Ludwigia peploides
Ludwigia sect. Jussiaea
creeping water primrose, floating primrose-willow, marsh purslane
floating or creeping and ascending to erect, terete, 10–100(–300) cm, simple or branched, glabrous or sparsely to densely villous, hairs sometimes viscid on emergent distal stem.
decumbent to erect or ascending, terete, sometimes angled distally.
stipules broadly ovate-deltate, 0.6–1.6 × 0.4–1 mm, succulent, apex acute or obtuse, gland-tipped, rarely divided into 3 parts;
petiole flattened or narrowly winged, 0.2–6 cm;
blade narrowly oblong or elliptic to ovate, broadly obovate, or orbiculate, (0.4–)1–10 × 0.4–4 cm, base narrowly cuneate or attenuate, margins entire, apex obtuse or rounded to acute, sometimes mucronate or glandular-mucronate, surfaces of floating leaves glabrous, those of emergent leaves glabrous to sparsely or densely strigillose at least adaxially;
bracts scarcely reduced.
alternate or fascicled.
on emergent stems sometimes in leafy racemes, flowers solitary in leaf axils;
bracteoles (rarely absent), deltate, squamate, 0.5–1 × 0.5–1 mm, apex acute, attached near base or on lower 1/2 of ovary.
sepals narrowly deltate or lanceolate, 3–12 × 1.5–4 mm, apex acute or acuminate, surfaces glabrous or sparsely to densely hirtellous;
petals yellow, obpyramidal,7–24 × 4–13 mm, apex mucronate or emarginate, up-curved;
stamens 10(or 12), in 2 unequal series, bright yellow, filaments suberect or reflexed, shorter ones 1.4–4.2 mm, longer ones (1.9–)3.3–6 mm, anthers oblong, 0.5–2.2 mm;
ovary subcylindric or truncate, 6–20 × 1.5–3 mm, apex somewhat broader, glabrous or sparsely to densely hirtellous;
nectary disc slightly raised on ovary apex, 2–2.5 mm diam., lobed, glabrous or fringed with long hairs;
style (1.9–)2.4–7.3 mm, glabrous or sparsely to densely hirtellous on proximal 1/2, stigma flattened-globose, 0.9–1.2 × 1–2.5 mm, sometimes shallowly or deeply 5-lobed, as long as or exserted beyond anthers.
5(or 6)-merous;
petals present, yellow [white];
stamens 2 times as many as sepals, [rarely as many as];
pollen shed as monads.
cylindric, subterete to obscurely 5-angled, straight or curved, 10–40 × 2–4 mm, with thick woody walls, irregularly and tardily dehiscent, pedicel 7–60(–90) mm.
cylindric, subcylindric, or subclavate, terete, subterete, or obscurely angled, often up-curved, with thick, woody walls, irregularly and tardily dehiscent.
embedded in elongated piece of endocarp, 1–1.5 × 0.9–1.3 mm.
in 1 row per locule, pendulous and firmly embedded in woody, coherent segment of endocarp, raphe inconspicuous.
= 16.
= 16, 32, 48, 80, 96.
Ludwigia peploides
Ludwigia sect. Jussiaea
Subspecies 4 (3 in the flora).
Ludwigia peploides consists of four subspecies more or less well defined geographically and morphologically, with three present in the flora area: subsp. glabrescens, subsp. montevidensis, and subsp. peploides (P. H. Raven 1963[1964]); these subspecies have ranges that are mostly distinct. Subspecies peploides has a wide distribution in the New World, from the southern United States south to Argentina. Subspecies glabrescens is widespread in eastern United States. Subspecies montevidensis occurs primarily in southern South America and scattered (probably introduced) in the southern United States, Australia, France, and New Zealand. Subspecies peploides and montevidensis occur together locally in California and Louisiana, where subsp. montevidensis is introduced. The ranges of subsp. glabrescens and peploides come together in Texas.
Subspecies stipulacea (Ohwi) P. H. Raven is known from eastern Asia (e China).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 9 (3 in the flora).
This cosmopolitan polyploid section of nine variable species (11 taxa) includes three diploid species (n = 8), four tetraploids (n = 16), one hexaploid [Ludwigia grandiflora, n = 24; P. H. Raven and W. Tai (1979) reported one anomalous count of n = 48], and one decaploid (L. hexapetala, n = 40; see also G. L. Nesom and J. T. Kartesz 2000). One persistent triploid (2n = 24) hybrid, described as L. ×taiwanensis C. I. Peng [L. adscendens (n = 16) × L. peploides subsp. stipulacea (n = 8); Peng 1990] is widespread in southern China and Taiwan. E. Zardini et al. (1991) reported several other natural hybrids.
Most species of sect. Jussiaea have non-naturalized distributions restricted to the New World. Section Jussiaea differs from most diplostemonous sections by releasing its pollen as monads and having woody, subcylindric capsules with uniseriate, firmly embedded seeds. Most species in sect. Jussiaea are vigorously aquatic, and several (including L. peploides, L. hexapetala, and L. grandiflora) can be invasive weeds in wetlands and wet agricultural areas; the latter two, or all three, species have recently become major invasive species in California, particularly in the Russian and Sacramento river drainages and in the San Diego region, in Arizona (especially Gila and Salt rivers), and in Washington (M. Wood 2006; P. C. Hoch and B. J. Grewell 2012).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Stems usually densely villous, rarely sparsely so; leaf blades not shiny, apices glandular-mucronate; capsules (20–)24–32 mm. | subsp. montevidensis |
1. Stems glabrous or sparely villous; leaf blades shiny, apices usually eglandular-mucronate; capsules 10–40 mm. | → 2 |
2. Principal leaf blades 0.8–4(–8.5) cm; petioles 0.2–2.5 cm; pedicels 10–35 mm; capsules 10–17(–25) mm; seeds 7–14 per locule. | subsp. peploides |
2. Principal leaf blades (2–)4–10 cm; petioles 0.7–6 cm; pedicels 35–90 mm; capsule 25–40 mm; seeds 16–18 per locule. | subsp. glabrescens |
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