Ludwigia bonariensis |
Ludwigia |
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Carolina primrose-willow |
false loosestrife, primrose-willow, water purslane, water-primrose |
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Habit | Herbs, from woody rootstock. | Herbs, usually perennial, rarely annual, or shrubs, [rarely trees], caulescent, usually glabrous, strigillose, villous, or hirtellous, rarely glandular-puberulent. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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 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. |
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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. |
cauline, usually alternate, rarely opposite; stipules present, often deciduous, usually dark reddish green; usually petiolate, sometimes sessile; 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. |
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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. |
spikes, racemes, or clusters, solitary or paired in leaf axils, erect or decumbent and ascending at tip; bracteoles usually 2 and conspicuous, black or dark red, often scalelike, at or near base of ovary, sometimes deciduous early, rarely absent. |
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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. |
bisexual, actinomorphic, pedicellate or sessile; floral tube absent; 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; petals caducous, usually (3 or)4 or 5(–7), sometimes 0, usually yellow, sometimes white, when yellow, then often ultraviolet-reflecting, margins entire; stamens as many as sepals in 1 series, or 2 times as many as sepals in 2 subequal or unequal series; anthers versatile, on smallest flowers appearing basifixed, pollen shed singly or in polyads or tetrads, 3(–5)-aperturate; 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; style present [very rarely absent in sect. Arborescentes], usually glabrous; stigma entire or irregularly lobed, capitate or hemispherical, distal 1/2 receptive, surface wet and papillate. |
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Fruit | 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. |
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Capsules | clavate-cylindric, subterete to obtusely 4-angled, 20–35 × 3.5–5 mm, thin walls, irregularly dehiscent, tapering to pedicel 10–40 mm. |
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Seeds | in several indistinct rows per locule, yellow-brown, oblong (appearing round), 0.5 mm, shiny, raphe 2/3 as wide as body. |
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]. |
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x |
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2n | = 16. |
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Ludwigia bonariensis |
Ludwigia |
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Phenology | Flowering summer. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Habitat | Wet places, mainly along coastal areas, especially ditches, banks near brackish water. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Elevation | 0–200[–2600] m. (0–700[–8500] ft.) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Distribution |
AL; FL; MS; NC; SC; TX; Mexico (Chihuahua, Durango, Puebla, Quintana Roo, Tabasco, Tamaulipas, Veracruz); South America (Argentina, Bolivia, Brazil, Paraguay, Uruguay)
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North America; Mexico; Central America; South America; West Indies; Bermuda; se Asia; Africa; Indian Ocean Islands; Pacific Islands [Introduced in Europe, w, s Asia, Australia] |
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Discussion | Species 82 (31 in the flora). 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. 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. 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. 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. 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. 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). 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). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 10. | FNA vol. 10. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Parent taxa | Onagraceae > subfam. Ludwigioideae > Ludwigia > sect. Macrocarpon | Onagraceae > subfam. Ludwigioideae | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Sibling taxa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Subordinate taxa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Synonyms | Jussiaea bonariensis, J. neglecta, J. suffruticosa var. bonariensis | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Name authority | (Micheli) H. Hara: J. Jap. Bot. 28: 291. (1953) | Linnaeus: Sp. Pl. 1: 118 — (as Ludvigia), [1204]. 1753: Gen. Pl. ed. 5, 55. (1754) — (as Ludvigia), [1204]. 1753 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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