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seaside primrose-willow

false loosestrife, many-fruit water-primrose, manyfruit 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

fibrous or fusiform, sometimes fascicled.

Stems

subterete to scarcely angled, with narrow raised lines or wings decurrent from leaf axils, 30–90 cm, simple or sparsely branched distally, strigillose to sometimes glabrate.

erect or ascending, slightly ridged, well branched, (10–)25–60(–85) cm, glabrate with raised ± strigillose lines decurrent from leaf axils.

Leaves

stipules narrowly deltate, 0.05–0.2 × 0.05–0.1 mm;

sessile;

blade ovate proximally, lanceolate to lanceolate-linear distally, (2–)3–8 × 0.3–1.5 cm, base cuneate, margins entire, apex acute, surfaces glabrate to strigillose or hirsute;

bracts usually much reduced, sublinear.

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.

Inflorescences

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.

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.

Flowers

sepals often spreading, ovate-deltate, (4.5–)5.5–8(–9) × 3–5 mm, margins entire, apex acute to obtuse, surfaces strigillose;

petals cordate, 9–12 × 8–10 mm, base attenuate, apex emarginate;

filaments yellow, awl-shaped, 1.9–3.2 mm, anthers 1.2–2.5 × 0.4–0.7 mm;

ovary subcuboid or globose, 3–4.5 × 3–4 mm;

nectary disc elevated, domed, 0.9–1.3 mm diam., prominently 4-lobed, ringed with sparse, spreading hairs;

style 1.5–3.3 mm, glabrous, stigma capitate to hemispherical, 0.6–1.2 × 1.4–1.9 mm, shallowly 4-lobed, not exserted beyond anthers.

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.

Capsules

subcuboid to squarish globose, 4–7 ×4–5 mm, 4-angled, often also 4-winged, wings 0.3–1.2 mm wide, pedicel 5–17 mm.

oblong-obovoid, obscurely 4-angled, 4–7 × 2.5–5 mm, hard-walled, irregularly dehiscent, pedicel 0.1–0.3 mm.

Seeds

light brown, oblong to reniform, 0.4–0.6 ×0.2–0.4 mm, surface cells elongate transversely to seed length, except may be parallel to seed length near raphe.

light brown, narrowly oblong with curved ends, 0.5–0.6 × 0.2–0.3 mm, surface cells elongate parallel to seed length.

4

–1(–1.3) mm, with a swollen base, margins minutely papillose-serrulate.

2n

= 16.

= 32.

Ludwigia maritima

Ludwigia polycarpa

Phenology Flowering summer. Flowering Jun–Sep.
Habitat Damp, sandy, or peaty habitats, roadside ditches, margins of bogs or fields, usually within 75 miles of sea coast. Ditches, moist prairies, alluvial ground of ponds, lakes, and rivers, marshes, swales, edges of lagoons, low fallow fields.
Elevation 0–200 m. (0–700 ft.) 100–300 m. (300–1000 ft.)
Distribution
from FNA
AL; FL; GA; LA; MS; NC; SC
[WildflowerSearch map]
[BONAP county map]
from FNA
CT; IA; ID; IL; IN; KS; KY; MA; MI; MN; MO; NE; OH; PA; VA; WI; WV; ON
[WildflowerSearch map]
[BONAP county map]
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. Ludwigia Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Isnardia
Sibling taxa
L. alata, L. alternifolia, L. arcuata, L. bonariensis, L. brevipes, L. curtissii, L. decurrens, L. erecta, L. glandulosa, L. grandiflora, L. hexapetala, L. hirtella, L. lanceolata, L. leptocarpa, L. linearis, L. linifolia, L. microcarpa, L. octovalvis, L. palustris, L. peploides, L. peruviana, L. pilosa, L. polycarpa, L. ravenii, L. repens, L. simpsonii, L. spathulata, L. sphaerocarpa, L. suffruticosa, L. virgata
L. alata, L. alternifolia, L. arcuata, L. bonariensis, L. brevipes, L. curtissii, L. decurrens, L. erecta, L. glandulosa, L. grandiflora, L. hexapetala, L. hirtella, L. lanceolata, L. leptocarpa, L. linearis, L. linifolia, L. maritima, L. microcarpa, L. octovalvis, L. palustris, L. peploides, L. peruviana, L. pilosa, L. ravenii, L. repens, L. simpsonii, L. spathulata, L. sphaerocarpa, L. suffruticosa, L. virgata
Synonyms Isnardia polycarpa
Name authority R. M. Harper: Torreya 4: 163, fig. 2. (1904) Short & R. Peter: Transylvania J. Med. Assoc. Sci. 8: 581. (1835)
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