Ludwigia polycarpa |
Ludwigia glandulosa |
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false loosestrife, many-fruit water-primrose, manyfruit primrose-willow |
creeping seedbox, cylindricfruit primrose-willow |
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Habit | Herbs slender, with well-developed aerenchyma on submerged stems, forming stolons 2.5–15(–22) cm, 1–2.3 mm thick, well branched. | Herbs slender, forming stolons 5–20 cm, 0.4–0.8 mm thick. | ||||
Stems | erect or ascending, slightly ridged, well branched, (10–)25–60(–85) cm, glabrate with raised ± strigillose lines decurrent from leaf axils. |
erect, slightly ridged, usually well branched, 10–80(–100) cm, glabrate or often with strigillose raised lines decurrent from leaf axils. |
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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. |
alternate; stipules ovate-triangular, 0.15–0.35 × 0.05–0.25 mm, succulent; stolons: petiole attenuate, 0.3–1 cm, blade narrowly elliptic, 1.5–3.5(–5.5) × 0.5–1.3(–2) cm; main stem: petiole 0–1.5 cm, blade usually narrowly elliptic to elliptic, sometimes linear, 3–12 × 0.3–2.1 cm, base attenuate, margins subentire with hydathodal glands often visible, apex acute to very narrowly acute, surfaces densely papillose-strigillose, abaxial veins glabrous or sparingly, minutely strigillose; leaves on side branches usually reduced, 0.8–4.5 ×0.2–1 cm; bracts much reduced. |
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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. |
open, leafy racemes or spikes, flowers solitary in axils, often congested, especially on branches; bracteoles attached on pedicel at base of ovary or to 2 mm distal to base, narrowly lanceolate to sublinear, 0.4–1 × 0.1–0.4 mm, apex acuminate, surfaces glabrate. |
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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 ascending, light green, ovate-deltate, 1.1–2.3 × 1–1.8 mm, margins entire, fringed with minute, strigillose hairs, apex short-acuminate or acute, surfaces glabrous; petals 0; filaments nearly translucent, 0.6–1.1 mm, anthers 0.3–0.5 × 0.3–0.6 mm; pollen shed in tetrads; ovary subcylindric, 2–5 × 0.8–1.9 mm; nectary disc elevated 0.3–0.4 mm on ovary apex, light green, 0.6–1.8 mm diam., 4-lobed, glabrous or minutely papillose; style pale green, 0.3–0.8 mm, glabrous, stigma broadly clavate to subglobose, 0.2–0.5 × 0.2–0.5 mm, not exserted beyond anthers. |
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Capsules | oblong-obovoid, obscurely 4-angled, 4–7 × 2.5–5 mm, hard-walled, irregularly dehiscent, pedicel 0.1–0.3 mm. |
subcylindric, subterete to obscurely 4-angled with 4 shallow grooves, 2–8(–9) × 1.3–2(–3) mm, hard-walled, irregularly dehiscent, pedicel 0–0.3(–0.5) mm. |
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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, kidney-shaped with slightly pointed ends, 0.5–0.8 × 0.3–0.4 mm, surface cells columnar, elongate either parallel or transversely to seed length. |
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4 | –1(–1.3) mm, with a swollen base, margins minutely papillose-serrulate. |
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2n | = 32. |
= 32. |
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Ludwigia polycarpa |
Ludwigia glandulosa |
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Phenology | Flowering Jun–Sep. | |||||
Habitat | Ditches, moist prairies, alluvial ground of ponds, lakes, and rivers, marshes, swales, edges of lagoons, low fallow fields. | |||||
Elevation | 100–300 m. (300–1000 ft.) | |||||
Distribution |
CT; IA; ID; IL; IN; KS; KY; MA; MI; MN; MO; NE; OH; PA; VA; WI; WV; ON
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c United States; e United States
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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.) |
Subspecies 2 (2 in the flora). Ludwigia glandulosa consists of two subspecies: subsp. glandulosa is very common and widespread throughout the Atlantic and Gulf coastal plains and the Mississippi Embayment, westward to eastern Texas and southeastern Oklahoma; subsp. brachycarpa grows only in the western portion of the range of subsp. glandulosa, extending farther west in Texas and Oklahoma. The two taxa grow in similar habitats, but subsp. glandulosa prefers drier habitats farther south and west. The general distinctiveness of these subspecies is probably maintained by their modal autogamy; vegetative reproduction by means of stolons may likewise play a role in preserving favored genotypes (C. I. Peng 1989). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 10. | FNA vol. 10. | ||||
Parent taxa | Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Isnardia | Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Isnardia | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Isnardia polycarpa | |||||
Name authority | Short & R. Peter: Transylvania J. Med. Assoc. Sci. 8: 581. (1835) | Walter: Fl. Carol., 88. (1788) | ||||
Web links |