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anglestem primrose-willow, anglestem waterprimrose

Habit Herbs, perennial or (robust) annual, or shrubs, often with woody base, when aquatic, forming white pneumatophores from nodes. Herbs, annual or perennial, or shrubs, often forming pneumatophores when submerged.
Stems

usually erect or strongly ascending, rarely floating or creeping, terete to somewhat angled on young branches, 30–250 cm, well branched to sparsely branched or simple, usually villous, often also strigillose, rarely glabrous, with raised lines decurrent from leaf axils.

erect or ascending, terete or angled.

Leaves

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

petiole 0.2–3.5 cm;

blade broadly lanceolate, 3.5–18 × 1–4 cm, base narrowly cuneate, margins subentire, apex acuminate, surfaces hirsute or villous;

bracts slightly to much reduced.

alternate.

Inflorescences

leafy racemes, flowers solitary in axils;

bracteoles often absent, when present, narrowly deltate, 2–3 × 1.2–2.4 mm, attached near ovary base.

Flowers

sepals ovate-deltate, 5.5–11 × 1.5–3 mm, margins entire, apex acuminate, surfaces villous;

petals orange-yellow, obovate, 5–11 × 4–8 mm;

stamens (8 or)10 or 12(or 14), in 2 unequal series, longer filaments 2.5–4.5 mm, shorter ones 1.5–2.5 mm, anthers oblong, 1.2–1.6 × 0.7–1 mm, extrorse;

ovary cylindric, subterete, 10–16 × 2–3 mm, glabrate to strigillose or villous;

nectary disc slightly elevated at ovary apex, 2–4 mm diam., lobed, depressed, surrounded by densely matted white hairs;

style 3–4.5 mm, glabrous, stigma capitate-globose, 1–1.5 × 2–2.5 mm, ± exserted beyond anthers.

(4 or)5 or 6(or 7)-merous;

petals present, orange-yellow;

stamens 2 times as many as sepals;

pollen shed in polyads.

Capsules

obscurely [4 or]5 or 6[or 7]-angled or subterete, straight or curved, 15–50 × 2.5–4 mm, relatively thin-walled, seeds visible as bumps, tardily and irregularly loculicidal, villous, pedicel 2–20 mm.

subcylindric [cylindric], angled or subterete [terete], with relatively thin walls, irregularly dehiscent.

Seeds

in 1 row per locule, horizontal and loosely embedded in an easily detached horseshoe-shaped segment of firm endocarp, pale brown, obovoid, 1–1.2 mm, shiny, finely pitted, raphe much narrower than seed body.

in 1 row per locule, embedded in horseshoe-shaped segment of endocarp from which it easily detaches, raphe inconspicuous.

2n

= 32, 48.

= 32, 48, 64, 80.

Ludwigia leptocarpa

Ludwigia sect. Seminudae

Phenology Flowering summer.
Habitat Wet places, mainly along coastal areas, especially ditches, banks near brackish water.
Elevation 0–200[–1300] m. (0–700[–4300] ft.)
Distribution
from FNA
AL; AR; DE; FL; GA; IL; IN; KY; LA; MD; MO; MS; NC; OH; OK; PA; SC; TN; TX; VA; WV; Central America; South America; Mexico (Campeche, Chiapas, Jalisco, Nayarit, Oaxaca, San Luis Potosí, Tabasco, Tamaulipas, Veracruz); West Indies (Cuba, Hispaniola, Jamaica, Puerto Rico); Africa; Indian Ocean Islands (Madagascar)
[WildflowerSearch map]
[BONAP county map]
c United States; e United States; Mexico; Central America; South America; West Indies; Africa; Indian Ocean Islands (Madagascar)
Discussion

Ludwigia leptocarpa is a globally widespread and morphologically variable species; in the flora area it is distributed widely in wet areas of the southeastern United States. Both tetraploid and hexaploid plants are known, but it is not clear if or how ploidy level is related to the considerable morphological variation, especially in pubescence type and pattern.

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

Species 5 (1 in the flora).

Section Seminudae consists of a polyploid complex of five species (P. H. Raven and W. Tai 1979), one [hexaploid (n = 24) L. africana (Brenan) H. Hara] endemic to Africa, two [hexaploid (n = 24) L. dodecandra (de Candolle) Zardini & P. H. Raven and chromosomally unknown L. quadrangularis (Micheli) H. Hara] endemic to Central America and South America, and two widely distributed multiploids in the New World but present also in Africa. Of the latter, L. affinis (de Candolle) H. Hara (n = 16, 24) occurs only in a small area of West Africa, probably as a recent introduction from South America (Raven 1963[1964]), whereas L. leptocarpa (n = 32, 40) is widespread and possibly native in sub-Saharan Africa. This section is distinctive among the diplostemonous taxa in having uniseriate seeds embedded in loose segments of endocarp. However, sect. Seminudae so far is poorly resolved by molecular analysis (Liu S. H. et al. 2017).

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

Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Seminudae Onagraceae > subfam. Ludwigioideae > Ludwigia
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. 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
Subordinate taxa
Synonyms Jussiaea leptocarpa, J. biacuminata, J. foliosa, J. leptocarpa subsp. angustissima, J. leptocarpa var. angustissima, J. leptocarpa var. meyeriana, J. pilosa, J. pilosa var. robustior, J. schottii, J. surinamensis, J. variabilis, J. variabilis var. meyeriana, J. variabilis var. pilosa, L. leptocarpa var. angustissima, L. leptocarpa var. meyeriana
Name authority (Nuttall) H. Hara: J. Jap. Bot. 28: 292. (1953) P. H. Raven: Reinwardtia 6: 334. (1964)
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