Ludwigia bonariensis |
Ludwigia arcuata |
|
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Carolina primrose-willow |
Piedmont primrose-willow |
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Habit | Herbs, from woody rootstock. | Herbs usually creeping and rooting at nodes, forming mats. |
Stems | erect, subterete, 20–120 cm, branched, glabrate proximally, or strigillose, especially in distal parts, with raised strigillose lines decurrent from leaf axils mid stem. |
prostrate or decumbent and ascending at tips, slightly ridged, often well branched, 5–70 cm, glabrate to sparsely strigillose, denser on distal parts. |
Leaves | stipules narrowly deltate, 0.3–0.5 × 0.1–0.2 mm; petiole winged, 0.1–0.7 cm; blade narrowly to broadly lanceolate, 4–15 × 0.3–1(–3) cm, base tapered, margins subentire to inconspicuously glandular-serrulate, apex acute to acuminate, surfaces finely strigillose, especially on abaxial veins, sometimes glabrate; bracts narrower, reduced in size. |
opposite; stipules narrowly deltate or ovate, 0.05–0.15 × 0.05–0.1 mm; submerged stems: petiole 0–0.2 cm, blade narrowly linear, 1.9–4 ×0.1–0.25 cm; emergent stems: petiole 0–0.2 cm, blade narrowly elliptic or narrowly oblanceolate-elliptic to linear, 0.6–1.8 × 0.2–0.5 cm, base narrowly cuneate, margins entire, apex acute, surfaces glabrous or sparingly strigillose on margins and abaxial midveins; bracts reduced. |
Inflorescences | open, leafy racemes, flowers solitary in axils; bracteoles lanceolate-linear or setaceous, 2–6 × 0.3–0.8 mm, attached on pedicel just proximal to base of ovary. |
in racemes or spikes, well-formed on ascending stems, not on prostrate stems; bracteoles attached at base of ovary or 1.5–8 mm proximally on pedicels, sublinear to very narrowly elliptic, 1.4–5 × 0.2–0.8 mm, apex acute, surfaces minutely strigillose. |
Flowers | sepals ovate-deltate, 10–20 × 7–12 mm, abruptly acuminate or acute, inconspicuously 5–7-nerved, surfaces strigillose; petals deep golden yellow, broadly obovate, 20–35 × 10–30 mm, apex shallowly emarginate, claw 1.5–3 mm; stamens 8 in 2 unequal series, filaments flattened and dilated near base, epipetalous set 3.4–4.5 mm, episepalous set 4.5–5.5 mm, anthers oblong, 4–5 mm; pollen shed in polyads; ovary subcylindric, slightly 4-angled, 8–12(–20) mm; nectary disc slightly elevated on ovary apex, 2–3 mm diam., 4-lobed, ringed by short hairs; style 3–3.5 mm, stigma clavate-capitate, 2.5–3 × 2–2.5 mm, often exserted beyond anthers. |
sepals reflexed or spreading, green, lanceolate-deltate, 5.2–10 ×1.5–2.7 mm, with 3 prominent parallel veins, margins entire and minutely strigillose, apex acute or elongate-acuminate, surfaces minutely strigillose abaxially; petals rarely caducous, elliptic-obovate to spatulate-obovate, 7–11 × 4.5–8 mm, base attenuate, apex rounded; filaments initially spreading, becoming erect, yellow, 2.5–4.5 mm, anthers 1.3–2 × 0.7–1.1 mm; pollen shed in tight tetrads; ovary cylindric to funnelform, 4–5.5 × 1.5–2.8 mm; nectary disc elevated 0.6–1 mm on ovary apex, 1.5–2.6 mm diam., bright yellow, with 4 distinct domed lobes, minutely strigillose between lobes or glabrous; style yellow, 2.3–4(–4.8) mm, glabrous, stigma yellow, broadly capitate, 0.3–0.6 × 0.6–1.8 mm, as long as or exserted beyond anthers. |
Capsules | clavate-cylindric, subterete to obtusely 4-angled, 20–35 × 3.5–5 mm, thin walls, irregularly dehiscent, tapering to pedicel 10–40 mm. |
clavate, subterete, sometimes slightly curved, 5.5–10 × 2.3–4 mm, hard-walled, irregularly dehiscent, pedicel (12–)17–45 mm. |
Seeds | in several indistinct rows per locule, yellow-brown, oblong (appearing round), 0.5 mm, shiny, raphe 2/3 as wide as body. |
light to dark brown, elliptic-oblong, 0.5–0.7 × 0.3–0.4 mm, surface cells transversely elongate. |
2n | = 16. |
= 32. |
Ludwigia bonariensis |
Ludwigia arcuata |
|
Phenology | Flowering summer. | Flowering Mar–Aug. |
Habitat | Wet places, mainly along coastal areas, especially ditches, banks near brackish water. | Roadside ditches, edges of lakes or ponds, swampy prairies, springs, mucky or sandy beach strands. |
Elevation | 0–200[–2600] m. (0–700[–8500] ft.) | 0–150 m. (0–500 ft.) |
Distribution |
AL; FL; MS; NC; SC; TX; Mexico (Chihuahua, Durango, Puebla, Quintana Roo, Tabasco, Tamaulipas, Veracruz); South America (Argentina, Bolivia, Brazil, Paraguay, Uruguay)
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AL; FL; GA; SC |
Discussion | Ludwigia arcuata is common in its range, but geographically restricted to central and western parts of peninsular Florida and adjacent Georgia, extending to southern South Carolina. Disjunct populations have been collected in Bibb County in central Georgia and Mobile County, Alabama. The tetraploid Ludwigia arcuata has the largest flowers in sect. Isnardia and is the most consistently outcrossing species; C. I. Peng (1989) reported abundant insect visitors on this species. It is morphologically most similar to the hexaploid L. brevipes, with which it shares two genomes (Peng). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 10. | FNA vol. 10. |
Parent taxa | Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Macrocarpon | Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Isnardia |
Sibling taxa | ||
Synonyms | Jussiaea bonariensis, J. neglecta, J. suffruticosa var. bonariensis | Isnardia arcuata, I. pedunculosa, L. pedunculosa, Ludwigiantha arcuata |
Name authority | (Micheli) H. Hara: J. Jap. Bot. 28: 291. (1953) | Walter: Fl. Carol., 89. (1788) |
Web links |