Ludwigia polycarpa |
Ludwigia virgata |
|
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false loosestrife, many-fruit water-primrose, manyfruit primrose-willow |
savannah primrose-willow |
|
Habit | Herbs slender, with well-developed aerenchyma on submerged stems, forming stolons 2.5–15(–22) cm, 1–2.3 mm thick, well branched. | |
Roots | fascicled, often fusiform, or spreading horizontally. |
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Stems | erect or ascending, slightly ridged, well branched, (10–)25–60(–85) cm, glabrate with raised ± strigillose lines decurrent from leaf axils. |
subterete to scarcely angled, with narrow raised lines or wings decurrent from leaf axils, 45–85 cm, branched mainly near base, glabrate with strigillose raised lines or strigillose. |
Leaves | alternate; stipules narrowly to broadly ovate, 0.1–0.4 × 0.1–0.3 mm; stolons: leaves often clustered near apex of stolon, petiole 0–0.5 cm, blade narrowly elliptic or oblanceolate, 0.8–2(–3.2) × 0.2–0.8(–1.2) cm, base attenuate, margins entire or remotely denticulate, apex acute, surfaces glabrous; stems: petiole winged, 0.1–1 cm, blade very narrowly oblong-elliptic, 3.5–11 × 0.4–1(–1.7) cm, base very narrowly cuneate or long-attenuate, margins entire and densely, minutely papillose-serrulate with obscure hydathodal glands, apex narrowly acute or acuminate, surfaces glabrous; bracts not much reduced. |
stipules narrowly deltate, 0.1–0.2 × 0.1–0.15 mm; sessile; blade ovate to obovate proximally, lanceolate-linear to linear distally, 2–7 × 0.2–1(–1.5) cm, base cuneate, margins entire, apex acute to rounded, surfaces strigillose, densely so particularly along veins; bracts usually very reduced in size, sublinear. |
Inflorescences | elongated, leafy spikes, flowers solitary in leaf axils, sometimes borne almost to base of stems; bracteoles attached 0.5–2.5(–3) mm distal to base of ovary, linear-lanceolate, 3.5–6.5(–8) × 0. |
sparse racemes, flowers solitary in leaf axils; bracteoles attached in subopposite pairs on distal 1/3 of pedicel, lanceolate-linear, 0.7–3.2(–5) ×0.2–0.5 mm, margins entire, apex acute, surfaces strigillose. |
Flowers | sepals spreading horizontally with reflexed tips, pale green, narrowly ovate-deltate, 2.5–4.5 × 1.5–3.2 mm, margins entire, minutely papillose-serrulate, apex elongate-acuminate, surfaces glabrous; petals 0; filaments yellowish green, 0.7–1.5 mm, base dilated, anthers 0.5–0.9 × 0.5–0.7 mm; pollen shed in tetrads; ovary oblong, barely 4-angled, 3–4.5 × 2–3.5 mm; nectary disc elevated 0.5–0.8 mm on ovary apex, yellowish green, 1.8–3 mm diam., 4-lobed, glabrous; style yellowish green, 0.5–0.8 mm, glabrous, stigma broadly clavate to subglobose, 0.4–0.8 × 0.3–0.6 mm, usually 4-lobed, not exserted beyond anthers. |
sepals strongly reflexed, narrowly ovate-deltate, 6–10 × 2.5–4.5 mm, margins entire, apex acute, surfaces finely strigillose to glabrate; petals cordate, 14–19 × 13–15 mm, base attenuate, apex emarginate; filaments opaque white, awl-shaped, 1.9–4.2 mm, anthers 2–4 × 0.6–1 mm; ovary subcuboid to globose, 3–4 × 3–4 mm; nectary disc elevated, domed, 0.8–1.4 mm diam., prominently 4-lobed, ringed with silky-curly hairs; style 5–9.5 mm, glabrous, stigma capitate to hemispherical, 0.6–1.3 × 1.3–2.6 mm, shallowly 4-lobed, as long as or exserted beyond anthers. |
Capsules | oblong-obovoid, obscurely 4-angled, 4–7 × 2.5–5 mm, hard-walled, irregularly dehiscent, pedicel 0.1–0.3 mm. |
subglobose to ellipsoid, 3.5–6.8 × 3.3–4.3 mm, 4-angled, angles not developed into wings, pedicel 6.5–17 mm. |
Seeds | light brown, narrowly oblong with curved ends, 0.5–0.6 × 0.2–0.3 mm, surface cells elongate parallel to seed length. |
light brown, elliptic-oblong to reniform, 0.5–0.7 × 0.3–0.4 mm, surface cells elongate transversely to seed length or elongate parallel to length near raphe. |
4 | –1(–1.3) mm, with a swollen base, margins minutely papillose-serrulate. |
|
2n | = 32. |
= 16. |
Ludwigia polycarpa |
Ludwigia virgata |
|
Phenology | Flowering Jun–Sep. | Flowering summer. |
Habitat | Ditches, moist prairies, alluvial ground of ponds, lakes, and rivers, marshes, swales, edges of lagoons, low fallow fields. | Sandy savannas, pinelands, damp roadside ditches, margins of ponds, bogs, irrigated fields, usually within 75 miles of sea coast. |
Elevation | 100–300 m. (300–1000 ft.) | 0–300 m. (0–1000 ft.) |
Distribution |
CT; IA; ID; IL; IN; KS; KY; MA; MI; MN; MO; NE; OH; PA; VA; WI; WV; ON
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AL; FL; GA; MS; NC; SC; VA
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Discussion | Ludwigia polycarpa, unlike all other species in sect. Isnardia, is distributed primarily in the central Midwest and Great Lakes regions, with one highly disjunct population recorded from Kootenai County, Idaho, which is presumably introduced. This species has also been found scattered as far east as Connecticut and Massachusetts, and reports of it from Arkansas, Maine, Tennessee, and Vermont cannot be confirmed. As indicated by C. I. Peng (1989), a report of this species from Alabama involved a natural hybrid between L. glandulosa and L. pilosa. The basal stolons formed by Ludwigia polycarpa tend to be shorter, more condensed, and more branched than those found in other species, and may be a morphological adaptation to perennial survival in the colder areas in which it grows. (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. Ludwigia |
Sibling taxa | ||
Synonyms | Isnardia polycarpa | Isnardia virgata |
Name authority | Short & R. Peter: Transylvania J. Med. Assoc. Sci. 8: 581. (1835) | Michaux: Fl. Bor.-Amer. 1: 89. (1803) |
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