Ludwigia decurrens - Walter
Onagraceae (Evening-Primrose) Family
Wingstem Water Primrose is a native annual herbaceous plant in the Evening-Primrose family (Onagraceae). It can be found throughout Alabama. The plant occurs on the shores of ponds and lakes, on the banks of rivers and streams, in marshes and swamps, and in wet roadside ditches. It is an annual with a tap root. Stems are green in color, 4-angled, winged, and branched from low on the stem. The stems often reach heights of 6 feet, and are very succulent. Wingstem is often abundant in disturbed wetlands.
The leaves are alternate, sessile, lanceolate in outline, with entire margins. The stems and leaves are glabrous or with a few very short hairs.
The flowers are stalked and produced singly in the axils of the leaves. The ovary is inferior. Each flower has 4 ovate, green sepals, and 4 bright yellow petals. Petals are easily detached from the flowers.
The fruit is an obconic capsule with many small, yellowish-brown seeds. The capsule is angled and winged on the angles.
Wingstem is introduced and considered a weed in California. The plant will grow in standing water. When it does, the lower portion of the stem often becomes enlarged and spongy, with white, spongy roots growing upwards out of the soil and into the water column.