize soils and absorb floodwater. This species apparently does not require cross-pollination in order to set seed.