View source for Ludwigia ← Ludwigia You do not have permission to edit this page, for the following reason: The action you have requested is limited to users in the group: Users. You can view and copy the source of this page. {{Treatment/ID |accepted_name=Ludwigia |accepted_authority=Linnaeus |publications={{Treatment/Publication |title=Sp. Pl. |place=1: 118 |other_info_on_pub=(as Ludvigia), [1204]. 1753 }} |common_names=Water-primrose;primrose-willow;false loosestrife |basionyms= |synonyms= |hierarchy=Onagraceae;Onagraceae subfam. Ludwigioideae;Ludwigia |hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Onagraceae]]</div><div class="higher-taxon"><small>subfamily</small>[[Onagraceae subfam. Ludwigioideae]]</div><div class="higher-taxon"><small>genus</small>[[Ludwigia]]</div></div> |etymology=For Christian Gottlieb Ludwig, 1709–1773, botanist and physician of Leipzig |volume=Volume 10 |mention_page= |treatment_page= }}<!-- --><span class="statement" id="st-d0_s0" data-properties="herb duration;herb duration;herb architecture;herb pubescence;herb pubescence;herb pubescence;herb pubescence;herb pubescence;herb pubescence"><b>Herbs,</b> usually perennial, rarely annual, or shrubs, [rarely trees], caulescent, usually glabrous, strigillose, villous, or hirtellous, rarely glandular-puberulent.</span> <span class="statement" id="st-d0_s1" data-properties="stem orientation;stem orientation;stem orientation;stem orientation;stem architecture;stem growth form or location;part location;part shape;part architecture;aerenchymum texture;pneumatophore shape;pneumatophore coloration;pneumatophore texture"><b>Stems </b>erect to spreading or prostrate and then often rooting at nodes, sometimes floating, submerged parts, when present, sometimes swollen with spongy aerenchyma or bearing inflated, white, spongy pneumatophores, usually branched.</span> <span class="statement" id="st-d0_s2" data-properties="leaf position;leaf arrangement;leaf arrangement"><b>Leaves </b>cauline, usually alternate, rarely opposite;</span> <span class="statement" id="st-d0_s3" data-properties="">stipules present, often deciduous, usually dark reddish green;</span> <span class="statement" id="st-d0_s4" data-properties="stipule presence;stipule duration;stipule coloration;stipule coloration;stipule coloration;stipule architecture;stipule architecture">usually petiolate, sometimes sessile;</span> <span class="statement" id="st-d0_s5" data-properties="blade size;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;blade shape;submarginal vein quantity;submarginal vein prominence;margin architecture or shape;margin architecture or shape;margin architecture or shape">blade usually reduced distally, usually linear to lanceolate, oblong, or obovate, rarely deltate, with 1 [or 2] ± conspicuous submarginal vein [s], margins entire, serrulate, or glandular-serrulate, usually without oil cells.</span> <span class="statement" id="st-d0_s6" data-properties="raceme arrangement;raceme arrangement;raceme arrangement;raceme orientation;raceme orientation;raceme orientation"><b>Inflorescences </b>spikes, racemes, or clusters, solitary or paired in leaf-axils, erect or decumbent and ascending at tip;</span> <span class="statement" id="st-d0_s7" data-properties="bracteole quantity;bracteole prominence;bracteole coloration;bracteole coloration;bracteole shape;bracteole duration;base presence">bracteoles usually 2 and conspicuous, black or dark red, often scalelike, at or near base of ovary, sometimes deciduous early, rarely absent.</span> <span class="statement" id="st-d0_s8" data-properties="flower reproduction;flower architecture;flower architecture;flower architecture"><b>Flowers </b>bisexual, actinomorphic, pedicellate or sessile;</span> <span class="statement" id="st-d0_s9" data-properties="floral-tube presence">floral-tube absent;</span> <span class="statement" id="st-d0_s10" data-properties="sepal duration;sepal coloration;sepal coloration;sepal life cycle;sepal coloration;sepal life cycle;sepal orientation;sepal orientation;sepal orientation">sepals persistent after anthesis or tardily caducous, (3 or) 4 or 5 (–7), green, sometimes yellow or cream, often becoming flushed with red post-anthesis, spreading to suberect;</span> <span class="statement" id="st-d0_s11" data-properties="petal duration;petal quantity;petal atypical quantity;petal quantity;petal presence;petal coloration;petal coloration">petals caducous, usually (3 or) 4 or 5 (–7), sometimes 0, usually yellow, sometimes white, when yellow, then often ultraviolet-reflecting, margins entire;</span> <span class="statement" id="st-d0_s12" data-properties="margin architecture or shape;series quantity;series size or quantity;series quantity;series size;series size">stamens as many as sepals in 1 series, or 2 times as many as sepals in 2 subequal or unequal series;</span> <span class="statement" id="st-d0_s13" data-properties="anther fixation;anther dehiscence;pollen fixation;polyad arrangement;tetrad arrangement">anthers versatile, on smallest flowers appearing basifixed, pollen shed singly or in polyads or tetrads, 3 (–5) -aperturate;</span> <span class="statement" id="st-d0_s14" data-properties="locule quantity;apex shape;apex shape;nectary lobe prominence;nectary lobe shape;base position relational">ovary usually with as many locules as sepals, rarely more, apex flat or conical, often with raised or depressed nectary lobes surrounding base of each epipetalous stamen;</span> <span class="statement" id="st-d0_s15" data-properties="style presence;style pubescence">style present [very rarely absent in sect. Arborescentes], usually glabrous;</span> <span class="statement" id="st-d0_s16" data-properties="stigma shape;stigma shape;stigma shape;stigma shape;stigma shape;stigma shape;stigma shape;stigma shape;stigma position or shape;stigma quantity;surface condition;surface relief">stigma entire or irregularly lobed, capitate or hemispherical, distal 1/2 receptive, surface wet and papillate.</span> <span class="statement" id="st-d0_s17" data-properties="fruit orientation;fruit orientation;fruit orientation;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit shape;fruit course;fruit course;fruit course;fruit dehiscence;fruit dehiscence;capsule orientation;capsule orientation;capsule orientation;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule shape;capsule course;capsule course;capsule course;capsule dehiscence;flap arrangement;flap architecture;flap architecture;flap architecture;apex shape"><b>Fruit </b>a capsule, spreading to erect, obconic, cylindric to clavate, turbinate, obpyramidal, or globose to cuboid, terete to sharply 4+-angled, straight to slightly curved, dehiscent irregularly or by a terminal pore, an apical ring, or flaps separating from valvelike apex, long-pedicellate to subsessile.</span> <span class="statement" id="st-d0_s18" data-properties="seed quantity;seed fusion;seed shape;seed relief;seed relief;row quantity"><b>Seeds </b>50–400, in 1–several rows per locule, usually free, sometimes embedded in endocarp, narrowly ovoid, smooth or finely pitted, raphe usually inconspicuous, sometimes expanded and nearly equal to seed [very rarely expanded into asymmetrical wing].</span> <span class="statement" id="st-d0_s19" data-properties="raphe prominence;raphe size;raphe variability;raphe quantity">= 8.</span><!-- -->{{Treatment/Body |distribution=North America;Mexico;West Indies;Bermuda;Central America;South America;se Asia;Africa;Indian Ocean Islands;Pacific Islands;in Europe;w;s Asia;Australia |discussion=<p>Species 82 (31 in the flora).</p><!-- --><p>Ludwigia is a pansubtropical genus currently divided into 22 sections (P. H. Raven [1963]1964; T. P. Ramamoorthy and E. Zardini 1987; Zardini and Raven 1992; W. L. Wagner et al. 2007). The genus is well represented in North America and South America, and is frequent in Africa and south Asia. Raven provided a synopsis of Ludwigia, including in it all previously segregated genera (Isnardia, Jussiaea, Ludwigiantha, and Oocarpon), based in part on P. A. Munz (1942, 1944), H. Hara (1953), and others. H. E. Baillon (1866–1895, vol. 6) was the first author to merge Isnardia and Jussiaea under Ludwigia, and consequently Ludwigia is treated as having priority over the former two genera. Therefore, J. P. M. Brenan’s (1953) subsequent merging of Ludwigia under Jussiaea is not acceptable (vide Shenzhen Code Art. 11.5). Hara (1953) referenced both Baillon and Brenan, and followed the then-practiced botanical code to accept Ludwigia over Jussiaea. Hara, and later Raven, made most of the new combinations needed in Ludwigia, and their works firmly established Ludwigia. Raven subdivided the genus into 17 sections using a combination of characters: sepal number, stamens as many or two times as many as sepals; pollen as monads or in tetrads (polyads were not distinguished until reported by J. Praglowski et al. 1983), capsule morphology, and seed morphology. The large sect. Myrtocarpus, primarily distributed in South America, was later subdivided into a total of eight sections (Ramamoorthy 1979; Ramamoorthy and Zardini; Zardini and Raven). Wagner et al. placed sect. Oocarpon into sect. Oligospermum (= sect. Jussiaea), and the present treatment, based on recent molecular analysis (Liu S. H. et al. 2017), combines formerly recognized sect. Microcarpium with sect. Isnardia. This reduces the number of sections to 22, 14 of which are monospecific; Liu et al. did not have sufficient resolution to evaluate classification of sect. Myrtocarpus and its segregates.</p><!-- --><p>Since the synopsis by P. H. Raven ([1963]1964), data have become available for Ludwigia from cytology (M. Kurabayashi et al. 1962; Raven and W. Tai 1979; E. Zardini et al. 1991), palynology (J. J. Skvarla et al. 1975, 1976, 1978; J. Praglowski et al. 1983; V. C. Patel et al. 1984), embryology (H. Tobe and Raven 1983, 1985, 1986, 1986b, 1996), and anatomy (S. Carlquist 1975, 1977, 1982b; R. H. Eyde 1977, 1979, 1981, 1982; R. C. Keating 1982), as well as several published and unpublished revisions of sections. These data provide a rich source of potential characters for phylogenetic analysis. All recent analyses, whether morphological or molecular (see especially Eyde 1977, 1979; R. A. Levin et al. 2003, 2004; Liu S. H.et al. 2017), strongly support Ludwigia as monophyletic and sister to the rest of the family. Liu et al. also found strong support for a monophyletic sect. Ludwigia, a monophyletic sect. Isnardia that includes sect. Microcarpium, and a clade comprised of sects. Isnardia, Ludwigia, and Miquelia that is sister to the rest of the genus. Liu et al. found poor resolution in that second branch, due in part to inadequate sampling, but strong support for monophyletic sects. Jussiaea and Macrocarpon.</p><!-- --><p>Ludwigia appears to have diverged from the common ancestor of the family between 80 and 93 Ma (E. Conti et al. 1997; K. J. Sytsma et al. 2004). The genus exhibits a complex biogeographic pattern, with ten sections endemic or centered in South America (39 species), two in North America (24 species), five in Africa (seven species), two in Asia (two species), and two not clearly centered in a single continent (10 species). Ludwigia has a base chromosome number of x = 8; aneuploidy is unknown, but polyploidy is extensive (P. H. Raven and W. Tai 1979; E. Zardini et al. 1991). S. A. Graham and T. B. Cavalcanti (2001) proposed that x = 8 is the base chromosome number for Lythraceae, which is sister to Onagraceae. This suggests that x = 8 in Ludwigia is a plesiomorphy for Onagraceae, and that the chromosome number changed to x = 11 or x = 10 (in Hauya) on the branch leading to the rest of the family.</p><!-- --><p>In the absence of a more thorough revision and formal phylogenetic analysis of Ludwigia, this treatment follows the most recent classification of the genus by W. L. Wagner et al. (2007), which is based primarily on P. H. Raven ([1963]1964) and supported by subsequent systematic and anatomical studies (especially Raven and W. Tai 1979; J. Praglowski et al. 1983; T. P. Ramamoorthy and E. Zardini 1987; Zardini and Raven 1992). Molecular analyses by Liu S. H. et al. (2017) support inclusion of sect. Microcarpium within sect. Isnardia, which involves more than half of the North American species. The sections are arranged using characters from Raven and elsewhere, as described in Wagner et al.</p><!-- --><p>Species of Ludwigia characteristically grow in wet habitats, and some are nearly or fully aquatic. Those species often have adaptations for growing in water: aerenchyma—respiratory tissue with particularly large intercellular spaces—in the proximal stems, and/or pneumatophores, which are spongy, white roots arising from internodes on floating stems that facilitate aeration needed for root respiration in hydrophytic plants. Species in sect. Ludwigia have fusiform, tuberous roots that may also serve an adaptive function in wet habitats.</p><!-- --><p>Seventy-five species of Ludwigia are self-compatible and seven (in sects. Macrocarpon and Myrtocarpus) are self-incompatible (P. H. Raven 1979). Flowers of Ludwigia are diurnal, remaining open for several days or, sometimes, for only one day (in small-flowered autogamous species); species may be outcrossing and pollinated by bees, flower-flies, or butterflies, or autogamous (Raven).</p><!-- --><p>Several species of Ludwigia are cultivated as aquarium plants (for example, L. repens); others are grown in water gardens. Several species, especially in sect. Jussiaea, are considered noxious, invasive species (M. Wood 2006).</p> |tables= |references= }}<!-- --><div class="treatment-key"> ==Key== <div class="treatment-key-group"> {| class="wikitable fna-keytable" |-id=key-0-1 |1 |Stamens 2 times as many as sepals, in 2 series; seeds in 1 row per locule and embedded in endocarp, or 2 to several rows and free. |[[#key-0-2| > 2]] |-id=key-0-2 |2 |Seeds in 1 row per locule, embedded in segment of endocarp, with inconspicuous raphe; capsules cylindric, subcylindric, or subclavate, terete, subterete, or obscurely angled. |[[#key-0-3| > 3]] |-id=key-0-3 |3 |Stems usually erect or ascending, rarely floating or creeping; seeds loosely embedded in horseshoe-shaped segment of endocarp, easily detached; pollen in polyads; leaves alternate [. |[[Ludwigia sect. Seminudae] 6. Ludwigia leptocarpa|Ludwigia sect. Seminudae] 6. Ludwigia leptocarpa]] |-id=key-0-3 |3 |Stems floating or creeping and ascending to erect; seeds firmly embedded in woody segment of endocarp; pollen as monads; leaves alternate or fascicled [. |[[Ludwigia sect. Jussiaea].|Ludwigia sect. Jussiaea].]] |-id=key-0-4 |4 |Bracteoles deltate, 0.5–1 × 0.5–1 mm; leaf blades mostly oblong or elliptic, petioles 0.3–6 cm; capsules 10–14 mm, pedicels 7–60(–90) mm; seeds 1–1.5 × 0.9–1.3 mm; sepals 3–12 mm. |[[Ludwigia peploides|Ludwigia peploides]] |-id=key-0-4 |4 |Bracteoles narrowly or broadly obovate, 1–1.8 × 0.7–0.8 mm; leaf blades mostly lanceolate or oblanceolate, petioles 0.1–2(–2.5) cm; capsules (11–)14–25(–30) mm, pedicels (9–)13–25(–85) mm; seeds 0.8–1 × 0.8–1 mm; sepals 6–19 mm. |[[#key-0-5| > 5]] |-id=key-0-5 |5 |Emergent plant sparsely to densely villous; petioles 0.5–2(–2.5) cm; sepals (8–)12–19 mm; petals (15–)20–30 mm. |[[Ludwigia hexapetala|Ludwigia hexapetala]] |-id=key-0-5 |5 |Emergent plant generally villous and viscid; petioles 0.1–1.1 cm; sepals 6–12(–16) mm; petals (12–)16–20(–26) mm. |[[Ludwigia grandiflora|Ludwigia grandiflora]] |-id=key-0-2 |2 |Seeds in several rows per locule, free, raphe enlarged or inconspicuous; capsules obconic, obpyramidal, or cylindric, angled, winged, or terete. |[[#key-0-6| > 6]] |-id=key-0-6 |6 |Seeds with enlarged raphe ± equal to seed body; capsules cylindric to clavate, subterete to ± angled; sepals 4 [. |[[Ludwigia sect. Macrocarpon].|Ludwigia sect. Macrocarpon].]] |-id=key-0-7 |7 |Stems 60–250(–400) cm; sepals (6–)8–13 × 3–7 mm; petals (5–)10–20 × 5–20 mm; capsules (17–50 mm) usually exceeding pedicels (5–25 mm). |[[Ludwigia octovalvis|Ludwigia octovalvis]] |-id=key-0-7 |7 |Stems 20–120 cm; sepals 10–20 × 7–12 mm; petals 20–35 × 10–30 mm; capsules (20–35 mm) rarely exceeding pedicels (10–40 mm). |[[Ludwigia bonariensis|Ludwigia bonariensis]] |-id=key-0-6 |6 |Seeds with inconspicuous raphe; capsules obconic or obpyramidal, oblong-obovoid, or subclavate to squarish cylindric, 4+-angled; sepals 4 or 5[–7]. |[[#key-0-8| > 8]] |-id=key-0-8 |8 |Stems terete or angled; capsules ± 4- or 5-angled; plants perennial herbs or shrubs, usually pubescent, rarely glabrous [. |[[Ludwigia sect. Myrtocarpus] 1. Ludwigia peruviana|Ludwigia sect. Myrtocarpus] 1. Ludwigia peruviana]] |-id=key-0-8 |8 |Stems strongly 4-angled or -winged; capsules strongly 4+-angled or -winged; plants annual or short-lived perennial herbs, glabrous or sometimes strigillose on leaves and/or inflorescences [. |[[Ludwigia sect. Pterocaulon].|Ludwigia sect. Pterocaulon].]] |-id=key-0-9 |9 |Leaves sessile; stems sharply 4-angled and -winged; sepals 7–12 × 1.5–4 mm; petals 10–20 × 10–18 mm. |[[Ludwigia decurrens|Ludwigia decurrens]] |-id=key-0-9 |9 |Leaves with petioles 0.2–2.2 cm; stems 4-angled, rarely -winged; sepals 3–6 × 1–2 mm; petals 3.5–5 × 2–2.5 mm. |[[Ludwigia erecta|Ludwigia erecta]] |-id=key-0-1 |1 |Stamens as many as sepals, in 1 series; seeds in several rows per locule, free. |[[#key-0-10| > 10]] |-id=key-0-10 |10 |Stems erect; roots often fusiform, fascicled; capsules globose, subcuboid, or ellipsoid, terete to 4-angled or 4-winged, with hard walls, dehiscing by terminal pore; petals present; leaves alternate [. |[[Ludwigia sect. Ludwigia].|Ludwigia sect. Ludwigia].]] |-id=key-0-11 |11 |Leaves: petioles 0.1–0.3(–0.7) cm, blades attenuate; nectary disc slightly elevated, rounded; pedicels 2–7 mm, shorter than or equaling capsule. |[[Ludwigia alternifolia|Ludwigia alternifolia]] |-id=key-0-11 |11 |Leaves: sessile, blades cuneate to attenuate; nectary disc elevated, domed, (prominently 4-lobed); pedicels 3–17 mm, equal to or exceeding capsule. |[[#key-0-12| > 12]] |-id=key-0-12 |12 |Stems usually densely erect-hirsute, sometimes glabrous, well branched distally; leaf blades lanceolate to ovate-oblong; bracteoles 2.5–7 mm; pedicels 3–10 mm. |[[Ludwigia hirtella|Ludwigia hirtella]] |-id=key-0-12 |12 |Stems strigillose to glabrate, simple or sparsely branched, often near base; leaf blades ovate or obovate proximally, lanceolate-linear or linear distally; bracteoles 0.7–3.2(–5) mm; pedicels 5–17 mm. |[[#key-0-13| > 13]] |-id=key-0-13 |13 |Petals 9–12 mm; style 1.5–3.3 mm, stigma not exserted beyond anthers; capsules 4–7 × 4–5 mm, subcuboid to squarish globose, often 4-winged. |[[Ludwigia maritima|Ludwigia maritima]] |-id=key-0-13 |13 |Petals 14–19 mm; style 5–9.5 mm, stigma as long as or exserted beyond anthers; capsules 2–6.8 × 1.6–3.3 mm, subglobose to ellipsoid, not winged. |[[Ludwigia virgata|Ludwigia virgata]] |-id=key-0-10 |10 |Stems erect, ascending, prostrate, or decumbent; roots not fusiform, often with stolons or rhizomes; capsules subcylindric to clavate, oblong-obovoid, obconic, broadly obpyramidal or subglobose, terete to sharply angled, with hard or thin walls, dehiscent by apical ring or lenticular slits along locule edges or indehiscent; petals present or absent; leaves alternate or opposite [. |[[Ludwigia sect. Isnardia].|Ludwigia sect. Isnardia].]] |-id=key-0-14 |14 |Leaves opposite; stems prostrate or decumbent, erect at tips, sometimes ascending; plants often forming mats, without stolons or rhizomes. |[[#key-0-15| > 15]] |-id=key-0-15 |15 |Petals 0; sepals 1–2 mm; anthers 0.2–0.4 mm; capsules (1.6–)2–5 mm, less than 2 times as long as broad, walls thin; pollen shed as monads. |[[#key-0-16| > 16]] |-id=key-0-16 |16 |Plants nearly glabrous; petioles 0.1–2.5 cm; seeds yellowish brown. |[[Ludwigia palustris|Ludwigia palustris]] |-id=key-0-16 |16 |Plants densely strigillose; petioles 0.3–0.9 cm; seeds dark reddish brown. |[[Ludwigia spathulata|Ludwigia spathulata]] |-id=key-0-15 |15 |Petals 4, sometimes caducous; sepals 1.8–10 mm; anthers 0.4–2 mm; capsules 4–10.5 mm, generally more than 2 times as long as broad, walls hard; pollen usually shed in tetrads, rarely as monads. |[[#key-0-17| > 17]] |-id=key-0-17 |17 |Leaf blades narrowly elliptic to broadly lanceolate-elliptic or suborbiculate; petals 1.1–3 mm; sepals 1.8–5 mm, about as long as wide; mature pedicels 0.1–3 mm. |[[Ludwigia repens|Ludwigia repens]] |-id=key-0-17 |17 |Leaf blades narrowly elliptic to oblanceolate-elliptic or narrowly oblanceolate to linear; petals 4.5–11 mm; sepals (3.5–)4–10 mm, about 2–3 times as long as wide; mature pedicels (4.5–)6–45 mm. |[[#key-0-18| > 18]] |-id=key-0-18 |18 |Petals 7–11 mm; anthers 1.3–2 mm; mature pedicels (12–)17–45 mm, generally much longer than subtending leaves. |[[Ludwigia arcuata|Ludwigia arcuata]] |-id=key-0-18 |18 |Petals 4.5–5.5 mm; anthers 0.7–1 mm; mature pedicels (4.5–)6–15 (–20) mm, as long as or shorter than subtending leaves. |[[Ludwigia brevipes|Ludwigia brevipes]] |-id=key-0-14 |14 |Leaves alternate, rarely opposite proximally; stems erect or ascending, rarely prostrate; plants not forming mats, often with stolons, rarely with rhizomes (in L. suffruticosa). |[[#key-0-19| > 19]] |-id=key-0-19 |19 |Capsules subcylindric to elongate-obpyramidal, 2–10(–12) mm, usually at least 2 times as long as broad. |[[#key-0-20| > 20]] |-id=key-0-20 |20 |Petals 0; sepals 1.1–2.3 mm; stem leaves usually narrowly elliptic to elliptic, rarely sublinear, petioles 0–1.5 cm, blades 3–12 cm. |[[Ludwigia glandulosa|Ludwigia glandulosa]] |-id=key-0-20 |20 |Petals 4; sepals 2.5–7 mm; stem leaves linear to elliptic-linear or linear-oblanceolate, sessile or subsessile, blades 1.5–6(–8.5) cm. |[[#key-0-21| > 21]] |-id=key-0-21 |21 |Capsules subcylindric, irregularly dehiscent; seeds reddish brown; anthers 0.6–1.1 mm. |[[Ludwigia linifolia|Ludwigia linifolia]] |-id=key-0-21 |21 |Capsules elongate-obpyramidal, dehiscent by apical ring; seeds light brown; anthers 1–2 mm. |[[Ludwigia linearis|Ludwigia linearis]] |-id=key-0-19 |19 |Capsules oblong-obovoid, obpyramidal, or obconic to subglobose, (1–)1.5–5(–7) mm, less than 2 times as long as broad. |[[#key-0-22| > 22]] |-id=key-0-22 |22 |Flowers in densely clustered terminal racemes or spikes; stems unbranched or slightly branched; rhizomes often present. |[[Ludwigia suffruticosa|Ludwigia suffruticosa]] |-id=key-0-22 |22 |Flowers in elongate, loose, leafy axillary racemes or spikes; stems usually well branched, sometimes unbranched; rhizomes absent. |[[#key-0-23| > 23]] |-id=key-0-23 |23 |Plants usually densely pubescent throughout. |[[#key-0-24| > 24]] |-id=key-0-24 |24 |Plants densely strigillose; bracteoles 0.5–1.5 mm; mature pedicels 0.5–1.2(–2.3) mm. |[[Ludwigia sphaerocarpa|Ludwigia sphaerocarpa]] |-id=key-0-24 |24 |Plants densely hirtellous; bracteoles (1.5–)2–6.5(–7.2) mm; mature pedicels 0–1 mm. |[[#key-0-25| > 25]] |-id=key-0-25 |25 |Sepals 3.5–5.5(–6) mm, adaxial surface creamy white, tips reflexed; style 1–2 mm; seed surface cells nearly isodiametric. |[[Ludwigia pilosa|Ludwigia pilosa]] |-id=key-0-25 |25 |Sepals 1.5–3 mm, adaxial surface green, tips not reflexed; style 0.3–0.5 mm; seed surface cells transversely elongate. |[[Ludwigia ravenii|Ludwigia ravenii]] |-id=key-0-23 |23 |Plants glabrous or nearly so, sometimes with hairs on raised lines decurrent from leaf axils. |[[#key-0-26| > 26]] |-id=key-0-26 |26 |Capsules obpyramidal, sharply 4-angled and 4-winged, dehiscent by apical ring. |[[#key-0-27| > 27]] |-id=key-0-27 |27 |Stems subterete or slightly ridged; sepals pale green, 1.5–2.5 mm, about 1/2 as long as capsule; capsule wall not bulging; pollen shed in tetrads; seed surface cells nearly isodiametric. |[[Ludwigia lanceolata|Ludwigia lanceolata]] |-id=key-0-27 |27 |Stems slightly to distinctly winged; sepals creamy white adaxially, 2–4 mm, about as long as capsule; capsule wall somewhat bulging; pollen shed as monads; seed surface cells transversely elongate. |[[Ludwigia alata|Ludwigia alata]] |-id=key-0-26 |26 |Capsules obconic or oblong-obovoid, with 4 rounded angles or subterete, dehiscent by loculicidal slits, apical ring, or irregularly. |[[#key-0-28| > 28]] |-id=key-0-28 |28 |Nectary disc nearly flat at ovary apex; capsules 1–1.5 mm, thin- walled, dehiscent by apical ring; seeds dark reddish brown. |[[Ludwigia microcarpa|Ludwigia microcarpa]] |-id=key-0-28 |28 |Nectary disc raised 0.3–0.75 mm at ovary apex; capsules 1.5–7 mm, hard-walled, dehiscent irregularly or by loculicidal slits; seeds light brown to brown. |[[#key-0-29| > 29]] |-id=key-0-29 |29 |Leaf blades elliptic, lanceolate, oblong-elliptic to very narrowly so; stolons present; capsules irregularly dehiscent; pollen shed in tetrads. |[[#key-0-30| > 30]] |-id=key-0-30 |30 |Bracteoles 3.5–6.5(–8) mm; sepals pale green, apex elongate-acuminate, spreading or reflexed; capsules 4–7 mm, oblong-obovoid, pedicels 0.1–0.3 mm. |[[Ludwigia polycarpa|Ludwigia polycarpa]] |-id=key-0-30 |30 |Bracteoles 0.5–1.5 mm; sepals yellow or cream adaxially, apex acuminate, ascending; capsules 2–4(–4.5) mm, subglobose, pedicels 0.5–1.2(–2.3) mm. |[[Ludwigia sphaerocarpa|Ludwigia sphaerocarpa]] |-id=key-0-29 |29 |Leaf blades spatulate to oblanceolate to very narrowly so; stolons rarely present; capsules dehiscent by loculicidal slits; pollen shed as monads. |[[#key-0-31| > 31]] |-id=key-0-31 |31 |Capsules 1.5–2.5 mm; sepals 1.2–1.8 mm; vestigial petals 0 or very rare; basal leaves sometimes opposite. |[[Ludwigia simpsonii|Ludwigia simpsonii]] |-id=key-0-31 |31 |Capsules (2–)2.5–4(–4.7) mm; sepals 1.5–3 mm; 1–3 vestigial petals sometimes present; all leaves alternate. |[[Ludwigia curtissii|Ludwigia curtissii]] |} </div></div><!-- -->{{#Taxon: name=Ludwigia |author=Peter C. Hoch |authority=Linnaeus |rank=genus |parent rank=subfamily |synonyms= |basionyms= |family=Onagraceae |distribution=North America;Mexico;West Indies;Bermuda;Central America;South America;se Asia;Africa;Indian Ocean Islands;Pacific Islands;in Europe;w;s Asia;Australia |reference=None |publication title=Sp. Pl. |publication year= |special status= |source xml= |subfamily=Onagraceae subfam. Ludwigioideae |genus=Ludwigia |aerenchymum texture=spongy |anther dehiscence=3(-5)-aperturate |anther fixation=versatile |apex shape=valvelike;conical;flat |base position relational=surrounding |base presence=absent |blade shape=deltate;usually linear;lanceolate oblong or obovate |blade size=reduced |bracteole coloration=dark red;black |bracteole duration=deciduous |bracteole prominence=conspicuous |bracteole quantity=2 |bracteole shape=scalelike |capsule course=straight;slightly curved |capsule dehiscence=dehiscent |capsule orientation=spreading;erect |capsule shape=cylindric;clavate turbinate obpyramidal or globose |flap architecture=long-pedicellate;subsessile |flap arrangement=separating |floral-tube presence=absent |flower architecture=sessile;pedicellate;actinomorphic |flower reproduction=bisexual |fruit course=straight;slightly curved |fruit dehiscence=by a terminal pore;dehiscent |fruit orientation=spreading;erect |fruit shape=cylindric;clavate turbinate obpyramidal or globose |herb architecture=caulescent |herb duration=annual;perennial |herb pubescence=glandular-puberulent;hirtellous;villous;hirtellous;villous;strigillose |leaf arrangement=opposite;alternate |leaf position=cauline |locule quantity=many |margin architecture or shape=entire;glandular-serrulate;serrulate;entire |nectary lobe prominence=raised |nectary lobe shape=depressed |part architecture=branched |part location=submerged |part shape=swollen |petal atypical quantity=5;7 |petal coloration=white;yellow |petal duration=caducous |petal presence=absent |petal quantity=5;4 |pneumatophore coloration=white |pneumatophore shape=inflated |pneumatophore texture=spongy |pollen fixation=basifixed |polyad arrangement=singly |raceme arrangement=paired;solitary;cluster |raceme orientation=ascending;decumbent;erect |raphe prominence=inconspicuous |raphe quantity=8 |raphe size=expanded |raphe variability=equal |row quantity=1;several |seed fusion=free |seed quantity=50;400 |seed relief=pitted;smooth |seed shape=ovoid |sepal coloration=flushed with red;cream;yellow |sepal duration=persistent |sepal life cycle=post-anthesis;post-anthesis |sepal orientation=spreading;suberect |series quantity=2;1 |series size=unequal;subequal |series size or quantity=2 times as many as sepals |stem architecture=rooting |stem growth form or location=floating |stem orientation=pros;erect;spreading |stigma position or shape=distal |stigma quantity=1/2 |stigma shape=hemispherical;capitate;lobed;entire;hemispherical;capitate;lobed;entire |stipule architecture=sessile;petiolate |stipule coloration=green;dark reddish;green |stipule duration=deciduous |stipule presence=absent |style presence=absent |style pubescence=glabrous |submarginal vein prominence=conspicuous |submarginal vein quantity=1 |surface condition=wet |surface relief=papillate |tetrad arrangement=singly }}<!-- -->[[Category:Treatment]][[Category:Onagraceae subfam. 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