Ludwigia simpsonii |
Ludwigia alata |
|
---|---|---|
Simpson's primrose-willow |
wing primrose-willow |
|
Habit | Herbs sometimes creeping and rooting at nodes, new shoots arising from trailing stems or main caudex, rarely forming stolons. | Herbs with aerenchyma when base submerged, forming stolons from lower nodes, 8–65(–95) cm, 0.7–2.5 mm thick. |
Stems | erect, ascending, decumbent, or prostrate, slightly ridged, well branched, 10–60(–75) cm, glabrous, with raised lines decurrent from leaf axils. |
erect or somewhat sprawling, slightly to distinctly winged (wings to 1.8 mm wide), branched distally, 40–120(–160) cm, 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. |
alternate; stipules ovate-deltate, often narrowly so, 0.2–0.4 × 0.1–0.3 mm, succulent; stolons: petiole 0.15–1 cm, blades orbiculate to oblanceolate or broadly elliptic, 0.4–2.6 × 0.4–1.5 cm, base attenuate, apex rounded to subacute; stems: petiole 0–0.3 cm, blade lanceolate-elliptic or very narrowly elliptic to linear, sometimes to oblanceolate or oblanceolate-elliptic near base, 1.8–10 × 0.2–1.3(–2) cm, base narrowly cuneate or attenuate, margins subentire with remote hydathodal glands, rarely minutely papillose-serrulate near apex, apex acute to narrowly acute, leaves on side branches much reduced; bracts much 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. |
sometimes congested, leafy spikes or racemes, flowers solitary in distal leaf axils; bracteoles attached near base of ovary, lanceolate-elliptic or narrowly so, 2.4–4.7 × 0.6–1.5 mm, margins minutely papillose or smooth, apex acute, surfaces glabrous. |
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 spreading to reflexed, creamy white adaxially, broadly ovate-deltate, 2–4 × 1.6–4 mm, margins smooth or minutely papillose-serrulate, apex acute or acuminate, surfaces glabrous; petals 0; filaments nearly translucent, 1.1–1.7 mm, slightly dilated near base, anthers 0.5–0.9 × 0.4–0.7 mm; pollen shed singly; ovary obpyramidal, sharply 4-angled, 2–3.8 × 2–3.5 mm; nectary disc elevated 0.5–0.8 mm on ovary apex, bright yellow, square with rounded corners, 2–3.3 mm diam., prominently 4-lobed, glabrous; style pale green, 0.8–1.3 mm, glabrous, stigma pale yellow, subglobose, 0.3–0.6 × 0.3–0.7 mm, shallowly 4-lobed on top, not exserted beyond anthers. |
Capsules | obconic, obscurely 4-angled, 1.5–2.5 × 1.5–3 mm, hard-walled, dehiscent by loculicidal slits, pedicel 0–0.4 mm. |
obpyramidal, sharply 4-angled and 4-winged, 3–5 × 2.8–4.5 mm, with hard walls somewhat bulging, dehiscent by apical ring, pedicel 0–0.8 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. |
light brown, ellipsoid, slightly curved on both ends, 0.6–0.7 × 0.3–0.4 mm, surface cells elongate transversely to seed length. |
2n | = 48. |
= 48. |
Ludwigia simpsonii |
Ludwigia alata |
|
Phenology | Flowering Apr–Nov (year-round). | Flowering Jun–Oct. |
Habitat | Sandy, peaty ditches, open pineland swamps, edges of cypress swamps, tidal flats and nearby marshes, limestone sinks. | Ditches, edges of ponds and lagoons, peaty or sandy swales, open cypress swamps, sandy borrow pits in open pine woods, swampy, flat outcrops of oolitic rocks, wet savannas, tidal flats, brackish marshes, sandy beach strands and hammocks. |
Elevation | 0–50 m. (0–200 ft.) | 0–50 m. (0–200 ft.) |
Distribution |
FL; MS; West Indies (Cuba, Jamaica) |
AL; FL; GA; LA; MS; NC; SC; VA; West Indies (Jamaica) |
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 alata occurs only at very low elevations along the Atlantic and Gulf coastal plains from Virginia to the tip of Florida, and west to southwestern Louisiana, with disjunct populations on Jamaica (C. I. Peng 1989). This hexaploid species is often confused with L. lanceolata, with which it shares two genomes (Peng 1988, 1989) and with which it is frequently sympatric. The showy petals of L. alata suggest a higher level of outcrossing, and numerous natural hybrids have been documented (Peng 1988, 1989). (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 | Isnardia alata |
Name authority | Chapman: Fl. South. U.S. ed. 2 repr. 2, 685. (1892) — (as simpsoni) | Elliott: Sketch Bot. S. Carolina 1: 212. (1817) |
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