Onagraceae
Epilobium
evening-primrose family
spike-primrose, willow-herb, willow-weed
erect to decumbent or prostrate.
erect to ascending or decumbent, simple to well-branched distally or sometimes from base, in some species proximal epidermis exfoliating, strigillose, glandular-puberulent, villous, often mixed, or glabrous, often with raised hairy lines decurrent from leaf axils.
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.
cauline, sometimes also basal, opposite and decussate proximal to inflorescence or only in proximal pairs, or rarely throughout, alternate or, sometimes, fasciculate distally;
stipules absent;
subsessile to petiolate;
blade margins entire or toothed;
bracts usually reduced distally.
axillary, flowers solitary, leafy spikes, racemes, or panicles.
terminal, usually racemes or spikes, rarely panicles, flowers solitary in leaf axils, erect or ascending, sometimes also flowering from proximal nodes;
bracteoles absent.
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.
bisexual, usually actinomorphic, rarely zygomorphic, buds often erect, sometimes recurved;
floral tube deciduous (with sepals, petals, and stamens) after anthesis, obconic or cylindrical, sometimes with bulbous base, with scales or ring of hairs or raised ring of tissue near mouth inside, nectary at base of tube;
sepals 4, spreading individually, usually green or flushed with red or cream, rarely same color as petals, lanceolate;
petals 4, usually rose-purple to white, rarely cream-yellow or orange-red, usually obcordate or broadly obovate, emarginate;
stamens 8, in 2 unequal series with episepalous longer or rarely subequal, erect, anthers versatile, on smallest flowers appearing basifixed, pollen usually shed in tetrads, rarely singly;
ovary 4-locular, style erect, stigma entire and clavate to capitate, or deeply 4-lobed, commissural, receptive only on inner surfaces, surface dry with multicellular papillae.
a loculicidal capsule or indehiscent berry or nutlike.
a capsule, straight or slightly curved, narrowly cylindrical to fusiform or rarely narrowly ellipsoidal, usually terete, rarely ± 4-angled, loculicidally dehiscent, usually splitting to base with intact central column, rarely splitting only on distal 1/3 with central column disintegrating;
pedicellate or sessile.
smooth or sculptured, sometimes with a coma or wings, with straight, oily embryo, 4-nucleate embryo sac, endosperm absent.
usually numerous (1–100+ per locule), usually in 1, rarely 2, rows per locule, very rarely 1 row per capsule by dissolution of septa and central column, surface papillose to finely reticulate or longitudinally ridged, sometimes constricted near micropylar end, rarely with inflated rim around body of seed on adaxial side, with persistent coma at chalazal end or coma absent.
Onagraceae
Epilobium
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.)
Species ca. 165 (41 in the flora).
Epilobium is the largest genus in Onagraceae, distributed mainly in cool temperate, montane, boreal, and arctic areas on all continents except Antarctica. P. H. Raven (1976) proposed many elements of the current classification of Epilobieae, recognizing six sections in Epilobium, including for the first time the genus Zauschneria as a separate section, based on patterns of variation in chromosome number (H. Lewis and Raven 1961; M. Kurabayashi et al. 1962), wood anatomy (S. Carlquist 1975), seed morphology (S. R. Seavey et al. 1977), and pollen wall (J. J. Skvarla et al. 1976) and viscin thread morphology (Skvarla et al. 1978). Raven excluded Boisduvalia from Epilobium, though it later was included (P. C. Hoch and Raven 1992) as two distinct sections, and Raven included Chamaenerion as a section, which was later excluded (Hoch and Raven 1999; W. L. Wagner et al. 2007). Both of these changes from the 1976 classification were based in large part on relationships supported by molecular data (D. A. Baum et al. 1994). The monophyly of this re-defined Epilobium was very strongly supported in analyses of ITS alone (Baum et al.) and ITS plus trnL-F (R. A. Levin et al. 2004), as was the segregation of Chamaenerion from Epilobium. In addition, both analyses strongly supported a clade that includes the former segregated genera Boisduvalia and Zauschneria as well as the sections of Epilobium with chromosome numbers other than n = 18. As treated here, Epilobium is divided into eight sections, one of which has two subsections (Wagner et al.).
The phylogeny of Epilobium as elucidated by D. A. Baum et al. (1994) and later R. A. Levin et al. (2004) suggests complex chromosomal evolution in the genus. Since the outgroup (Chamaenerion) and one major clade (sect. Epilobium) share the base number x = 18, the derivation of the diverse other gametic numbers (n = 9, 10, 12, 13, 15, 16, and 19) appears to have involved aneuploid reduction from x = 18. One explanation of the relationships proposed by the molecular data suggests the early evolution of a lineage with n = 15 (sects. Cordylophorum, Epilobiopsis, and Zauschneria), from which arose a branch with n = 12 (sect. Xerolobium), a separate branch with n = 13 and n = 16 (sect. Crossostigma), and a third branch with n = 9, 10, and 19 (sect. Pachydium). This hypothesis requires the fewest aneuploidy changes, but confirming it will require additional molecular and cytological analysis.
Almost all Epilobium species tested are self-compatible, but at least E. obcordatum is apparently self-incompatible (S. R. Seavey and S. K. Carter 1994, 1996). All species have hermaphroditic, diurnal flowers that usually remain open for more than one day. Many species are modally autogamous, a few primarily cleistogamous, but others, including 15 species in North America, are partly or wholly outcrossing. In the latter group, flowers are often markedly protandrous, with a 4-lobed stigma exserted beyond anthers. Primary pollinators include bees, flower flies, butterflies, moths, and sometimes hummingbirds (sect. Zauschneria). In general, flowering commences in the first year of growth.
Only the nine species (eight in the flora area) of sects. Pachydium, Crossostigma, Epilobiopsis, and Xerolobium are annuals; all other taxa of Epilobium (sects. Cordylophorum, Epilobium, Macrocarpa, and Zauschneria) are perennials. Annual species have taproots and proximal stems usually with peeling epidermis. Perennial species of Epilobium, which have more fibrous root systems and rarely peeling epidermis, vary greatly in the habit and stature, degree of clumping, degree of branching, and mode of perennation.
The various types of perennating structures in Epilobium (R. C. Keating et al. 1982; Chen C. J. et al. 1992) are extremely useful for identification of many taxa; unfortunately, many plants are collected without the structures. Unless care is taken to dig up the bases of the plants, some of the most useful diagnostic features such as turions are lost, making identification more difficult. Perennating structures are less useful for phylogenetic analysis due to the difficulty in determining whether the common possession of a particular type represents an analogous or homologous pattern. However, one type of structure (soboles) is found in at least some taxa of all perennial sections and may be the most generalized type in the genus.
Soboles are here defined as simple, scaly, underground shoots with somewhat elongated internodes and arising from the caudex. Soboles generally give rise to more or less clumped plants with ascending stems. In certain species, including Epilobium rigidum (sect. Macrocarpa), all taxa of sects. Cordylophorum and Zauschneria, and some in sect. Epilobium, soboles arise from more or less woody caudices, a character state that may be plesiomorphic in the genus; all other types of perennating structures are found only in sect. Epilobium and are discussed there.
In addition to habit and perennating structures, certain other morphological features particularly useful for diagnosing plants include: leaf size, shape, attachment, and arrangement on stem; seed surface (papillose, reticulate, or ridged), size, and shape (S. R. Seavey et al. 1977); pubescence type (mainly strigillose: short incurved hairs; villous: long, thin, spreading hairs; and/or glandular-puberulent) and pattern on stem (all around or restricted to raised lines decurrent from base of petioles) and leaves; and some floral features including size, shape, and color. In fact, floral features are diagnostic for only certain sections or species; most species have very similar flowers.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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 |
1. Herbs annual, with taproot, stem epidermis peeling proximally; leaves opposite in proximal pairs, alternate or fasciculate distally. | → 2 |
2. Seed coma usually present, very rarely absent, often easily or readily detached. | → 3 |
3. Herbs 15–200 cm; floral tubes 1–16 mm, sepals 1–8.5 mm, petals 1.5–15(–20) mm; seeds 1.5–2.7 mm; pollen usually shed singly, rarely in tetrads [5b. Epilobium sect. Xerolobium]. | E. brachycarpum |
3. Herbs 5–45 cm; floral tubes 0.4–1.5 mm, sepals 0.5–2.5 mm, petals 1.4–5 mm; seeds 0.6–1.2 mm; pollen shed in tetrads [5c. Epilobium sect. Crossostigma]. | → 4 |
4. Leaves usually folded along midrib, often fasciculate distally; inflorescences congested; petals 1.4–2.5 mm; seeds 0.6–0.9 mm, surface papillose. | E. foliosum |
4. Leaves flat, not fasciculate; inflorescences not congested; petals 2–5 mm; seeds 0.9–1.2 mm, surface reticulate. | E. minutum |
2. Seed coma absent. | → 5 |
5. Capsule walls tough, usually splitting only in distal 1/3; seeds in 2 rows per locule; often with decumbent proximal branches; flowers usually cleistogamous [5e. Epilobium sect. Epilobiopsis]. | → 6 |
6. Capsules 8–12 mm, sharply 4-angled; sepals 1.5–3 mm; seeds 1.2–1.5 mm. | E. cleistogamum |
6. Capsules 4.5–8 mm, subterete; sepals 0.7–1.9 mm; seeds 1–1.3 mm. | E. campestre |
5. Capsule walls flexible, splitting to base; seeds in 1 row per locule or compressed to 1 row per capsule; proximal branches ascending, erect, or absent; flowers chasmogamous or cleistogamous [5f. Epilobium sect. Pachydium]. | → 7 |
7. Capsules with beak 0–0.5 mm, septifragal, septa adherent to intact central axis; bracts wider than cauline leaves. | E. densiflorum |
7. Capsules with beak 2–5 mm, loculicidal, septa adhering to valves, central axis disintegrating; bracts not wider than cauline leaves. | → 8 |
8. Floral tubes 1.5–3 mm, sepals (1.5–)2–6 mm, petals (2.8–)3.5–10 mm; capsules (10–)14–21 mm; seeds in 1 staggered row distally, 1.8–2.3 mm; flowers ± chasmogamous. | E. pallidum |
8. Floral tubes 0.4–1 mm, sepals 0.7–2 mm, petals 1.2–3.2 mm; capsules (6–)8–14 mm; seeds in 4 rows (1 row per locule), 0.9–1.6 mm; flowers ± cleistogamous. | E. torreyi |
1. Herbs perennial, sometimes woody, ± without taproot, stem epidermis usually not peeling, sometimes peeling proximally; leaves usually opposite proximal to inflorescences, alternate distally, not fasciculate. | → 9 |
9. Floral tubes 16–32 mm, bulbous near base, irregular scales at mouth inside; flowers: floral tube, sepals, and petals usually orange-red, very rarely white, slightly zygomorphic, upper petals ± flared at right angle to calyx tube [5g. Epilobium sect. Zauschneria]. | → 10 |
10. Herbs clumped perennials to subshrubs, 10–120 cm; leaves not dimorphic, usually mixed pubescent, rarely glabrate, not white-canescent. | E. canum |
10. Herbs matted perennials, 5–25 cm; leaves dimorphic, proximal ones densely white-canescent and eglandular, distal ones glandular puberulent and scattered villous, not canescent. | E. septentrionale |
9. Floral tubes 0.3–9.5 mm, not or very rarely bulbous near base, scales absent; flowers: floral tube and sepals green or flushed reddish green, petals usually pink, white, or rose-purple, rarely cream, usually actinomorphic, very rarely slightly zygomorphic. | → 11 |
11. Herbs suffrutescent or rhizomatous, rarely herbaceous; proximal stem epidermis usually peeling; stigmas 4-lobed; seeds 1.5–3.4 mm, ± prominently constricted near micropylar end. | → 12 |
12. Leaf blades 20–45 mm, not folded on midrib; sepals 9.5–14.5 mm; petals 16–20 mm; floral tubes 1–1.8 mm [5a. Epilobium sect. Macrocarpa]. | E. rigidum |
12. Leaf blades 9–25 mm, folded on midrib or not; sepals 2.6–6.5 mm; petals 5–9.5 mm; floral tubes 1.8–9.5 mm [5d. Epilobium sect. Cordylophorum]. | → 13 |
13. Leaf blades not folded on midrib; petals cream to light yellow; flowers slightly zygomorphic (upper petals slightly longer, styles declined); sepals 4–6.5 mm; capsules 10–30 mm; seeds 4–8+ seeds per locule; ovaries eglandular. | E. suffruticosum |
13. Leaf blades ± folded on midrib; petals rose-purple; flowers not zygomorphic; sepals 2.6–4.4 mm; capsules 8–16 mm; seeds 1–3 per locule; ovaries glandular pubescent. | → 14 |
14. Leaf blade margins denticulate, surfaces usually glabrescent, rarely strigillose-villous; floral tubes 2.7–3.2(–5) mm; seeds 2.1–2.9 mm. | E. nevadense |
14. Leaf blade margins subentire or low-denticulate, surfaces densely spreading-hairy; floral tubes 5.2–9.5 mm; seeds 1.5–2.4 mm. | E. nivium |
11. Herbs herbaceous or, sometimes, ± suffrutescent; proximal stem epidermis not peeling; stigmas entire or 4-lobed; seeds 0.8–2.2 mm, not constricted near micropylar end [5h. Epilobium sect. Epilobium]. | → 15 |
15. Stigmas 4-lobed, exserted beyond or rarely surrounded by anthers; floral tubes 1–5.5 mm; sepals (2.5–)5–14 mm; petals (4–)8–26 mm. | → 16 |
16. Petals cream-yellow; seed coma tawny, persistent. | E. luteum |
16. Petals pink to rose-purple; seed coma white, dull white, or dingy, sometimes tawny, ± easily or readily detached. | → 17 |
17. Herbs ± suffrutescent, forming shoots from woody caudex; stems 5–25 cm, clumped to cespitose; floral tubes 2.1–5.5 mm. | → 18 |
18. Herbs ± glabrous and glaucous proximal to inflorescences; leaf blades 6–18(–24) mm; floral tubes 3.2–5.5 mm, slightly raised ring of tissue inside. | E. obcordatum |
18. Herbs pubescent throughout, not glaucous; leaf blades 13–26 mm; floral tubes 2.1–4 mm, prominent raised ring of tissue inside. | E. siskiyouense |
17. Herbs herbaceous, forming basal rosettes, stolons, turions, or soboles; stems (5–)15–120(–250) cm, erect, sometimes clumped; floral tubes 1–3 mm. | → 19 |
19. Stems densely villous, often mixed glandular puberulent proximal to inflorescences, 18–120(–250) cm. | → 20 |
20. Leaves sessile, clasping; sepals 6–12 mm; petals 9–20 mm; herbs with thick stolons sometimes terminating in rosette. | E. hirsutum |
20. Leaves with petioles 1–3 mm proximally, subsessile distally, not clasping; sepals 2.5–6 mm; petals 4–8.5 mm; herbs with short-stalked leafy rosettes. | E. parviflorum |
19. Stems densely strigillose to ± glabrous proximal to inflorescences, not villous, (5–)15–75 cm. | → 21 |
21. Stems densely strigillose proximal to inflorescences; seeds densely papillose; sepals 5–6.5 mm; petals 7.5–10 mm. | E. montanum |
21. Stems ± glabrous and glaucous proximal to inflorescences; seeds ridged; sepals 6–10 mm; petals (6–)10–15 mm. | E. oreganum |
15. Stigmas entire, clavate or capitate, surrounded by or, rarely, exserted beyond anthers; floral tubes 0.3–2.6 mm; sepals 1.1–7.5 mm; petals 1.6–10(–14) mm. | → 22 |
22. Herbs with ± threadlike stolons, with or without terminal turions; stems usually erect from base, rarely ascending. | → 23 |
23. Stolons terminating in fleshy turions; stems (5–)15–95 cm, simple to well branched. | → 24 |
24. Stems densely villous, without raised lines from margins of petioles. | E. densum |
24. Stems strigillose to subglabrous, not villous, sometimes with faint raised strigillose lines from margins of petioles. | → 25 |
25. Leaf blade surfaces strigillose abaxially, subglabrous adaxially, with strigillose margins and veins; inflorescences nodding in bud. | E. palustre |
25. Leaf blade surfaces densely strigillose on both sides; inflorescences erect in bud. | E. leptophyllum |
23. Stolons not terminating in turions; stems 5–30 (–40) cm, usually simple, rarely branched, rarely stems 20–80 cm, well branched. | → 26 |
26. Leaf blades 1.5–10 cm; stems 20–80 cm, well branched, not clumped or matted. | E. obscurum |
26. Leaf blades 0.4–2.1 cm; stems 5–30(–40) cm, not or rarely branched, ± loosely clumped or matted. | → 27 |
27. Stems subglabrous, often matted, 8–30(–40) cm; leaf blades broadly elliptic proximally, narrowly elliptic or lanceolate to sublinear distally. | E. oregonense |
27. Stems densely glandular puberulent, loosely clumped, 5–20 cm; leaf blades broadly obovate to orbiculate proximally to ovate or lanceolate distally. | E. howellii |
22. Herbs with rosettes, turions, fleshy soboles or shoots; stem bases erect or ascending. | → 28 |
28. Herbs with small-leafed epigeous or scaly hypogeous soboles; stems usually ± ascending, rarely erect, ± clumped or matted, rarely with basal scales. | → 29 |
29. Stems 8–75(–85) cm, glabrous and ± glaucous proximal to inflorescences, often without raised lines; leaves subsessile, ± clasping; seeds 0.7–1(–1.3) mm, surfaces densely papillose. | E. glaberrimum |
29. Stems 3–50 cm, subglabrous or strigillose, not glaucous, proximal to inflorescences, with distinct raised strigillose lines decurrent from margins of petioles; leaves subsessile or with petiole 1–12 mm, not clasping; seeds 0.7–2.1 mm, surfaces reticulate to densely papillose. | → 30 |
30. Stems strigillose proximal to inflorescences, densely glandular puberulent distally. | E. smithii |
30. Stems subglabrous with raised strigillose lines proximal to inflorescences, mixed strigillose and glandular puberulent or subglabrous distally. | → 31 |
31. Stems 10–50 cm; leaf blades 1.5–6.2 × 0.7–2.9 cm, margins denticulate; capsules 35–100 mm. | → 32 |
32. Petals usually pink to rose-purple, rarely white; pedicels 5–15(–25) mm in fruit; capsules 35–65 mm; petioles 3–9 mm proximally, to 0 mm distally, not winged; seed surfaces usually papillose, sometimes reticulate. | E. hornemannii |
32. Petals white, rarely red-veined or fading pink; pedicels 15–45 mm in fruit; capsules 50–100 mm; petioles 3–12 mm, often winged; seed surfaces reticulate or, sometimes, barely rugose. | E. lactiflorum |
31. Stems 3–20(–25) cm; leaf blades (0.5–)0.7–2.8 × 0.3–1.6 cm, margins subentire to sparsely denticulate; capsules 17–40(–55) mm. | → 33 |
33. Herbs with thin leafy soboles, no woody rootstock, densely clumped or matted, stems nodding in bud; pedicels 5–35(–68) mm in fruit; seeds 0.7–1.4 mm; stems subglabrous, rarely mixed strigillose and sparsely glandular puberulent distally. | E. anagallidifolium |
33. Herbs with wiry, scaly soboles and extended semi-woody rootstock, clumped, stems ± erect; pedicels 2–21 mm in fruit; seeds (1.3–)1.5–2.1 mm; stems subglabrous proximally, ± densely strigillose and mixed glandular- puberulent distally. | E. clavatum |
28. Herbs usually with leafy rosettes or fleshy hypogeous turions, rarely axillary bulblets; stems ± erect, usually not clumped, usually with dark basal scales. | → 34 |
34. Herbs with basal sessile or, rarely, short-stalked, leafy epigeous rosettes. | → 35 |
35. Stems (2–)5–40(–45) cm, simple; leaf blades 0.8-4.5 cm, margins usually subentire, rarely denticulate, subsessile; inflorescences racemes, nodding in bud. | → 36 |
36. Stems 10–40(–45) cm; leaf blades (1.2–)2–4.5 cm, narrowly oblong to narrowly lanceolate proximally; seed surfaces papillate. | E. davuricum |
36. Stems (2–)5–18 cm; leaf blades 0.8–2.1 cm, obovate to narrowly elliptic proximally; seed surfaces reticulate. | E. arcticum |
35. Stems (3–)10–85(–190) cm, ± branched; leaf blades (1–)3–10(–16) cm, margins denticulate to densely serrulate, subsessile or petiole to 10 mm; inflorescences erect racemes, panicles, or corymbs. | → 37 |
37. Seed coma tawny; seed surfaces papillose; leaf blade margins sharply serrulate, 30–75 teeth per side; petioles 4–10 mm; inflorescences eglandular; petals 2.5–5.5 mm, white. | E. coloratum |
37. Seed coma white or dingy; seed surfaces ridged; leaf blade margins serrulate, (8–)15–40 teeth per side; petioles 0–5(–10) mm; inflorescences usually mixed glandular pubescent; petals 2–14 mm, pink to rose-purple or white. | E. ciliatum |
34. Herbs with fleshy underground turions, rarely also with bulblets in proximal or mid-cauline nodes. | → 38 |
38. Herbs ± eglandular; stems 7–30 cm. | → 39 |
39. Pedicels 5–16 mm; seeds 1.7–2.2 mm, surfaces reticulate to low papillose; stems only with hypogeous turions. | E. mirabile |
39. Pedicels 15–38 mm; seeds 0.8–1.2 mm, surfaces papillose; stems with turions and, usually, bulblets in proximal or mid-cauline nodes. | E. leptocarpum |
38. Herbs mixed glandular puberulent, at least on inflorescences; stems 2–120(–190) cm, usually more than 30 cm. | → 40 |
40. Seed surfaces ridged; stems (3–)10–120(–190) cm; leaf blades (1–)3–12(–16) cm; petals 2–14 mm, white, pink, or rose purple. | E. ciliatum |
40. Seed surfaces papillose or reticulate; stems 2–55(–60) cm; leaf blades 0.5–5.5(–6.5) cm; petals 1.6–5.5(–7) mm, white, fading or rarely pink. | → 41 |
41. Pedicels 8–40 mm; capsules ascending, spreading; leaves not clasping, veins inconspicuous; inflorescences ± nodding in bud. | E. hallianum |
41. Pedicels 0–5 mm; capsules erect, appressed to stem; leaves clasping, veins conspicuous; inflorescences ± erect. | E. saximontanum |
- 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
- Local floras: CA, OR,
WA - Local Web sites: CalFlora, CalPhotos, Flora NW,
IL Wildflowers, 
KS Wildflowers, 
LA Plants, 
MD Biodiversity, 
MI Flora, 
MN Wildflowers, 
MO Plants, PNW Herbaria, Turner Photog. - WildflowerSearch
- iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
