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southern water purslane, spoon primrose-willow

creeping primrose-willow, creeping water primrose, creeping waterpurslane, red ludwigia

Habit Herbs creeping and rooting at nodes, often forming mats. Herbs creeping and rooting at nodes, often forming loose mats.
Stems

prostrate or decumbent and ascending distally, slightly ridged, well branched, 10–40cm, densely strigillose throughout.

prostrate, ascending to suberect at tips, terete, sparsely branched, 30–80 cm, glabrous or, sometimes, minutely strigillose on leaf margins and inflorescence.

Leaves

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, 0.05–0.1 × 0.05–0.1 mm;

petiole narrowly winged, 0.3–2.3 cm, blade narrowly elliptic to broadly lanceolate-elliptic or suborbiculate, 0.8–4.5 × 0.4–2.7 cm, base attenuate, margins entire or sometimes with hydathodal glands, apex acute or apiculate, rarely obtuse, surfaces lustrous, subglabrous or sparingly to densely papillose strigillose;

bracts not much reduced.

Inflorescences

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 to pedicel 1–5 mm proximal to base of ovary, lanceolate to narrowly oblong-lanceolate or sublinear, 1–5(–8) × 0.2–1 mm, apex acute, surfaces sparingly minutely strigillose.

Flowers

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 ascending, light green, ovate deltate to narrowly so, 1.8–5 × 1.5–3.5 mm, margins minutely strigillose, apex acuminate to elongate-acuminate, surfaces subglabrous;

petals caducous, oblanceolate to elliptic-oblong, 1.1–3 × 0.4–1.4 mm, base attenuate, apex obtuse, often variable in size and shape in same flower;

filaments pale yellow, 0.5–1.5 mm, slightly inflated near base, anthers 0.4–0.9 × 0.3–0.8 mm;

pollen shed singly or in tetrads;

ovary obconic-cylindric, barely 4-angled to subterete, 2–6 × 2.5–3.5 mm;

nectary disc elevated 0.3–0.8 mm on ovary apex, yellow, 1.1–3 mm diam., 4-lobed, glabrous;

style pale yellow, 0.6–0.9 mm, glabrous, stigma pale yellow, broadly capitate, 0.3–0.5 × 0.3–0.8 mm, usually not exserted beyond anthers.

Capsules

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.

elongate-obpyramidal, 4-angled, corners sometimes rounded, 4–10 × 2.5–4 mm, hard-walled, irregularly dehiscent, pedicel 0.1–3 mm.

Seeds

dark reddish brown, ellipsoid, 0.5–0.7 × 0.4–0.5 mm, surface cells transversely elongate.

yellowish brown, ellipsoid, 0.6–0.8 × 0.3–0.5 mm, surface cells transversely elongate.

2n

= 32.

= 48.

Ludwigia spathulata

Ludwigia repens

Distribution
from USDA
[BONAP county map]
from USDA
[WildflowerSearch map]
[BONAP county map]
Discussion

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.)

Flowers Mar–Nov (year-round). Muddy or damp, sandy edges of pools, lakes, swamps, creeks, and roadside ditches, moist soil in solution pits in limerock and hammock clearings in Florida Everglades, shade or sun; 0–1200[–1600] m; Ala., Ariz., Calif., Fla., Ga., Kans., La., Miss., Nev., N.J., N.Mex., N.C., Okla., Oreg., S.C., Tenn., Tex., Va.; Mexico (Chihuahua, Coahuila, México, Morelos, Nuevo León, Puebla, San Luis Potosí, Sonora); West Indies (Bahamas, Cuba, Hispaniola, Jamaica); Bermuda; introduced in Asia (Bangladesh, Japan).

Ludwigia repens occurs primarily on the Atlantic and Gulf coastal plains of the United States from North Carolina to Texas, with more scattered distribution into west Texas, New Mexico, Oklahoma, and Kansas, and disjunct populations in New Jersey, Tennessee, southern Arizona, Nevada, California, and western Oregon (Marion County); it also occurs in northern and central Mexico and the Caribbean region. In some parts of this wide range it is considered an aquatic weed.

Ludwigia repens is one of the most popular species of Ludwigia used in the aquarium trade; this may help to account for its wide distribution.

Much like the related diploid Ludwigia palustris, the hexaploid L. repens is widespread and morphologically variable, and infraspecific taxa have been proposed to describe this variation. Given the tendency of species in sect. Isnardia to hybridize, and the lack of a geographical basis for much of the variation, C. I. Peng (1989) declined to adopt any infraspecific classification, and this treatment follows Peng.

As described in C. I. Peng et al. (2005), Ludwigia repens J. R. Forster was conserved with a new type (the original type selected was from Virginia, where the species does not occur); L. repens Swartz (1797) was a later homonym described from Jamaica and pertains here.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Isnardia Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Isnardia
Sibling taxa
L. alata, L. alternifolia, L. arcuata, L. bonariensis, L. brevipes, L. curtissii, L. decurrens, L. erecta, L. glandulosa, L. grandiflora, L. hexapetala, L. hirtella, L. lanceolata, L. leptocarpa, L. linearis, L. linifolia, L. maritima, L. microcarpa, L. octovalvis, L. palustris, L. peploides, L. peruviana, L. pilosa, L. polycarpa, L. ravenii, L. repens, L. simpsonii, L. sphaerocarpa, L. suffruticosa, L. virgata
L. alata, L. alternifolia, L. arcuata, L. bonariensis, L. brevipes, L. curtissii, L. decurrens, L. erecta, L. glandulosa, L. grandiflora, L. hexapetala, L. hirtella, L. lanceolata, L. leptocarpa, L. linearis, L. linifolia, L. maritima, L. microcarpa, L. octovalvis, L. palustris, L. peploides, L. peruviana, L. pilosa, L. polycarpa, L. ravenii, L. simpsonii, L. spathulata, L. sphaerocarpa, L. suffruticosa, L. virgata
Synonyms Isnardia spathulata Isnardia intermedia, I. natans, I. repens, I. repens var. rotundata, L. fluitans, L. natans, L. natans var. rotundata, L. natans var. stipitata, L. repens var. rotundata, L. repens var. stipitata
Name authority Torrey & A. Gray: Fl. N. Amer. 1: 526. (1840) J. R. Forster: Fl. Amer. Sept., 6. (1771) — (as Ludvigia), name conserved
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