Ludwigia
Onagraceae
false loosestrife, primrose-willow, water purslane, water-primrose
evening-primrose family
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.
erect to decumbent or prostrate.
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.
usually deciduous, usually alternate or opposite, sometimes whorled, simple, usually cauline, sometimes basal and forming rosettes;
stipules present, intrapetiolar, usually caducous, relatively small, or absent (tribes Epilobieae and Onagreae);
sessile or subsessile to petiolate;
blade margins usually entire, toothed, or pinnately lobed, rarely bipinnately lobed.
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.
axillary, flowers solitary, leafy spikes, racemes, or panicles.
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.
usually bisexual, (protandrous in Chamaenerion, Clarkia, Epilobium, [and most species of Lopezia]; protogynous in Circaea and Fuchsia), sometimes unisexual (gynodioecious or dioecious, [subdioecious]), usually actinomorphic, sometimes zygomorphic, (2–)4(–7)-merous;
perianth and androecium epigynous;
sepals persistent after anthesis (in Ludwigia), or all flower parts deciduous after anthesis;
floral tube present or absent in Chamaenerion, Ludwigia, [and most species of Lopezia];
sepals usually green or red, rarely pink or purple, valvate;
petals present, rarely absent, often fading darker with age, imbricate or convolute, sometimes clawed;
nectary present;
stamens 2 times as many as sepals and in 2 series, antisepalous set usually longer, rarely all equal (Chamaenerion), or as many as sepals, [in Lopezia reduced to 2 or 1 plus 1 sterile staminode];
filaments distinct;
anthers usually versatile, sometimes basifixed, dithecal, polysporangiate, with tapetal septa, sometimes also with parenchymatous septa, opening by longitudinal slits, pollen grains united by viscin threads, (2 or)3(–5)-aperturate, shed singly or in tetrads or polyads;
ovary inferior, usually with as many carpels and locules as sepals, rarely 1 or 2 (Circaea and Gayophytum), septa sometimes thin or absent at maturity;
placentation axile or parietal;
style 1, stigma 1, with as many lobes as sepals or clavate to globose, papillate or not, and wet with free-running secretions to dry without the secretions;
ovules 1 to numerous per locule, in 1 or several rows or clustered, anatropous, bitegmic.
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.
a loculicidal capsule or indehiscent berry or nutlike.
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].
smooth or sculptured, sometimes with a coma or wings, with straight, oily embryo, 4-nucleate embryo sac, endosperm absent.
Ludwigia
Onagraceae
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.)
Genera 22, species 664 (17 genera, 277 species in the flora).
Members of the Onagraceae are especially richly represented in North America. The family comprises annual and perennial herbs, with some shrubs and a few small to medium-sized trees. Most species occur in open habitats, ranging from dry to wet, with a few species of Ludwigia aquatic, from the tropics to the deserts of western North America, temperate forests, and arctic tundra; some species of Epilobium, Ludwigia, and Oenothera can be weeds in disturbed habitats. Members of the family are characterized by 4-merous flowers (sometimes 2-, 5-, or 7-merous), an inferior ovary, a floral tube in most species, stamens usually two times as many as sepals, and pollen connected by viscin threads. Flowers are usually bisexual, sometimes unisexual, and plants are gynodioecious, matinal, diurnal, or vespertine, self-compatible or self-incompatible, often outcrossing and then pollinated by a wide variety of insects or birds, or autogamous (P. H. Raven 1979; W. L. Wagner et al. 2007).
Onagraceae are known in considerable systematic detail, and information is available on comparative breeding systems and pollination biology, on chromosome numbers and cytogenetic relations, often involving translocations, and on vegetative, floral, and seed anatomy, palynology, and embryology. The phylogeny of the family is known in reasonably good detail, with most parts of the trees generally well-supported.
The suprageneric and generic classification presented by W. L. Wagner et al. (2007) differs in a number of ways from the previous classification (P. H. Raven 1979, 1988). Onagraceae are divided into two subfamilies based on a fundamental basal split recognized in all phylogenetic studies (R. H. Eyde 1981; P. C. Hoch et al. 1993; R. A. Levin et al. 2003, 2004; V. S. Ford and L. D. Gottlieb 2007), with Ludwigia on one branch (as Ludwigioideae), and the rest of the family on a second branch (as Onagroideae). Onagroideae are subdivided into six tribes: Circaeeae (including Fuchsieae), Epilobieae, Gongylocarpeae, Hauyeae, Lopezieae, and Onagreae. The Epilobieae and Onagreae are diverse; together they constitute fully two-thirds of the species in the family and include 15 of the 22 genera. The classification following Wagner et al. can be viewed on the Onagraceae web site by Wagner and Hoch at http://botany.si.edu/Onagraceae.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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. | → 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. | → 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 [1d. Ludwigia sect. Seminudae]. | L. leptocarpa |
3. Stems floating or creeping and ascending to erect; seeds firmly embedded in woody segment of endocarp; pollen as monads; leaves alternate or fascicled [1e. Ludwigia sect. Jussiaea]. | → 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. | L. peploides |
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. | → 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. | L. hexapetala |
5. Emergent plant generally villous and viscid; petioles 0.1–1.1 cm; sepals 6–12(–16) mm; petals (12–)16–20(–26) mm. | L. grandiflora |
2. Seeds in several rows per locule, free, raphe enlarged or inconspicuous; capsules obconic, obpyramidal, or cylindric, angled, winged, or terete. | → 6 |
6. Seeds with enlarged raphe ± equal to seed body; capsules cylindric to clavate, subterete to ± angled; sepals 4 [1c. Ludwigia sect. Macrocarpon]. | → 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). | L. octovalvis |
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). | L. bonariensis |
6. Seeds with inconspicuous raphe; capsules obconic or obpyramidal, oblong-obovoid, or subclavate to squarish cylindric, 4+-angled; sepals 4 or 5[–7]. | → 8 |
8. Stems terete or angled; capsules ± 4- or 5-angled; plants perennial herbs or shrubs, usually pubescent, rarely glabrous [1a. Ludwigia sect. Myrtocarpus]. | L. peruviana |
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 [1b. Ludwigia sect. Pterocaulon]. | → 9 |
9. Leaves sessile; stems sharply 4-angled and -winged; sepals 7–12 × 1.5–4 mm; petals 10–20 × 10–18 mm. | L. decurrens |
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. | L. erecta |
1. Stamens as many as sepals, in 1 series; seeds in several rows per locule, free. | → 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 [1f. Ludwigia sect. Ludwigia]. | → 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. | L. alternifolia |
11. Leaves: sessile, blades cuneate to attenuate; nectary disc elevated, domed, (prominently 4-lobed); pedicels 3–17 mm, equal to or exceeding capsule. | → 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. | L. hirtella |
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. | → 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. | L. maritima |
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. | L. virgata |
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 [1g. Ludwigia sect. Isnardia]. | → 14 |
14. Leaves opposite; stems prostrate or decumbent, erect at tips, sometimes ascending; plants often forming mats, without stolons or rhizomes. | → 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. | → 16 |
16. Plants nearly glabrous; petioles 0.1–2.5 cm; seeds yellowish brown. | L. palustris |
16. Plants densely strigillose; petioles 0.3–0.9 cm; seeds dark reddish brown. | L. spathulata |
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. | → 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. | L. repens |
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. | → 18 |
18. Petals 7–11 mm; anthers 1.3–2 mm; mature pedicels (12–)17–45 mm, generally much longer than subtending leaves. | L. arcuata |
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. | L. brevipes |
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). | → 19 |
19. Capsules subcylindric to elongate-obpyramidal, 2–10(–12) mm, usually at least 2 times as long as broad. | → 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. | L. glandulosa |
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. | → 21 |
21. Capsules subcylindric, irregularly dehiscent; seeds reddish brown; anthers 0.6–1.1 mm. | L. linifolia |
21. Capsules elongate-obpyramidal, dehiscent by apical ring; seeds light brown; anthers 1–2 mm. | L. linearis |
19. Capsules oblong-obovoid, obpyramidal, or obconic to subglobose, (1–)1.5–5(–7) mm, less than 2 times as long as broad. | → 22 |
22. Flowers in densely clustered terminal racemes or spikes; stems unbranched or slightly branched; rhizomes often present. | L. suffruticosa |
22. Flowers in elongate, loose, leafy axillary racemes or spikes; stems usually well branched, sometimes unbranched; rhizomes absent. | → 23 |
23. Plants usually densely pubescent throughout. | → 24 |
24. Plants densely strigillose; bracteoles 0.5–1.5 mm; mature pedicels 0.5–1.2(–2.3) mm. | L. sphaerocarpa |
24. Plants densely hirtellous; bracteoles (1.5–)2–6.5(–7.2) mm; mature pedicels 0–1 mm. | → 25 |
25. Sepals 3.5–5.5(–6) mm, adaxial surface creamy white, tips reflexed; style 1–2 mm; seed surface cells nearly isodiametric. | L. pilosa |
25. Sepals 1.5–3 mm, adaxial surface green, tips not reflexed; style 0.3–0.5 mm; seed surface cells transversely elongate. | L. ravenii |
23. Plants glabrous or nearly so, sometimes with hairs on raised lines decurrent from leaf axils. | → 26 |
26. Capsules obpyramidal, sharply 4-angled and 4-winged, dehiscent by apical ring. | → 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. | L. lanceolata |
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. | L. alata |
26. Capsules obconic or oblong-obovoid, with 4 rounded angles or subterete, dehiscent by loculicidal slits, apical ring, or irregularly. | → 28 |
28. Nectary disc nearly flat at ovary apex; capsules 1–1.5 mm, thin- walled, dehiscent by apical ring; seeds dark reddish brown. | L. microcarpa |
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. | → 29 |
29. Leaf blades elliptic, lanceolate, oblong-elliptic to very narrowly so; stolons present; capsules irregularly dehiscent; pollen shed in tetrads. | → 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. | L. polycarpa |
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. | L. sphaerocarpa |
29. Leaf blades spatulate to oblanceolate to very narrowly so; stolons rarely present; capsules dehiscent by loculicidal slits; pollen shed as monads. | → 31 |
31. Capsules 1.5–2.5 mm; sepals 1.2–1.8 mm; vestigial petals 0 or very rare; basal leaves sometimes opposite. | L. simpsonii |
31. Capsules (2–)2.5–4(–4.7) mm; sepals 1.5–3 mm; 1–3 vestigial petals sometimes present; all leaves alternate. | L. curtissii |
1. Sepals persistent or tardily caducous after anthesis; flowers (3 or)4 or 5(–7)-merous; floral tube absent; petals yellow or white [a. Onagraceae subfam. Ludwigioideae, p. 70]. | Ludwigia |
1. Sepals deciduous after anthesis (along with other flower parts); flowers (2–)4-merous; floral tube usually present, often elongate, if absent then petals usually rose purple or pink, rarely white [b. Onagraceae subfam. Onagroideae, p. 101]. | → 2 |
2. Stipules present and soon deciduous; fruit indehiscent (berry or burlike capsule with hooked hairs) [b1. Onagraceae subfam. Onagroideae tribe Circaeeae, p. 101]. | → 3 |
3. Fruit a berry; seeds few to ca. 500; flowers 4-merous. | Fuchsia |
3. Fruit a capsule, burlike, with stiff, hooked hairs; seeds 1 or 2; flowers 2-merous. | Circaea |
2. Stipules absent; fruit usually a capsule, sometimes indehiscent. | → 4 |
4. Seeds usually comose, coma rarely secondarily lost; sepals erect or spreading; stigmas with dry multicellular papillae, entire or 4-lobed, lobes commissural; x = 18 [b2. Onagraceae subfam. Onagroideae tribe Epilobieae, p. 107]. | → 5 |
5. Floral tube absent; stamens subequal; style deflexed at anthesis, later erect, stamens initially erect, later deflexed; leaves usually alternate, rarely subopposite or subverticillate proximally. | Chamaenerion |
5. Floral tube present; stamens in 2 unequal whorls; style and stamens erect; leaves opposite, at least near base of stem. | Epilobium |
4. Seeds not comose; sepals reflexed; stigmas usually wet, non-papillate, and entire or (3 or)4-lobed (non-commissural), sometimes (Clarkia) lobes commissural and then with dry unicellular papillae; x = 7 [b3. Onagraceae subfam. Onagroideae tribe Onagreae, p. 159]. | → 6 |
6. Stigmas with commissural lobes and dry, unicellular papillae; flowers usually protandrous. | Clarkia |
6. Stigmas hemispherical to subglobose or subcapitate, peltate, or 4-lobed, not commissural, surface wet, non-papillate; flowers not protandrous. | → 7 |
7. Ovaries 2-locular; stems usually delicate. | Gayophytum |
7. Ovaries (3 or)4-locular; stems usually not especially delicate. | → 8 |
8. Seeds with concave and convex sides, concave side with a thick wing, convex side covered with glasslike, clavate hairs; petals white with yellow basal area. | Chylismiella |
8. Seeds not concave/convex and not with a wing and clavate hairs; petals yellow, purple, red, or white, if white, mostly without yellow base. | → 9 |
9. Ovaries with a slender, sterile apical projection; plants usually acaulescent. | → 10 |
10. Herbs perennial; sterile projection of ovary persistent with fertile part in fruit, projection without visible abscission lines at its junctures with floral tube or fertile part of ovary. | Taraxia |
10. Herbs annual; sterile projection of ovary with visible abscission lines at its junctures with both short floral tube and fertile part of ovary. | Tetrapteron |
9. Ovaries without an apical projection; plants usually caulescent, sometimes acaulescent (in Oenothera). | → 11 |
11. Styles with peltate indusium at base of stigma, at least at younger stages prior to anthesis; stigmas (3 or)4-lobed, receptive all around (or peltate to discoid or nearly square in sect. Calylophus). | Oenothera |
11. Styles without indusium; stigmas usually subglobose to globose, subcapitate, capitate, or cylindrical (Eulobus), rarely conical-peltate and ± 4-lobed. | → 12 |
12. Seeds in 2 rows per locule; capsules pedicellate; leaves mostly basal, blades often pinnately lobed, rarely bipinnately, sometimes unlobed, or lateral lobes greatly reduced or absent, terminal lobe usually large, abaxial surface of leaves or leaf margins with conspicuous, usually brown, oil cells. | Chylismia |
12. Seeds in 1 row per locule; capsules usually sessile, rarely very shortly pedicellate; leaves not predominately basal, blades not lobed or pinnatifid, leaves without oil cells. | → 13 |
13. Petals usually white, rarely red or tinged red; flowers vespertine. | Eremothera |
13. Petals yellow, often with red flecks or spots; flowers diurnal. | → 14 |
14. Flowering stems virgate; leaf blades pinnatifid to lobed; petals yellow with red flecks near base; seeds usually with purple spots; floral tube with a lobed disc. | Eulobus |
14. Flowering stems not virgate; leaf blades not pinnatifid, margins entire or toothed; petals yellow, sometimes with 1+ red spots at base; seeds without purple spots; floral tube without a lobed disc. | → 15 |
15. Stems densely leafy distally, nearly leafless proximally, with many slender, ascending branches from base; capsules strongly flattened, straight. | Neoholmgrenia |
15. Stems usually leafy throughout, branched throughout or with a few basal branches; capsules not flattened, subterete or 4-angled, often flexuous or curled, sometimes straight. | → 16 |
16. Capsules subterete; flowers only from distal nodes; seeds appearing smooth, glossy, triangular in cross section. | Camissonia |
16. Capsules 4-angled, at least when dry; flowers from basalmost to distal nodes; seeds dull, flattened. | Camissoniopsis |
- Local floras:
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
- Local floras: CA, OR
- Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria
- WildflowerSearch
- iNaturalist (observations)
- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
