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Carolina primrose-willow

false loosestrife, many-fruit water-primrose, manyfruit primrose-willow

Habit Herbs, from woody rootstock. Herbs slender, with well-developed aerenchyma on submerged stems, forming stolons 2.5–15(–22) cm, 1–2.3 mm thick, well branched.
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.

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, 0.3–0.5 × 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.

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

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.

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 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 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

clavate-cylindric, subterete to obtusely 4-angled, 20–35 × 3.5–5 mm, thin walls, irregularly dehiscent, tapering to pedicel 10–40 mm.

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

Ludwigia polycarpa

Phenology Flowering summer. Flowering Jun–Sep.
Habitat Wet places, mainly along coastal areas, especially ditches, banks near brackish water. Ditches, moist prairies, alluvial ground of ponds, lakes, and rivers, marshes, swales, edges of lagoons, low fallow fields.
Elevation 0–200[–2600] m. (0–700[–8500] ft.) 100–300 m. (300–1000 ft.)
Distribution
from FNA
AL; FL; MS; NC; SC; TX; Mexico (Chihuahua, Durango, Puebla, Quintana Roo, Tabasco, Tamaulipas, Veracruz); South America (Argentina, Bolivia, Brazil, Paraguay, Uruguay)
[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. Macrocarpon Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Isnardia
Sibling taxa
L. alata, L. alternifolia, L. arcuata, 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. 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 Jussiaea bonariensis, J. neglecta, J. suffruticosa var. bonariensis Isnardia polycarpa
Name authority (Micheli) H. Hara: J. Jap. Bot. 28: 291. (1953) Short & R. Peter: Transylvania J. Med. Assoc. Sci. 8: 581. (1835)
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