Ludwigia palustris |
Ludwigia decurrens |
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common water-primrose, eastern false loosestrife, ludwigie palustre, marsh primrose-willow, marsh purslane, marsh seedbox, water-purslane |
wingleaf primrose-willow |
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Habit | Herbs often creeping, rooting at nodes, forming mats. | Herbs annual or short-lived perennial, roots and lower stem sometimes inflated and spongy. |
Stems | prostrate or decumbent and ascending at tips, subterete or with raised lines decurrent from leaf axils, well branched, 10–50(–70) cm, glabrous or, sometimes, minutely strigillose on leaf margins and inflorescence. |
erect or strongly ascending, sharply 4-angled and 4-winged, 30–200 cm, simple to densely branched, glabrous. |
Leaves | opposite; stipules narrowly deltate, 0.05–0.1 × 0.05–0.1 mm; petiole narrowly winged, 0.1–2.5 cm, blade narrowly to broadly elliptic or ovate-elliptic, 0.5–4.5 × 0.3–2.3 cm, base abruptly attenuate, margins entire and minutely strigillose, apex subacute, surfaces glabrous; bracts not reduced. |
stipules deltate, 0.4–0.5 × 0.2 mm; sessile and continuous with wings on stem; blade lanceolate or narrowly lanceolate to narrowly ovate or elliptic, 2–20 × 0.2–5 cm, base acute or rounded, margins entire, often minutely scabrid, apex acute or acuminate, membranous, surfaces glabrous or sometimes minutely puberulent on abaxial veins; bracts linear, mostly reduced. |
Inflorescences | leafy spikes or racemes, flowers usually paired in leaf axils of prostrate stems; bracteoles attached at base or to 2.5 mm distal to base of ovary, sublinear, 0.3–1(–1.8) × 0.1–0.8 mm. |
open, leafy racemes, flowers solitary in distal axils; bracteoles deciduous, usually attached near base of ovary, without subtending glands, lanceolate to subovate, 0.5–1 × 0.2–0.5 mm, apex acute. |
Flowers | sepals ascending, green, ovate-deltate, 1.1–2 × 1–2.1 mm, margins finely serrulate with minute hairs, apex acuminate, sometimes with blunt tip, surfaces glabrous; petals 0; filaments translucent, 0.4–0.6 mm, anthers 0.2–0.4 × 0.3–0.6 mm; pollen shed singly; ovary oblong, 1.5–3.5 × 1–2 mm, glabrate; nectary disc elevated 0.15–0.3 mm on ovary apex, green, 1–2 mm diam., 4-lobed, glabrous; style pale green, 0.3–0.7 mm, glabrous, stigma subglobose or capitate, 0.4–0.6 × 0.2–0.4 mm, not exserted beyond anthers. |
sepals ovate to lanceolate, 7–12 × 1.5–4 mm, apex acute or short acuminate, membranous, margins usually minutely scabrid, surfaces usually glabrous, sometimes puberulent abaxially; petals orbiculate-obovate, 10–20 × 10–18 mm, short-clawed; stamens 8 in 2 subequal series, yellow, filaments 1.3–2.5 mm, anthers oblong, 1.3–1.6 × 0.5–0.6 mm; ovary obconic, sharply 4-angled and 4-winged, 6–10 × 2–4.5 mm, glabrous or minutely puberulent; nectary disc plane on ovary apex, 3–5 mm diam., 4-lobed, glabrate or ringed with short hairs; style 2.5–3.2 × 0.5–0.6 mm, stigma globose, 1–2 × 1–2 mm, not exserted beyond anthers and pollen shed directly on it. |
Capsules | oblong obovoid, 4-angled, (1.6–)2–5 × 1.5–3(–3.5) mm, thin-walled, irregularly dehiscent or dispersing as unit, pedicel 0–0.5 mm. |
rarely sharply curved, subclavate to oblong-obovoid or narrowly obpyramidal, sharply 4-angled and 4-winged, 10–25 × 3–5 mm, glabrous, pedicel 2–15 mm. |
Seeds | yellowish brown, ellipsoid, 0.5–0.7 × 0.3–0.4 mm, surface cells transversely elongate. |
oblong or subcylindric, 0.5–0.6 × 0.2 mm, striate, raphe very narrow and inconspicuous. |
2n | = 16. |
= 16. |
Ludwigia palustris |
Ludwigia decurrens |
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Phenology | Flowering Feb–Oct. | Flowering summer–early fall. |
Habitat | Roadside ditches, wet meadows, dried pond bottoms, margins of ponds, swamps, rivers, alluvial sand bars. | Moist or swampy habitats along sloughs, muddy stream banks, marshy shores of lakes and ponds, ditches, swamps. |
Elevation | 0–1000[–2700] m. (0–3300[–8900] ft.) | 0–300[–600] m. (0–1000[–2000] ft.) |
Distribution |
AL; AR; AZ; CA; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NE; NH; NJ; NM; NY; OH; OK; OR; PA; RI; SC; TN; TX; VA; VT; WA; WI; WV; BC; NB; NF; NS; ON; QC; Mexico (Chiapas, Chihuahua, Guerrero, Hidalgo, Jalisco, México, Michoacán, Morelos, Nuevo León, Oaxaca, San Luis Potosí, Sinaloa, Sonora, Tamaulipas, Veracruz); West Indies (Cuba, Hispaniola, Jamaica, Puerto Rico); Bermuda; Central America (Costa Rica, Guatemala, Panama); South America (Colombia, Peru, Venezuela); Europe; sw Asia; Africa; introduced in Pacific Islands (Hawaii, New Zealand); Australia
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AL; AR; DC; FL; GA; IL; KY; LA; MD; MO; MS; NC; OH; OK; PA; SC; TN; TX; VA; WI; WV; Central America; South America; Mexico (Campeche, Chiapas, Michoacán, Tabasco); West Indies; Bermuda [Introduced in Europe (France), e Asia (Japan), Africa (Cameroon), Pacific Islands (Philippines)]
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Discussion | Ludwigia palustris is a common diploid and most widely distributed species in sect. Isnardia. It is particularly widespread in temperate North America and in Europe [the type is thought to be from Europe (P. H. Raven 1963[1964]; C. I. Peng et al. 2005)], more sporadically in Africa and sw Asia, and introduced in Australasia, and Hawaii. The close sister relationship of sect. Isnardia with sect. Miquelia (L. ovalis Miquel only, endemic to eastern Asia) suggests that this clade may have had a history connected with the evolution of the Arcto-Tertiary Geoflora (P. H. Raven and D. I. Axelrod 1974; Peng et al.). Ludwigia palustris is known to hybridize with L. brevipes producing the sterile L. ×lacustris Eames. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Ludwigia decurrens appears to be most closely related to L. erecta, differing by having winged, not angled, capsules and larger flowers, with sepals 7–12 mm and petals 10–20 mm (in L. erecta, sepals 3–6 mm, petals 3.5–5 mm). They often grow in close proximity and may hybridize, but hybrids would be difficult to detect. Ludwigia decurrens is often self-pollinating, but larger flowers may promote outcrossing. Ludwigia jussiaeoides Michaux is an illegitimate later homonym of L. jussiaeoides Desrousseaux 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. Pterocaulon |
Sibling taxa | ||
Synonyms | Isnardia palustris, I. ascendens, I. nitida, I. palustris var. americana, L. apetala, L. nitida, L. palustris var. americana, L. palustris var. inundata, L. palustris var. liebmannii, L. palustris var. nana, L. palustris var. pacifica | Diplandra decurrens, D. montana, Jussiaea alata, J. bertonii, J. decurrens, J. palustris, J. pterophora, J. tenuifolia |
Name authority | (Linnaeus) Elliott: Sketch Bot. S. Carolina 1: 211. (1817) | Walter: Fl. Carol., 89. (1788) |
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