Ludwigia peploides subsp. montevidensis
Onagraceae subfam. ludwigioideae
floating primrose-willow, floating water primrose
usually densely villous, rarely sparsely so, hairs often viscid when fresh, or glabrate on submerged stems.
alternate, sometimes fascicled;
stipules often asymmetrical;
petioles of basal leaves (0.5–)0.8–1.6 cm, those of distal leaves 0.5–2.8 cm;
blade (0.4–)1–6(–9.5) cm, apex glandular-mucronate, surfaces not shiny, usually densely hirtellous, rarely glabrous abaxially.
stipules present.
anthers on short filaments (0.7–)0.9–1.8 mm, those on long filaments (0.8–)1.1–2.2 mm;
ovary 6–10 mm, apex truncate, densely hirtellous, sometimes only on apical 1/2, stigma usually as long as anthers, rarely exserted beyond them.
floral tube absent;
sepals (3 or)4 or 5(–7), persistent at ovary apex after dehiscence of other floral parts;
petals yellow or white, rarely absent.
(20–)24–32 × 2–4 mm, pedicel 7–38(–60) mm.
10–15 per locule.
= 16 (32).
Ludwigia peploides subsp. montevidensis
Onagraceae subfam. ludwigioideae
In the flora area, subsp. montevidensis is introduced in California (P. H. Raven 1963c), where it was first collected in 1906 (El Dorado County, Rixford s.n., CAS), and in Louisiana. Subspecies montevidensis occasionally forms masses of vegetation that can obstruct water flow and navigation in California and elsewhere.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genus 1, species 82 (31 in the flora): North America, Mexico, West Indies, Bermuda, Central America, South America, se Asia, Africa, Indian Ocean Islands, Pacific Islands, Australasia; introduced in Europe, w Asia.
Ludwigioideae were segregated as a distinct subfamily (W. L. Wagner et al. 2007) to reflect the phylogenetic relationship of Ludwigia as sister to other genera of Onagraceae in morphological and molecular analyses (see R. A. Levin et al. 2003, 2004). Ludwigia is distinguished by the absence of a floral tube, persistence of sepals on capsules after other floral parts dehisce, pollen shed in tetrads or polyads (or as monads in some sections, tetrads sometimes found elsewhere in Onagraceae), double ovule vascular supply, uniquely including a central supply (R. H. Eyde 1981), single-celled ovule archesporium (H. Tobe and P. H. Raven 1996), and a base chromosome number of x = 8.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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