Ludwigia erecta

Herbs annual, rarely persistent a second year from woody base. Stems erect, 4-angled, rarely 4-winged, sometimes basally terete, 40–280 cm, simple to densely branched, branches often ascending, glabrous. Leaves: stipules deltate, 0.2–0.3 × 0.15–0.2 mm; petiole 0.2–2.2 cm, somewhat flattened and continuous with ridges or wings on stem; blade elliptic to narrowly lanceolate, 2–20 × 0.2–4 cm, base cuneate, margins minutely scabrid, apex acute or acuminate, membranous, sur­faces glabrous or sometimes minutely strigillose along ab­axial veins; bracts often reduced. Inflorescences leafy spikes, flowers solitary in distal axils; bracteoles attached at base of ovary or on lower 1/2, without subtending glands, deltate, 0.3–0.5 × 0.2–0.3 mm, apex acute. Flowers: sepals ovate or lanceolate, 3–6 × 1–2 mm, apex acute or short-acuminate, surfaces usually glabrous, sometimes strigillose; petals obovate, 3.5–5 × 2–2.5 mm; stamens 8 in 2 subequal series, filaments 1.3–1.5 mm, anthers oblong, 0.6–1 × 0.4–0.5 mm; ovary obconic, 4-angled, 4–10 × 2–4 mm, usually glabrous, rarely strigillose; nectary disc plane on ovary apex, 3–4 mm diam., 4-lobed, glabrate; style 0.5–1.5 × 0.5–0.6 mm, stigma globose, 0.8–1 × 1–1.2 mm, not exserted beyond anthers and pollen shed directly on it. Capsules oblong-linear to squarish-cylindric, 4-angled, 10–22 × 2–4 mm, thin-walled, irregularly dehiscent, subsessile. Seeds elongate-ovoid, 0.3–0.5 × 0.2–0.3 mm, raphevery reduced and inconspicuous. 2n = 16.

Phenology: Flowering summer–early fall.
Habitat: Pond margins and depressions, wet sand ditches and prairies.
Elevation: 0–100[–300] m.

Distribution

• Generated Map
• Legacy Map

Ala., Ariz., Fla., Mexico (Campeche, Chiapas, Jalisco, Michoacán, Nayarit, Oaxaca, Tabasco), West Indies, Central America, South America, Africa (Nigeria, Tanzania), Indian Ocean Islands (Comoros Islands, Madagascar, Seychelles).

Discussion

Ludwigia erecta, which is morphologically similar to L. decurrens and often growing with it, is modally self-pollinating and is usually easy to distinguish from that species.

Although Ludwigia erecta is widely distributed in warm temperate regions in the New World and Africa, it appears to be most closely related to species restricted to South America. Its appearance in a rather remote locality in Arizona in 2006 may be attributable to transport there in mud on migrating birds.

Selected References

None.

Lower Taxa

None.