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false loosestrife, large-flower primrose-willow, primrose willow, six petal water primrose, Uruguayan primrose-willow, water primrose

seaside primrose-willow

Habit Herbs, subshrubs, or emergent aquatics, adventitious roots sometimes forming a thick mass 10–23 cm at submerged nodes, sometimes woody at base, white pneumatophores 5–10 cm often on submerged stems.
Roots

fibrous or fusiform, sometimes fascicled.

Stems

floating or creeping and ascending to erect, terete, 20–200(–400) cm, simple to densely branched apically, glabrous (floating) or sparsely to densely villous (emergent), sometimes villous only on inflorescence.

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.

Leaves

stipules ovate or deltate, 0.7–2 × 0.5–1.1 mm, not succulent, apex subacute, mucronate;

petiole flattened, 0.5–2(–2.5) cm;

blade narrowly oblanceolate, narrowly elliptic, or lanceolate to obovate or spatulate, (1.5–)4.2–10.7(–13.5) × (0.5–)0.8–3 cm, chartaceous, base cuneate or attenuate, margins entire, apex acute to obtuse, rounded or truncate, sometimes mucronate, surfaces not shiny, usually glabrous, sometimes villous on petiole and veins or throughout;

bracts not reduced.

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.

Inflorescences

emergent stems sometimes in leafy racemes, sometimes reflexed, flowers solitary in leaf axils;

bracteoles obovate to narrowly obovate, 1–1.8 × 0.7–0.8 mm, apex acute or acuminate, attached on distal 1/2 of pedicel or at ovary base.

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 ovate-deltate or lanceolate-deltate, (8–)12–19 × 2–5 mm, chartaceous, margins entire, apex acuminate, surfaces ± densely villous;

petals bright yellow, sometimes with orange base, fan-shaped, (15–)20–30 × (12–)16–25 mm, apex emarginate or mucronate;

stamens 10(or 12), in 2 unequal series, yellow, filaments recurved, shorter ones (1.6–)2.3–5.2 mm, longer ones (3.1–)3.6–7.5 mm, anthers oblong, (1.2–)1.7–4 × 1–1.5 mm;

ovary subcylindric, terete, 10–18 × 2–3 mm, apex ± broadened, glabrous or sparsely to densely villous;

nectary disc slightly raised on ovary apex, yellowish green, 2–4 mm diam., lobed, glabrous or ringed with white hairs;

style yellow, 6–10 mm, glabrous, stigma subcapitate-globose, 0.5–1.5 × 1.5–2.5 mm, often exserted beyond anthers.

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.

Capsules

cylindric or subclavate, terete, sometimes curved, (12–)16–24(–30)× 2.5–4 mm, with thick woody walls, irregularly and tardily dehiscent, pedicel (9–)13–25(–85) mm.

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.

Seeds

embedded in wedge-shaped piece of endocarp, 0.8–1 × 0.8–1 mm.

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.

2n

= 80.

= 16.

Ludwigia hexapetala

Ludwigia maritima

Phenology Flowering spring–late fall. Flowering summer.
Habitat Wet places, along slow-moving rivers, streams, canals, ditches, often growing into main channel as aquatic weed. Damp, sandy, or peaty habitats, roadside ditches, margins of bogs or fields, usually within 75 miles of sea coast.
Elevation 0–200[–2600] m. (0–700[–8500] ft.) 0–200 m. (0–700 ft.)
Distribution
from FNA
AL; AR; CA; FL; GA; KY; LA; MS; NC; NY; OR; PA; SC; TN; WA; Central America (Costa Rica); South America (Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Paraguay, Peru, Uruguay) [Introduced in w Europe (Belgium, France, Spain)]
[WildflowerSearch map]
from FNA
AL; FL; GA; LA; MS; NC; SC
[WildflowerSearch map]
[BONAP county map]
Discussion

Ludwigia hexapetala (2n = 80) was formerly included with L. grandiflora (2n = 48) in L. uruguayensis (Cambessèdes) H. Hara, and some authors (G. L. Nesom and J. T. Kartesz 2000) still consider them to be a single species. The small but consistent morphological differences and different ploidy levels argue for keeping them distinct at the species level.

Fernald described Jussiaea michauxiana (1944), since he thought that J. grandiflora Michaux (1803) was a homonym (not J. grandiflora Ruíz & Pavon). However, it was later determined that the volume containing the Ruíz & Pavon name was published in 1830 (not 1802) making the name by Michaux valid and legitimate, and the name by Fernald an illegitimate substitution. Plants now known as Ludwigia hexapetala were included in the circumscription of L. uruguayensis (Cambessèdes) H. Hara (based on J. uruguayensis Cambessèdes) by P. H. Raven (1963[1964]) and P. A. Munz (1965).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Jussiaea Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Ludwigia
Sibling taxa
L. alata, L. alternifolia, L. arcuata, L. bonariensis, L. brevipes, L. curtissii, L. decurrens, L. erecta, L. glandulosa, L. grandiflora, 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. 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. 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
Synonyms Jussiaeahexapetala hooker, J. repens var. major, L. grandiflora subsp. hexapetala, L. grandiflora var. hexapetala, L. uruguayensis var. major
Name authority (Hooker & Arnott) Zardini, H. Y. Gu & P. H. Raven: Syst. Bot. 16: 243. (1991) R. M. Harper: Torreya 4: 163, fig. 2. (1904)
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