Ludwigia simpsonii |
Ludwigia decurrens |
|
---|---|---|
Simpson's primrose-willow |
wingleaf primrose-willow |
|
Habit | Herbs sometimes creeping and rooting at nodes, new shoots arising from trailing stems or main caudex, rarely forming stolons. | Herbs annual or short-lived perennial, roots and lower stem sometimes inflated and spongy. |
Stems | erect, ascending, decumbent, or prostrate, slightly ridged, well branched, 10–60(–75) cm, glabrous, with raised lines decurrent from leaf axils. |
erect or strongly ascending, sharply 4-angled and 4-winged, 30–200 cm, simple to densely branched, glabrous. |
Leaves | alternate or proximal pairs opposite; stipules narrowly ovate-deltate, 0.1–0.3 × 0.1–0.2 mm, succulent; petiole winged, 0.2–1 cm, blade spatulate or oblanceolate to very narrowly oblanceolate or sublinear, 0.6–1.5(–2) × (0.1–)0.3–0.7(–1.1) cm, base attenuate, margins subentire with hydathodal glands, apex acute or mucronate; bracts not much 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 | open, leafy spikes or racemes, flowers solitary in leaf axils; bracteoles attached in opposite pairs near base of ovary, lanceolate-elliptic, 0.9–1.5(–2.5) × 0.4–0.9 mm, swollen at base, apex acuminate. |
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, creamy white near base adaxially, ovate-deltate, 1.2–1.8 × 1–2 mm, margins entire, apex narrowly acute or acuminate, surfaces glabrous; petals 0 or very rare; filaments nearly translucent, 0.5–0.8 mm, anthers 0.2–0.4 × 0.3–0.4 mm; pollen shed singly; ovary obconic, subterete or scarcely 4-angled, 1.2–1.8 × 1.2–2 mm; nectary disc elevated 0.3–0.4 mm on ovary apex, green, 0.9–1.3 mm diam., distinctly 4-lobed, glabrous; style pale green, 0.4–0.6 mm, stigma pale yellow, subglobose, 0.2–0.3 × 0.2–0.3 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 | obconic, obscurely 4-angled, 1.5–2.5 × 1.5–3 mm, hard-walled, dehiscent by loculicidal slits, pedicel 0–0.4 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 | light brown or brown, ellipsoid, 0.5–0.6 × 0.3–0.4 mm, surface cells transversely elongate, glabrous, occasionally covered by minute waxy hairs. |
oblong or subcylindric, 0.5–0.6 × 0.2 mm, striate, raphe very narrow and inconspicuous. |
2n | = 48. |
= 16. |
Ludwigia simpsonii |
Ludwigia decurrens |
|
Phenology | Flowering Apr–Nov (year-round). | Flowering summer–early fall. |
Habitat | Sandy, peaty ditches, open pineland swamps, edges of cypress swamps, tidal flats and nearby marshes, limestone sinks. | Moist or swampy habitats along sloughs, muddy stream banks, marshy shores of lakes and ponds, ditches, swamps. |
Elevation | 0–50 m. (0–200 ft.) | 0–300[–600] m. (0–1000[–2000] ft.) |
Distribution |
FL; MS; West Indies (Cuba, Jamaica) |
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)]
|
Discussion | Ludwigia simpsonii is a hexaploid species occurring primarily in Florida, with outlier populations in southern Mississippi, western Cuba, and Jamaica. The species grows frequently in close proximity to L. curtissii; it grows mainly along roadside ditches with other weeds, whereas L. curtissii grows in less disturbed habitats, and the two seldom occur side by side (C. I. Peng 1989). Peng (1988, 1989) suggested that the hexaploid (2n = 48) L. simpsonii and the diploid (2n = 16) L. microcarpa gave rise to L. curtissii, the only octoploid (2n = 64) in sect. Isnardia. (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 | ||
Sibling taxa | ||
Synonyms | L. cubensis, L. curtissii var. simpsonii | Diplandra decurrens, D. montana, Jussiaea alata, J. bertonii, J. decurrens, J. palustris, J. pterophora, J. tenuifolia |
Name authority | Chapman: Fl. South. U.S. ed. 2 repr. 2, 685. (1892) — (as simpsoni) | Walter: Fl. Carol., 89. (1788) |
Web links |