Saxifragaceae
Micranthes
saxifrage family
saxifrage
appearing in spring, summer, or autumn with leaves usually present (usually appearing in autumn or winter after basal leaves have withered in Jepsonia), leafless, or leafy and bearing 1–5 cauline leaves proximally, glabrous or short to long stipitate-glandular or eglandular, hairs usually multicellular (unicellular in Astilbe, Saxifragopsis).
± erect, leafless, 2–125 cm.
usually in basal rosettes, sometimes cauline, usually alternate, sometimes opposite (Chrysosplenium, Lithophragma, Mitella, Saxifraga), usually simple (compound in Astilbe, sometimes compound in Lithophragma, Tiarella);
stipules absent or present;
petiole absent or present, usually not jointed distally at attachment to blade (jointed distally in Saxifragopsis), usually not peltate (peltate in Darmera), not producing adventitious buds at apices of petioles of basal rosette and cauline leaves (usually producing adventitious buds at apices of petioles in Tolmiea);
blade margins entire, crenate, serrate, or dentate, ciliate or glandular-ciliate.
basal, (proximally cauline and crowded in M. tolmiei);
stipules absent;
petiole present (absent in M. bryophora, M. tolmiei; ± absent in M. foliolosa, M. stellaris; appearing absent in M. tempestiva);
blade obtrullate, spatulate, fan-shaped, or obovate to oblanceolate, linear to oblong, elliptic or rhombic, to lanceolate, ovate, triangular, deltate, round, or reniform, lobed or unlobed, base attenuate or cuneate to truncate or cordate, ultimate margins entire, crenate, serrate, or dentate, (without lime-secreting hydathodes), apex acute to obtuse or rounded;
venation pinnate or palmate.
usually terminal racemes, panicles, cymes (simple or compound), thyrses (with lateral dichasial or monochasial cymose branches), or solitary flowers (Chrysosplenium, Lithophragma), sometimes axillary cymes (Chrysosplenium), usually arising from terminal or axillary buds in rosettes, 2–300(–1000+)-flowered, bracteate or ebracteate.
cymes or thyrses, sometimes solitary flowers, from terminal buds in rosettes, 2–70+[–1000]-flowered, (flowers sometimes replaced by bulbils in M. bryophora, M. ferruginea, M. foliolosa, M. petiolaris, M. stellaris), (scapose), bracteate; (bracts reduced or sometimes leaflike, only proximal in M. tolmiei).
usually bisexual, sometimes unisexual (Astilbe, Saxifraga), homostylous (heterostylous in Jepsonia), usually radially symmetric, sometimes bilaterally symmetric (Bensoniella, Heuchera, Micranthes, [Saxifraga], Tiarella, Tolmiea);
perianth and androecium hypogynous, perigynous, or epigynous;
hypanthium free (Bolandra, Jepsonia) or ± adnate to ovary, usually not split to base (split to base in Tolmiea);
sepals usually (4–)5(–6), distinct;
petals usually (4–)5(–6) or absent, distinct, lobed or unlobed;
nectary disc often encircling ovary distally at junction of ovary and free portion of hypanthium;
stamens (2–)5(–9)10;
anthers usually dehiscent longitudinally, rarely by broad terminal openings (Leptarrhena);
staminodes absent;
pistils 1, sometimes appearing 2–3+ (Micranthes), usually 2-carpellate, rarely 3-carpellate (Astilbe, Lithophragma, Micranthes), carpels connate for full length of ovary to barely connate proximally, equal, rarely unequal (Tiarella);
ovary superior to inferior, 1–2(–3)-locular, ovaries fully connate when 1-locular, proximally connate to varying degrees when 2- and 3-locular (Astilbe, Micranthes);
placentation axile, appearing marginal when ovaries are barely connate, or parietal;
ovules anatropous, usually bitegmic, rarely unitegmic (most Micranthes), crassinucellate;
styles 2–3(–4), distinct or connate (Saxifragopsis);
stigmas 2–3(–4), capitate.
radially symmetric (± bilaterally symmetric in M. ferruginea, M. petiolaris);
hypanthium free from or 1/4–3/4 adnate to ovary, free to 0.5 mm, usually green, rarely purplish;
sepals 5, green, sometimes reddish at tips;
petals 5 (absent or 1–5 in M. apetala, M. subapetala), usually white or cream, sometimes greenish, yellowish, pinkish, pink, purplish, purple, or reddish purple, sometimes purple-margined, sometimes orange-, yellowish green-, or yellow-spotted;
nectary disc present or not;
stamens 10, (distinct);
filaments linear and ± flattened or club-shaped;
pistils 2(–3+), 2(–3)-carpellate, carpels distinct or connate to ca. 1/2 their lengths (rarely more);
ovary superior or ± inferior, sometimes appearing more superior in fruit, 2(–3)-locular;
placentation axile (when connate);
styles 2(–3);
stigmas 2–3.
capsular, sometimes folliclelike (Cascadia, Micranthes), 2–3(–4)-beaked, equally valvate (unequally valvate in Tiarella), dehiscence septicidal between beaks.
folliclelike or 2(–3)-beaked.
5–200, tan, brown, dark brown, black, yellowish brown, reddish brown, or red, rarely winged (Astilbe, Jepsonia, Sullivantia), ellipsoid, fusiform, ovoid, oblong, spheroid, oblong-cylindric, flat, or straight on 1 side, convex on other, rarely prismatic, smooth, wrinkled, ribbed, papillate, pitted, or ridged, tuberculate, warty, spiny, cellular-rugulose, or muricate;
embryo straight;
endosperm oily, copious.
brown, oblong, ellipsoid, or ovoid, longitudinally ribbed (ribs ribbonlike or pectinate).
= 8.
Saxifragaceae
Micranthes
Genera ca. 38, species ca. 600 (23 genera, 158 species in the flora).
Classification of Saxifragaceae has been varied and controversial (e.g., A. Cronquist 1981; H. G. A. Engler 1930; J. Hutchinson 1973; G. K. W. Schulze-Menz 1964b; A. L. Takhtajan 1997; R. F. Thorne 1992). Molecular phylogenetic data (D. R. Morgan and D. E. Soltis 1993; Soltis et al. 1993, 2001; Angiosperm Phylogeny Group 1998, 2003) reveal that genera of Saxifragaceae in the broad sense are allied with at least ten separate, often distantly related families of flowering plants. These data also suggest that Saxifragaceae in the narrow sense as treated here consists of about 38 genera worldwide, equivalent to subfamily Saxifragoideae, one of the 15 subfamilies recognized by Engler and one of the 17 recognized by Schulze-Menz of the broadly defined Saxifragaceae. Molecular phylogenetic data (Soltis et al. 2001) show that the narrowly defined Saxifragaceae fall into two major groups: Saxifraga, and the heucheroid clade encompassing all other genera. Molecular data further show that Saxifraga, as traditionally understood, is polyphyletic, comprising two distinct lineages (treated here as Saxifraga and Micranthes) and the monospecific North American Cascadia. The major split between Saxifraga and the heucheroid clade is supported not only by molecular data from six DNA regions but by differences in patterns of floral morphology. Saxifraga has a relatively uniform floral morphology (radially symmetric flowers, with bilateral symmetry restricted to one Asian group of species, which consistently have the same number of sepals, petals, stamens, and carpels). Almost all of the variation in the family in numbers of sepals, petals, stamens, and carpels occurs in the heucheroid clade. Radially symmetric flowers predominate there, but some bilateral flowers are found in Bensoniella, Micranthes, Tolmiea, and some species of Heuchera.
Penthorum, the only genus in Penthoroideae of Saxifragaceae (H. G. A. Engler 1930), is morphologically anomalous in the Saxifragaceae and has often been included in Crassulaceae or, as treated here, its own family, Penthoraceae (Angiosperm Phylogeny Group 1998). Itea and Ribes, sole members of Iteoideae and Ribesoideae, respectively, are treated here as separate families, Iteaceae and Grossulariaceae. Crassulaceae, Grossulariaceae, Iteaceae, Paeoniaceae, Penthoraceae, and Saxifragaceae belong to the Saxifragales, as treated here, as well as Altingiaceae, Cercidiphyllaceae, Daphniphyllaceae, Haloragaceae (which includes Penthoraceae and Tetracarpaeaceae), Hamamelidaceae, Peridiscaceae, and Pterostemonaceae (Soltis et al. 2005).
Carpenteria, Decumaria, Deutzia, Fendlera, Fendlerella, Hydrangea, Jamesia, Philadelphus, and Whipplea once belonged to Hydrangeoideae of Saxifragaceae (H. G. A. Engler 1930) and are treated in the flora as Hydrangeaceae. Escallonia, the sole genus of Escallonioideae (Engler), is treated in the flora as Escalloniaceae. Molecular, morphological, and chemical data (C. R. Bensel and B. F. Palser 1975, 1975b, 1975c, 1975d; B. A. Bohm et al. 1988; M. L. Haskins and W. J. Hayden 1987; L. Hufford and W. C. Dickison 1992; D. R. Morgan and D. E. Soltis 1993; Soltis and B. A. Bohm 1982; Soltis et al. 1993; Soltis and P. S. Soltis 1997; Angiosperm Phylogeny Group 1998, 2003) indicate that Hydrangeaceae and Escalloniaceae are more likely to be related to the asterids, within which Hydrangeaceae appears to be close to Cornales.
Parnassia and Lepuropetalon have been included in Saxifragaceae as the subfamily Parnassioideae in the past (A. Cronquist 1981; H. G. A. Engler 1930; J. Hutchinson 1973; S. A. Spongberg 1972). Based on molecular, morphological, and chemical data, these genera appear to be only distantly related to other genera of Saxifragaceae and are here moved to Parnassiaceae (C. R. Bensel and B. F. Palser 1975, 1975b, 1975c, 1975d; B. A. Bohm et al. 1986; D. R. Morgan and D. E. Soltis 1993; Soltis et al. 2001; A. L. Takhtajan 1969; R. F. Thorne 1992). Molecular phylogenetic analyses (M. W. Chase et al. 1993; Zhang L. B. and M. P. Simmons 2006) have aligned Parnassiaceae with Celastraceae, either as a sister family or as a basal member of Celastraceae.
Molecular systematic studies have revealed that the approximately 38 remaining genera form a strongly supported clade (D. E. Soltis et al. 1993, 2000; Soltis and P. S. Soltis 1997; S. B. Hoot et al. 1999; V. Savolainen et al. 2000) that corresponds to the Saxifragoideae of Engler and is identical to the family circumscriptions of A. L. Takhtajan (1969, 1997) and R. F. Thorne (1992).
H. G. A. Engler’s (1930) subfamily Saxifragoideae contained one tribe, Saxifrageae, which consisted of four subtribes: Astilbinae, Leptarrheninae, Saxifraginae, and Vahliinae. Vahliinae is now known to be very distantly related to the Saxifragaceae. G. K. W. Schulze-Menz (1964b) elevated three of Engler’s subtribes to tribes: Astilbeae, Leptarrheneae, and Saxifrageae. K. Klopfer (1973) later recognized two large groups, one centered around Heuchera having parietal placentation, another centered around Saxifraga having axile placentation. Recent molecular phylogenetic and systematic studies indicate the presence of six well-marked clades, informally recognized as the Astilbe, Boykinia, Chrysosplenium, Darmera, Heuchera, and Leptarrhena groups (reviewed in Soltis et al. 2001). Relationships within some of these groups (e.g., the Boykinia and Heuchera groups) have also been studied in detail from a phylogenetic standpoint (e.g., Soltis and R. K. Kuzoff 1995; Soltis et al. 1997).
During fruit development in some genera (especially Saxifraga and Lithophragma), partially to mostly inferior ovaries swell to become increasingly superior due to allometric shifts (R. K. Kuzoff et al. 2001). Ovary position in keys and descriptions here refers to flowers during or shortly after anthesis. Reports of variation in ovary position in some genera and species may be due to observations of flowers at different developmental stages. D. E. Soltis et al. (2005) reported that most genera of Saxifragaceae display appendicular epigyny in floral development, which begins with a minute convex floral apex. During or after perianth initiation, the floral apex becomes concave, giving rise to an inferior ovary. Ovaries in Saxifragaceae often appear to be nearly superior or one-half to three-fourths inferior, but with their appendicular epigynous ground plan, they are not truly superior or homologous to superior ovaries. Instead, they are “superior mimics” with “pseudosuperior” ovaries.
Species in some North American genera (particularly Boykinia, Darmera, Heuchera, Micranthes, Saxifraga, Tellima, Tiarella, and Tolmiea) are popular horticultural subjects.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 68–93 (45 in the flora).
The ovules of Micranthes species are unitegminate, except those of M. merkii and M. tolmiei (sect. Merkianae), which are bitegminate. Pollen exine is reticulate. These characters help distinguish Micranthes from Saxifraga (see discussion for differences among the genera).
Some circumboreal species (e.g., Micranthes nelsoniana), which show only slight variation in Europe (D. A. Webb and R. J. Gornall 1989), are more variable in North America.
Molecular phylogenies (D. E. Soltis et al. 2001, and references therein) have shown that Saxifraga in the broad sense is not monophyletic and comprises two main lineages, Saxifraga in the narrow sense and Micranthes, which are not sister to each other (for morphologic differences, see discussion of 23. Saxifraga). We recognize these two as distinct genera, as well as the monospecific Cascadia.
Supernumerary chromosomes have been reported in some species (D. E. Soltis 1983), leading to doubts about the accuracy of some reported chromosome numbers, especially those published before 1950. There is also well-documented and extensive occurrence of polyploidy and dysploidy (sometimes reported as aneuploidy) throughout the genus (P. E. Elvander 1984; D. A. Webb and R. J. Gornall 1989).
The stigmas and styles are typically two (except for three in Micranthes texana); occasional flowers on plants in some species may have three or, rarely, four stigmas and styles. In addition, ovary position in some taxa can change from mostly inferior at flowering to superior in fruit; ovary position is described at the flowering stage.
D. A. Webb and R. J. Gornall (1989) provided much ecological and horticultural information on the few European species of the genus.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaves ternately decompound or 3-pinnately compound, never simple; flowers usually unisexual, sometimes bisexual; inflorescences plumose panicles, relatively large, branched, rarely congested and spikelike. | Astilbe |
1. Leaves usually simple, rarely compound; flowers usually bisexual; inflorescences solitary flowers or racemes, panicles, simple or compound cymes, or thyrses | → 2 |
2. Sepals 4; petals absent; stamens 2-8, usually 4 or 8; hypanthia greenish or yellow-green. | Chrysosplenium |
2. Sepals 5(-6); petals (1-)4-5 or absent; stamens 3, 5(-6), or 10; hypanthia usually green, greenish, white, cream, yellow, yellowish green, pink to red or purple, or pinkish to reddish purple | → 3 |
3. Stamens 3; petals 4; hypanthia ± split to base; adventitious buds usually produced at apices of petioles of basal rosette and cauline leaves, sometimes forming plantlets. | Tolmiea |
3. Stamens usually 5 or 10; petals usually 5 or absent; hypanthia not split to base; adventitious buds and plantlets not present at apices of petioles of basal and cauline leaves | → 4 |
4. Leaves peltate. | Darmera |
4. Leaves not peltate | → 5 |
5. Flowers heterostylous (stamens proximal to stigmas in some plants, distal in others); flowering in autumn(-winter) after basal leaves have withered, rarely flowers and leaves present together. | Jepsonia |
5. Flowers homostylous; flowering in spring, summer, or autumn with leaves usually present | → 6 |
6. Placentation parietal; ovaries 1-locular; inflorescences terminal from axillary buds in rosettes | → 7 |
6. Placentation axile or marginal; ovaries 2-3-locular; inflorescences terminal from terminal buds in rosettes | → 15 |
7. Stamens 10; inflorescences usually racemes or panicles, sometimes solitary flowers | → 8 |
7. Stamens 5(-6); inflorescences racemes or thyrses, sometimes resembling panicles or spikes | → 11 |
8. Styles 3; pistils 3-carpellate; sometimes with bulbils in axils of cauline leaves. | Lithophragma |
8. Styles 2; pistils 2-carpellate; bulbils absent in axils of cauline leaves | → 9 |
9. Capsules unequally valvate; petals unlobed; ovaries superior; leaves simple or 3-foliolate. | Tiarella |
9. Capsules equally valvate; petals lobed; ovaries 1/4-1/2 inferior or nearly superior; leaves simple | → 10 |
10. Petals 5-7-lobed; flowering stems 40-90 cm; hypanthia 4.5-9 mm; styles 1-1.5 mm; cauline leaves 2-3. | Tellima |
10. Petals 9-11(-15)-lobed; flowering stems (2-)8-48 (-60) cm; hypanthia (0.6-)0.8-2.7 mm; styles 0.1-0.6 mm; cauline leaves absent or 1-3. | Mitella |
11. Inflorescences thyrses (with cymose side branches), sometimes diffuse (resembling panicles) or dense (resembling spikes); petals unlobed, sometimes absent. | Heuchera |
11. Inflorescences racemes; petals unlobed or lobed, rarely absent | → 12 |
12. Hypanthia 5-9 mm; ovaries 1/4 inferior; petals 4-7-lobed, rarely ± unlobed; rocky ledges, cliffs, alpine open slopes, talus slopes; British Columbia, Oregon, Washington. | Elmera |
12. Hypanthia 0.6-4 mm; ovaries 1/3 to nearly completely inferior; petals 3-11-lobed or unlobed, sometimes absent; moist sites and fir forests from Alaska, British Columbia, and Yukon to Alberta, California, Colorado, Oregon, South Dakota, and Utah, rocky slopes in the Rocky Mountains | → 13 |
13. Styles 0.1-1.1 mm; petals usually 3-11-lobed, sometimes unlobed; hypanthia 0.6-2.7 mm; moist sites; Alaska to South Dakota, Utah, Colorado, California. | Mitella |
13. Styles absent or 2-3 mm; petals usually unlobed, sometimes absent; hypanthia 2-4 mm; wet meadows, fir forests in California and Oregon, rocky slopes in the Rocky Mountains | → 14 |
14. Styles 2-3 mm; petals linear, sometimes coiled, sometimes absent; hypanthia campanulate; capsules (1.8-)2-2.7 mm; ovaries 1/3 inferior; wet meadows, fir forests; California, Oregon. | Bensoniella |
14. Styles absent; petals elliptic to narrowly spatulate; hypanthia cylindric to obconic; capsules 6.5-10 mm; ovaries 1/2-3/4 inferior; rocky slopes; Rocky Mountains from Alberta to Colorado. | Conimitella |
15. Stamens 5 | → 16 |
15. Stamens 10 | → 19 |
16. Plants bearing bulbils at base of slender caudices, without rhizomes or stolons | → 17 |
16. Plants not bearing bulbils at bases of caudices, rhizomatous and, sometimes, stoloniferous | → 18 |
17. Sepals 3-10 mm; hypanthia 4-10 mm; capsules 8-11 mm; styles 1-2 mm; ovaries nearly superior; petals narrowly lanceolate, greenish with purple margins or reddish purple to dark purple. | Bolandra |
17. Sepals 1.5-3.5 mm; hypanthia 2.5-3.5 mm; capsules 4-7 mm; styles absent or to 1 mm; ovaries 1/2-3/4 inferior; petals elliptic to obovate, white or pink, purple, or violet. | Suksdorfia |
18. Seeds linear-fusiform, narrowly wing-margined, surfaces smooth; flowering stems and petioles glabrate or sparsely stipitate-glandular; cauline leaves glabrate; ovaries 1/2-4/5 inferior; petals 1.6-3.5 mm. | Sullivantia |
18. Seeds ellipsoid, not winged, surfaces usually tuberculate, smooth in 1 species; flowering stems and petioles usually densely stipitate-glandular and eglandular-pubescent; cauline leaves stipitate-glandular; ovaries 2/3 to completely inferior; petals 2-12(-15) mm. | Boykinia |
19. Anthers dehiscent by broad, terminal openings; carpels connate proximally; seeds fusiform, ribbed (at least over embryo). | Leptarrhena |
19. Anthers dehiscent by longitudinal slits; carpels usually connate in proximal 1/4-1/2; seeds oblong, ovoid, or ellipsoid, smooth, ribbed, tuberculate, papillate, or spiny | → 20 |
20. Hypanthia free from ovary 1-3.5 mm; stipules expanded from petiole bases; petals crimson-purple to violet-purple | Telesonix |
20. Hypanthia completely adnate to ovary or free from ovary to 0.2 mm; stipules barely expanded or absent; petals white, cream, greenish, yellow, yellowish green, orange, red, pink, or purple, sometimes red-tinged or with purple margins or tips; sepals usually green, sometimes purple, sometimes reddish at tips | → 21 |
21. Petioles jointed distally at attachment to leaf blades, separating early from blades; hairs unicellular; Siskiyou Mountains of California and Oregon, and sometimes in Washington. | Saxifragopsis |
21. Petioles not jointed distally at attachment to leaf blades, not separating from blades; hairs multicellular, or plants glabrous; widespread, mostly north-temperate, arctic, and alpine regions | → 22 |
22. Leaves cauline; flowering stems trailing or suberect, leafy; carpels connate proximally; seeds spiny; Coast Range to the western slopes of the Cascade Range from extreme nw California to sw Washington. | Cascadia |
22. Leaves basal, or basal and cauline; flowering stems ± erect, leafless or leafy; carpels connate in proximal 1/2; seeds smooth, tuberculate, papillate, or ribbed; mostly north-temperate, arctic, and alpine regions | → 23 |
23. Leaves usually basal; flowering stems usually leafless, rarely leaves crowded proximally at base of flowering stems; seeds ribbed. | Micranthes |
23. Leaves basal and cauline; flowering stems usually with reduced cauline leaves; seeds smooth, tuberculate, or papillate. | Saxifraga |
1. Inflorescences with all or some flowers replaced with bulbils | → 2 |
1. Inflorescences without bulbils | → 6 |
2. Plants tufted to mat-forming, with ± branched caudices or stolonlike rhizomes. | M. stellaris |
2. Plants usually solitary or tufted, with caudices | → 3 |
3. Leaf blade margins entire, subentire, or toothed distally; inflorescences narrow, cylindric or open; petals each with 1-2 yellow spots | → 4 |
3. Leaf blade margins coarsely toothed; inflorescences open; petals: 3 with 2 yellow spots and 2 without spots, or all not spotted | → 5 |
4. Leaf blades oblanceolate; pedicels erect to ascending. | M. foliolosa |
4. Leaf blades linear to elliptic; pedicels reflexed. | M. bryophora |
5. Leaf blades usually fleshy, margins usually with fewer than 12 coarse teeth; petioles indistinct; inflorescence bracts reduced; w North America | M. ferruginea |
5. Leaf blades thin, not fleshy, margins with 15+ lobelike teeth; petioles distinct; inflorescence bracts leaflike, gradually reduced distally; e North America. | M. petiolaris |
6. Ovaries ca. 1/2 inferior to inferior (sometimes appearing more superior in fruit) | → 7 |
6. Ovaries ± superior to at most 1/2 inferior (hypanthium to 1/3 adnate to ovary) | → 29 |
7. Leaf blade margins serrate or toothed distally; pistils connate 1/2+ their lengths | → 8 |
7. Leaf blade margins entire to subentire or apically denticulate, or crenulate, denticulate, serrate, or dentate on distal 2/3 to throughout; pistils connate to 1/2 their lengths | → 10 |
8. Leaf blades broadly obovate to round; petals ± clawed, 3.5-5 mm. | M. unalaschcensis |
8. Leaf blades rhombic to fan-shaped, sometimes nearly round, or oblanceolate to spatulate; petals not clawed, 2-4 mm | → 9 |
9. Leaf blades oblanceolate to narrowly oblanceolate or narrowly spatulate, sometimes ± narrowly obovate, margins (3-)5-7(-9)-toothed (teeth 0.5 mm); inflorescence axes and branches glabrous. | M. razshivinii |
9. Leaf blades rhombic to fan-shaped, sometimes nearly round, margins 7-11-toothed (teeth 1-3 mm); inflorescence axes glabrous or sparsely long-hairy, branches ± densely long-hairy. | M. calycina |
10. Petals (1-)5 and pink to purple, or 1-5 and white to greenish white or cream, or absent | → 11 |
10. Petals 5, white to greenish white, cream, or, rarely, purple, sometimes pink or purplish tinged | → 14 |
11. Inflorescences glomerate, congested; petals absent or white to greenish white. | M. apetala |
11. Inflorescences spikelike, constricted or open; petals white, cream, or pink to purple | → 12 |
12. Leaf blades ovate to elliptic, 2-6 cm. | M. hieraciifolia |
12. Leaf blades linear to elliptic, ovate to obovate, or oblanceolate, 3-25 cm | → 13 |
13. Inflorescences ± constricted to ± open thyrses; petals usually absent, sometimes 1-5, 1-2 mm; Rocky Mountains. | M. subapetala |
13. Inflorescences open, often lax thyrses; petals 5, 2-3 mm; e North America. | M. pensylvanica |
14. Leaf blades linear to oblanceolate or obovate, or elliptic to ovate; petioles indistinct | → 15 |
14. Leaf blades ± round to ovate or triangular, elliptic, or oblong, or, rarely, obovate, obtrullate, or deltate; petioles distinct | → 18 |
15. Inflorescences 3-10(-15) cm; petals shorter than sepals. | M. tempestiva |
15. Inflorescences usually 15-125 cm; petals equaling or longer than sepals, sometimes shorter | → 16 |
16. Leaf blade margins serrate to dentate, surfaces densely tangled-hairy; inflorescences flat-topped thyrses. | M. hitchcockiana |
16. Leaf blade margins entire or nearly so or serrulate to denticulate, surfaces glabrous, sparsely hairy, or densely short-hairy; inflorescences conic to cylindric thyrses | → 17 |
17. Leaf blade surfaces glabrous or sparsely hairy (margins ciliate); petals broadly elliptic to obovate and to 2 times as long as sepals, sometimes oblanceolate and equaling or shorter than sepals; w North America. | M. oregana |
17. Leaf blade surfaces short-hairy; petals linear to narrowly elliptic, longer than sepals; e North America. | M. pensylvanica |
18. Leaf blade margins serrate to crenate or dentate, rarely subentire | → 19 |
18. Leaf blade margins entire or subentire to crenulate or denticulate | → 24 |
19. Inflorescences lax, open (with distant lateral branches) | → 20 |
19. Inflorescences ± congested, glomerate or capitate to spicate | → 21 |
20. Sepals reflexed, sometimes spreading. | M. californica |
20. Sepals erect. | M. eriophora |
21. Inflorescences yellow- to cream-tipped stipitate-glandular; petals white, 1.5+ times as long as sepals. | M. rhomboidea |
21. Inflorescences purple- to red-tipped stipitate-glandular, sometimes glabrous proximally or glabrate distally; petals white, sometimes pink- or purple-tipped, margined, or tinged, equaling or slightly longer than sepals | → 22 |
22. Abaxial leaf surfaces glabrate (margins sometimes ciliate); petals white with purple margins, usually pink or purple tinged. | M. tenuis |
22. Abaxial leaf surfaces ± densely, tangled, reddish brown-hairy; petals white (sometimes pink tinged) | → 23 |
23. Inflorescences (5-)10-40-flowered, congested, almost capitate, (3-)7-20 cm; leaf blades ovate to ± round, sometimes elliptic or oblong; arctic and alpine North America | M. nivalis |
23. Inflorescences 3-10-flowered, subcapitate to spicate, 2-10 (-15) cm; leaf blades obtrullate or obovate to ovate; Gaspé Peninsula. | M. gaspensis |
24. Inflorescences at least somewhat congested, conic or capitate, 3.5-15(-35) cm | → 25 |
24. Inflorescences lax, cylindric to conic thyrses, (10-)15-50 cm | → 27 |
25. Carpels 3+. | M. texana |
25. Carpels 2(-3+) | → 26 |
26. Inflorescences densely stipitate-glandular; leaf blades narrowly to broadly ovate, surfaces hairy. | M. integrifolia |
26. Inflorescences sparsely stipitate-glandular; leaf blades obovate to elliptic, surfaces glabrous or sparsely hairy | M. aprica |
27. Inflorescences cylindric, with ± compact lateral cymules; petals 1-1.9 mm, equaling or shorter than sepals. | M. nidifica |
27. Inflorescences conic, with ± open cymules on lateral branches; petals 2-4 mm, longer than sepals | → 28 |
28. Plants solitary or in clumps, caudices often with bulbils; leaf blades usually longer than petioles. | M. integrifolia |
28. Plants often mat-forming, long, thin, rhizomatous; leaf blades usually equaling or shorter than petioles. | M. fragosa |
29. Leaves cauline, proximally crowded; sepals erect to spreading. | M. tolmiei |
29. Leaves basal; sepals reflexed, sometimes spreading or ascending to erect | → 30 |
30. Pistils connate 1/2+ their lengths | → 31 |
30. Pistils distinct almost to base | → 44 |
31. Capsules dark purple or purple-black | → 32 |
31. Capsules green to yellow and purple-tinged, purple, or distal 1/2 purple | → 36 |
32. Filaments club-shaped. | M. nelsoniana |
32. Filaments linear, flattened | → 33 |
33. Leaf blades somewhat reniform, ± evenly lobed, base cordate to truncate, margins entire; inflorescences sparsely purple-tipped stipitate-glandular. | M. nudicaulis |
33. Leaf blades round or obovate to oblanceolate or spatulate, or rhombic to fan-shaped, unlobed, base cuneate to attenuate, margins toothed distally; inflorescences densely tangled-hairy or glabrous | → 34 |
34. Leaf blades broadly obovate to round, base cuneate; petals 3.5-5 mm | M. unalaschcensis |
34. Leaf blades oblanceolate to narrowly oblanceolate or narrowly spatulate, or rhombic to fan-shaped, sometimes nearly round, base attenuate to cuneate; petals 2-4 mm | → 35 |
35. Leaf blades oblanceolate to narrowly oblanceolate or narrowly spatulate, sometimes ± narrowly obovate, margins (3-)5-7(-9)-toothed (teeth 0.5 mm); inflorescence axes glabrous, branches glabrous. | M. razshivinii |
35. Leaf blades rhombic or fan-shaped, margins 7-11-toothed (teeth 1-3 mm); inflorescence axes glabrous or sparsely long- hairy, branches ± densely long tangled hairy | M. calycina |
36. Leaf blades round, reniform, or spatulate to obovate; filaments ± club-shaped | → 37 |
36. Leaf blades linear or elliptic to oblanceolate, obovate, or spatulate; filaments linear, flattened | → 40 |
37. Leaf blades spatulate to obovate, base cuneate to slightly attenuate. | M. lyallii |
37. Leaf blades round to ovate or reniform, base cordate to truncate | → 38 |
38. Inflorescences open, lax thyrses. | M. odontoloma |
38. Inflorescences ± congested, spikelike to glomerulate, sometimes conic thyrses | → 39 |
39. Inflorescences ± congested, conic to glomerate thyrses; petals white to pinkish, rarely orange-spotted; filaments distinctly club-shaped. | M. nelsoniana |
39. Inflorescences spikelike thyrses; petals cream to yellowish; filaments narrowly club-shaped. | M. spicata |
40. Plants tufted or mat-forming, with ± branched caudices or stolonlike rhizomes; inflorescences open, lax cymes. | M. stellaris |
40. Plants solitary or tufted, with caudices; inflorescences cylindric or open, lax thyrses | → 41 |
41. Leaf blades linear to elliptic or oblanceolate, margins entire or subentire to 1-3-toothed distally; petals each with 1-2 yellow spots | → 42 |
41. Leaf blades spatulate to obovate or oblanceolate, margins coarsely toothed in distal 1/3+; petals: 3 with 2 yellow spots, 2 without spots | → 43 |
42. Leaf blades oblanceolate; pedicels erect to ascending. | M. foliolosa |
42. Leaf blades linear to narrowly elliptic; pedicels reflexed. | M. bryophora |
43. Leaves ± fleshy; petioles indistinct; blade margins usually with fewer than 12 coarse teeth; inflorescence bracts usually reduced; w North America. | M. ferruginea |
43. Leaves thin; petioles distinct; blade margins with 15+ lobelike teeth; inflorescence bracts leaflike; e North America. | M. petiolaris |
44. Petals white, each with 1-2 greenish to yellow spots (sometimes faded in dried material); filaments usually strongly club-shaped or petaloid | → 45 |
44. Petals white to greenish, sometimes purplish tipped or margined, usually not spotted; filaments linear, flattened or slightly club-shaped | → 49 |
45. Leaf blades lanceolate to oblanceolate, base attenuate; petioles ± indistinct (broad). | M. micranthidifolia |
45. Leaf blades ovate or elliptic to oblong, sometimes almost orbiculate, base ± attenuate to ± truncate; petioles distinct | → 46 |
46. Leaf blades densely white- or reddish brown-hairy; petal spots usually distinct even in dried material; filaments longer than petals | → 47 |
46. Leaf blades glabrate adaxially; petal spots often faded in dried material; filaments ± equaling petals | → 48 |
47. Leaf blade margins deeply dentate (teeth 2+ mm); inflorescences open, lax; e North America. | M. caroliniana |
47. Leaf blade margins shallowly serrate (teeth to 1 mm); inflorescences with flowers crowded at branch tips; nw North America. | M. reflexa |
48. Leaf blade margins crenate-serrate (teeth ca. 2 mm); inflorescences open, lax; filaments strongly club-shaped, sometimes petaloid. | M. marshallii |
48. Leaf blade margins shallowly serrate to dentate (teeth usually to 1 mm); inflorescences with flowers ± crowded at tips; filaments club-shaped, not petaloid. | M. idahoensis |
49. Sepals erect to ascending | → 50 |
49. Sepals ascending or spreading to strongly reflexed | → 52 |
50. Petal lengths ca. 2 times sepals; ovaries 1/3-1/2 inferior. | M. eriophora |
50. Petal lengths 2+ times sepals; ovaries ± superior | → 51 |
51. Leaf blade margins irregularly crenate to serrate. | M. virginiensis |
51. Leaf blade margins entire or subentire. | M. palmeri |
52. Leaf blade bases truncate; petals often with 2 faint yellow spots. | M. careyana |
52. Leaf blade bases attenuate to ± truncate; petals usually not spotted (rarely present) | → 53 |
53. Petals greenish, often purple-margined. | M. tischii |
53. Petals white | → 54 |
54. Bracts and sepals often tangled brown-hairy; inflorescences flat-topped. | M. rufidula |
54. Bracts and sepals glabrous, rarely sparsely tangled brown-hairy; inflorescences open and conic or ± flat-topped, or glomerulate | → 55 |
55. Leaf blades oblong to narrowly ovate; inflorescences 5-10(-20)-flowered; sepals strongly reflexed. | M. howellii |
55. Leaf blades ovate to elliptic; inflorescences usually (10-)30+-flowered; sepals ascending to spreading | → 56 |
56. Inflorescences with flowers crowded in 1+ glomerules, branches ascending; ovaries ± superior. | M. occidentalis |
56. Inflorescences open, lax, branches strongly divaricate; ovaries nearly 1/3 inferior. | M. gormanii |
- 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, PNW Herbaria
- WildflowerSearch
- iNaturalist (observations)
- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
