Ludwigia simpsonii |
Ludwigia curtissii |
|
---|---|---|
Simpson's primrose-willow |
Curtiss' primrose-willow |
|
Habit | Herbs sometimes creeping and rooting at nodes, new shoots arising from trailing stems or main caudex, rarely forming stolons. | Herbs rarely creeping and rooting at nodes, stolons usually absent. |
Stems | erect, ascending, decumbent, or prostrate, slightly ridged, well branched, 10–60(–75) cm, glabrous, with raised lines decurrent from leaf axils. |
erect or ascending at base, very rarely prostrate, unbranched to well branched, branches sometimes very slender, 15–75 cm, glabrous, with slightly raised lines decurrent from leaf axils. |
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 reddish purple, narrowly ovate, 0.2–0.3 × 0.1–0.3 mm, succulent; petiole winged, 0.3–1.2 cm, blade usually oblanceolate-spatulate to spatulate or oblanceolate, rarely sublinear, 1–2.5(–3) × 0.1–0.8 cm, base attenuate, margins subentire with hydathodal glands, apex acute or mucronate, surfaces glabrous; bracts not 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. |
usually not congested, leafy racemes or spikes, flowers solitary in leaf axils; bracteoles attached in opposite pairs near base of ovary, narrowly lanceolate, lanceolate-elliptic, or oblong-linear, 1.5–3.5(–4) × 0.4–0.8 mm, swollen at base, apex acuminate. |
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 ascending, green fading to white near base, ovate-deltate, 1.5–3 × 1.2–2 mm, margins entire, apex narrowly acute or acuminate, surfaces glabrous; petals 0(–3), narrowly elliptic or spatulate, 1–2.5 × 0.5–1 mm, base attenuate, apex obtuse; filaments pale yellow, 0.8–1(–1.3) mm, anthers 0.3–0.6 × 0.3–0.5 mm; pollen shed singly; ovary obovate-obpyramidal, 2–2.5 × 1.8–2.3 mm, glabrous; nectary disc elevated 0.3–0.4 mm on ovary apex, green, 0.9–1.6 mm diam., prominently 4-lobed, glabrous; style pale green, 0.4–0.7 mm, glabrous, stigma pale yellow, subglobose, 0.3–0.4 × 0.2–0.4 mm, 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. |
obconic, obscurely 4-angled, (2–)2.5–4(–4.7) × 2–3(–3.5) mm, hard-walled, dehiscent by loculicidal slits, pedicel 0.1–0.5 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, 0.4–0.6 × 0.3–0.4 mm, surface cells transversely elongate, glabrous or, sometimes, with surface wax that mimics appressed hairs. |
2n | = 48. |
= 64. |
Ludwigia simpsonii |
Ludwigia curtissii |
|
Phenology | Flowering Apr–Nov (year-round). | Flowering Mar–Nov (year-round). |
Habitat | Sandy, peaty ditches, open pineland swamps, edges of cypress swamps, tidal flats and nearby marshes, limestone sinks. | Pine savannas and flatwoods, marshes, edges of ponds and streams, sandy or peaty swales, limestone prairies, solution pits on limestone. |
Elevation | 0–50 m. (0–200 ft.) | 0–50 m. (0–200 ft.) |
Distribution |
FL; MS; West Indies (Cuba, Jamaica) |
FL; West Indies (Bahamas) |
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 curtissii is the only octoploid (n = 32) in sect. Isnardia, and is restricted to peninsular Florida and the Bahamas. It and L. simpsonii they are the only members of the section that do not form true stolons; instead they simply sprout new shoots from the base. The two species are similar in many ways and appear to share three genomes (C. I. Peng 1988). (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 | L. spathulifolia |
Name authority | Chapman: Fl. South. U.S. ed. 2 repr. 2, 685. (1892) — (as simpsoni) | Chapman: Fl. South. U.S. ed. 2, 621. (1883) |
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