Ludwigia linifolia
Encycl., Suppl. 3: 513. 1814.
Herbs slender, rarely with aerenchyma, forming slender stolons 4–15 (–30) cm, 0.7–1 (–1.5) mm thick. Stems erect or ascending, slightly ridged, usually well branched, 12–55 (–62) cm, glabrous. Leaves alternate; stipules narrowly ovate to narrowly lanceolate, 0.2–0.3 × 0.1–0.2 mm; stolons: petiole narrowly attenuate, 0.05–0.5 cm, blade narrowly obovate or oblanceolate to spatulate, 0.5–2 × 0.1–0.6 cm; stems: sessile, blade linear to linear-oblanceolate, 1.5–4 × 0.1–0.4 (–0.6) cm, base very narrowly cuneate, margins entire with obscure hydathodal glands, apex acuminate to acute; bracts linear, reduced. Inflorescences leafy spikes, flowers solitary in leaf-axils; bracteoles attached 0–1.5 mm distal to base of ovary, very narrowly oblanceolate to linear, (1.5–) 2.5–9 (–13) × 0.2–0.8 mm, margins entire, apex acute. Flowers: sepals ascending, green, narrowly lanceolate-deltate, (3–) 4–7 × 1.1–1.7 mm, margins entire, apex narrowly acute, surfaces glabrous or minutely papillose; petals narrowly obovate-elliptic, 4–6 × 2–4 mm, base obtuse, apex obtuse or rounded; filaments pale-yellow, (1.3–) 1.5–2.5 (–3) mm, anthers oblong, 0.6–1.1 × 0.5–0.8 mm; pollen shed in tetrads; ovary subcylindric, 3–4 × 1–1.5 mm; nectary disc elevated 0.3–0.7 mm on ovary apex, bright-yellow, 0.8–1.5 mm diam., prominently 4-lobed, minutely papillose; style yellow, 1.25–2.5 mm, glabrous, stigma subcapitate, 0.3–0.6 × 0.6–0.8 mm, shallowly 4-lobed, not exserted beyond anthers. Capsules subcylindric, terete or slightly angled, 5–10 (–12) ×1.3–2 (–2.2) mm, hard-walled, irregularly dehiscent, pedicel 0 mm. Seeds reddish-brown, oblongelliptic, 0.6–0.7 × 0.2–0.3 mm, surface cells nearly isodiametric. 2n = 16.
Phenology: Flowering late Jun–Oct.
Habitat: Drainage ditches, margins of creeks or swamps, open edges of cypress swamps, moist pinelands, edges of brackish lakes.
Elevation: 0–300 m.
Distribution
Ala., Fla., Ga., Miss., N.C., S.C., Mexico (Tabasco)
Discussion
Ludwigia linifolia is primarily a coastal species that extends farther inland in Georgia and the Carolinas. Being one of five diploids in sect. Isnardia, it has particularly prominent nectary lobes and appears to be modally outcrossing (C. I. Peng 1989). It also is known from a disjunct population on the Yucatán Peninsula in Tabasco, Mexico.
Selected References
None.