Ludwigia grandiflora (Michx.) Greuter & Burdet

Showy Water Primrose; Large Flower Primrose Willow

Herb

Annual

Vascular

Showy Water Primrose is an introduced herbaceous perennial in the Evening-Primrose family (Onagraceae). It is native to Central and South America. It can be found at scattered locations throughout Alabama. Showy Water Primrose occurs in ponds, lakes, in roadside ditches, and in slow moving streams and rivers. It grows rooted at or near the shore and often forms large floating mats. The stems are green or reddish in color and pubescent with soft hairs. The stems are erect to decumbent and root at the nodes. Leaves are alternate, petiolate, spatulate to elliptic or lanceolate in outline, and pubescent. Flowers are solitary in the axils of the upper leaves. Each flower has 5-6 lanceolate green sepals and 5-6 obovate yellow petals. The ovary is inferior. The fruit is a capsule with the seed embedded in the endocarp. Showy Water Primrose is very similar to Creeping Water Primrose (Ludwigia peploides (Humboldt, Bonpland & Kunth) Raven ssp. glabrescens (Kuntze) Raven). That species has glabrous stems and leaves. It is also similar to Common Water Primrose (Ludwigia hexapetala (Hook. & Arn.) Zardini, H.Y. Gu & P.H. Raven) which is often treated as a variety of Showy Water Primrose. Showy Water Primrose grows vary rapidity and can choke out native vegetation. The large mats of floating stems make boating, fishing, and swimming difficult.--A. Diamond

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Not Native

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