Ludwigia spathulata
Ludwigia brevipes
southern water purslane, spoon primrose-willow
Long Beach primrose-willow, ludwigiantha brevipes
prostrate or decumbent and ascending distally, slightly ridged, well branched, 10–40cm, densely strigillose throughout.
prostrate, ascending or erect at tips, terete, well branched, 20–70 cm, glabrous or, sometimes, minutely strigillose on leaf margins and inflorescence.
opposite;
stipules narrowly deltate or ovate, 0.05–0.15 × 0.05–0.1 mm;
petiole very narrowly winged, 0.3–0.9 cm, blade elliptic-spatulate or narrowly so, 0.9–1.7 × 0.3–0.9 cm, base attenuate, margins entire, apex acute, surfaces strigillose;
bracts not reduced except at branch tips.
opposite;
stipules narrowly deltate, 0.05–0.15 × 0.05–0.1 mm;
petiole narrowly winged, 0.2–0.8 cm, blades on submerged stems linear, 3.2–4.7 × 0.2–0.3 cm, those on emergent ones oblanceolate-elliptic to narrowly oblanceolate, (0.7–)1–1.7(–2) × 0.2–0.7(–1.1) cm, base very narrowly cuneate or attenuate, margins entire, apex acute;
bracts not reduced.
leafy spikes or racemes, flowers usually paired in leaf axils;
bracteoles attached at base of ovary or on short pedicel, narrowly oblong or oblanceolate, 0.2–0.8 × 0.05–0.2 mm, apex acute, often obscured by hairs.
sometimes few-flowered, erect racemes, flowers paired in leaf axils of prostrate stems;
bracteoles attached in opposite pairs at base of ovary or on pedicel distally, linear, 1–3(–4.5) × 0.1–0.7 mm, apex acuminate.
sepals ascending, pale green, broadly ovate-deltate, 1–1.7 × 1.1–1.7 mm, margins entire, apex acuminate, surfaces densely strigillose;
petals 0;
filaments translucent, 0.5–0.8 mm, anthers 0.2–0.4 × 0.3–0.5 mm;
pollen shed singly;
ovary oblong-obovoid, 4-angled to subterete, 1.5–2.5 × 1–1.5 mm;
nectary disc elevated 0.1–0.2 mm on ovary apex, yellowish green, 0.7–0.9 mm diam., 4-lobed, glabrous;
style yellowish green, 0.3–0.5 mm, glabrous, stigma pale yellow, capitate, 0.2–0.3 × 0.2–0.3 mm, not exserted beyond anthers.
sepals slightly reflexed at anthesis, ascending in fruit, light green, ovate-deltate or narrowly so, (3.5–)4–5(–6) × 1.7–3 mm, with 3 parallel veins, margins strigillose and finely serrulate, apex narrowly acute to elongate-acuminate, surfaces glabrous;
petals sometimes caducous, oblong-spatulate, 4.5–5.5 × 1.5–3 mm, base attenuate, apex obtuse;
filaments spreading, pale cream, 1.8–2.5 mm, anthers 0.7–1 × 0.5–0.7 mm;
pollen shed in very loose tetrads;
ovary obconic-cylindric, subterete or scarcely 4-angled, 3–5 × 2–2.5 mm;
nectary disc elevated 0.5–0.7 mm on ovary apex, bright yellow, 1.7–2.3 mm diam., 4-lobed, glabrate;
style cream, 1.1–1.7 mm, stigma cream, broadly capitate, 0.4–0.6 × 0.5–0.8 mm, often exserted beyond spreading stamens.
oblong-obovoid, subterete, 2.5–4(–4.5) × 1.5–2.5 mm, thin-walled, seeds often visible on exocarp as small bumps, irregularly dehiscent or dispersing as unit, pedicel 0–0.5 mm.
clavate, subterete to obscurely 4-angled, sometimes slightly curved, 6–10.5 × 2.5–4 mm, hard-walled, irregularly dehiscent, pedicel (4.5–)6–15(–20) mm.
dark reddish brown, ellipsoid, 0.5–0.7 × 0.4–0.5 mm, surface cells transversely elongate.
light to dark brown, ellipsoid, 0.6–0.7 × 0.3–0.5 mm, surface cells transversely elongate.
= 32.
= 48.
Ludwigia spathulata
Ludwigia brevipes
Flowers May–Sep. Ditches, swales, edges of ponds, lakes, sinks, swamps, sandy river bars, dried seasonal ponds, disturbed low savannas; of conservation concern; 0–200 m; Ala., Fla., Ga., S.C.
The tetraploid Ludwigia spathulata is relatively uncommon and occurs primarily on the Gulf Coastal Plain in the panhandle of Florida, southern Alabama, and southwestern Georgia. Outlying populations have also been collected in transitional areas between the Coastal Plain and the Piedmont in South Carolina and Georgia. With its small apetalous flowers, L. spathulata is modally autogamous and shows low morphological variability. Its strongest affinities appear to be with L. palustris, with which it shares a genome (C. I. Peng 1988, 1989).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The hexaploid Ludwigia brevipes is mainly restricted to the Atlantic coastal plain from central and eastern South Carolina to eastern North Carolina and extreme southeastern Virginia. The type collection of L. brevipes from middle New Jersey remains the only disjunct population north of the main range of this species more than 100 years after it was found. In 1988, an isolated population was found in the panhandle of Florida (Escambia County, Burkhalter 11065, MO) far to the southwest of the main range of L. brevipes; other reports of the species from Florida were erroneous (C. I. Peng 1989).
Ludwigia brevipes is known to hybridize with L. palustris producing the sterile L. ×lacustris Eames.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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