Ivesia sect. Ivesia
Rosaceae tribe Potentilleae
(0.2–)0.3–2(–4) dm.
alternate, rarely opposite, pinnately (palmately) compound (simple in Alchemilla, Aphanes, and Chamaerhodos);
stipules persistent (absent in Chamaerhodos), adnate to petiole;
venation pinnate or palmate.
usually loosely to very tightly cylindric (mousetail-like in I. muirii), rarely weakly planar (I. longibracteata);
stipules present;
leaflets overlapping, individually distinguishable or not, lobed to base, sparsely to densely hairy, sometimes glabrous or glabrate;
terminal leaflets indistinct.
(0–)1–3, sometimes paired;
blade usually ± reduced to vestigial, rarely well developed.
usually ± congested, sometimes becoming open in fruit, flowers mostly arranged in 1–few(–several in I. gordonii var. wasatchensis) loose to capitate glomerules.
remaining straight.
hypanthium shallowly cupulate or campanulate, sometimes turbinate (I. gordonii);
petals not medially reflexed, golden to pale yellow, sometimes white (I. utahensis) and then sometimes pink-tinged, not or scarcely clawed, apex acute to truncate, rounded, or emarginate;
stamens 5 (10 in I. pygmaea), anthers longer than wide, laterally dehiscent;
carpels (1–)2–15(–30 in I. pygmaea).
perianth and androecium perigynous;
epicalyx bractlets present, sometimes absent;
hypanthium usually patelliform, cupulate, or campanulate, sometimes turbinate, saucer-shaped, flat-bottomed, or subglobose to ellipsoid or ovoid;
torus flat to conic or turbinate, enlarged (absent or reduced in Alchemilla, Aphanes, and Chamaerhodos);
carpels 1–260, styles basal or lateral to subterminal, distinct;
ovules 1(or 2), basal.
aggregated achenes (achenes in Alchemilla and Aphanes);
torus sometimes fleshy;
styles deciduous or persistent, not elongate.
vertical, smooth or nearly so, not carunculate.
Ivesia sect. Ivesia
Rosaceae tribe Potentilleae
Species 8 (8 in the flora).
Species in sect. Ivesia tend to form compact rosettes or tufts in open montane to alpine areas, often where rocky but generally not growing in rock crevices (except Ivesia longibracteata). General characteristics of the section are an overall evident glandularity, loosely to tightly cylindric leaves (mousetail-like in I. muirii), relatively short ascending to erect stems, straight pedicels, and flowers that are typically congested into 1–few capitate clusters that sometimes become more open in fruit. The taproots of some species, especially I. lycopodioides, are markedly enlarged, an adaptation to alpine growing conditions. The inclusion of two anomalous species in the section, I. longibracteata and I. webberi, is tentative; it is also possible that I. cryptocaulis belongs here rather than in sect. Setosae.
Section Ivesia has its center of species diversity in the high Sierra Nevada of California, where Ivesia pygmaea, with its ten stamens and more open habit, is possibly transitional between sects. Ivesia and Setosae. Ivesia gordonii (the most widespread species), I. tweedyi, and I. utahensis form an arc around the northern Great Basin, as outliers from the core Sierran distribution of the section.
Some early floras treated Ivesia pygmaea and I. lycopodioides as varieties of I. gordonii (for example, W. H. Brewer et al. 1876–1880, vol. 1) or Potentilla gordonii (Hooker) Greene (W. L. Jepson [1923–1925], 1909–1943, vol. 2). Recent treatments follow D. D. Keck (1938) in recognizing all three as distinct species; some annotations and references are nevertheless carried over from the earlier expanded circumscription of I. gordonii.
Since Ivesia cryptocaulis is sometimes identified as a member of sect. Ivesia, it is included herein and keys out in the seventh couplet.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genera 14–22, species ca. 860 (14 genera, 189 species, including 1 hybrid, in the flora area).
The base chromosome number for Potentilleae is mostly x = 7 (8 in Alchemilla and Aphanes; 14 in Comarum).
Variation in the number of genera recognized in Potentilleae is due to differences in generic delimitation between D. Potter et al. (2007) and the authors of Potentilla and segregates here (see 9. Ivesia and 8. Potentilla for discussion). In the former, Duchesnea, Horkelia, Horkeliella, and Ivesia are included within Potentilla. Likewise, Aphanes is included within Alchemilla by Potter et al. while it is kept distinct here.
Potentilla and its segregates and Fragaria are host to Phragmidium rusts, but not the other genera of the tribe.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Epicalyx bractlets longer than sepals, 2.5–5 mm; leaves weakly planar to loosely ± cylindric; leaflets 5–6 per side; Castle Crags, n California. | I. longibracteata |
1. Epicalyx bractlets shorter than sepals, 0.5–3(–4 in I. gordonii) mm; leaves loosely to tightly cylindric; leaflets mostly 10–40 per side (4–10 in I. webberi); w United States | → 2 |
2. Plants silvery; leaves very tightly cylindric (mousetail-like, with leaflets scarcely distinguishable); leaflets 0.4–1 mm. | I. muirii |
2. Plants ± green; leaves loosely to tightly cylindric; leaflets distinguishable, (0.5–)2–13(–18) mm | → 3 |
3. Cauline leaves 2, paired; basal leaves: leaflets 4–8(–10) per side; petiole hairs 2–4 mm. | I. webberi |
3. Cauline leaves 0–2(–3), not paired; basal leaves: leaflets (6–)10–35 per side; petiole hairs 0.2–1.5 mm | → 4 |
4. Hypanthia turbinate to campanulate, (1.5–)2–4(–4.5) mm (± as deep as wide); petals narrowly oblanceolate to narrowly spatulate. | I. gordonii |
4. Hypanthia shallowly cupulate or shallowly campanulate, 1–2 mm (wider than deep); petals oblanceolate or broadly elliptic to spatulate or broadly obovate | → 5 |
5. Carpels (1–)2–6(–9); Idaho, Utah, Washington | → 6 |
5. Carpels (5–)8–30; e California, Nevada | → 7 |
6. Petals white, sometimes pink-tinged; stems prostrate to ascending; leaflets 2–4 mm; Utah. | I. utahensis |
6. Petals golden yellow; stems ascending to erect; leaflets 4–7(–10) mm; n Idaho, Washington. | I. tweedyi |
7. Plants diffusely matted; Spring Mountains, s Nevada. | I. cryptocaulis |
7. Plants rosetted to tufted or ± tightly matted; Sierra Nevada, White Mountains, and Sweetwater Mountains of e California and adjacent w Nevada | → 8 |
8. Stamens 10; sheathing bases usually ± strigose abaxially; taproots stout, not fleshy. | I. pygmaea |
8. Stamens 5; sheathing bases glabrous abaxially; taproots fusiform, fleshy. | I. lycopodioides |
1. Shrubs; leaf lobe margins entire; achenes hirsute. | Dasiphora |
1. Herbs, perennial, sometimes annual or biennial, or subshrubs; leaf lobe margins or apices ± toothed, sometimes entire; achenes glabrous (sometimes ± hairy) | → 2 |
2. Petals 0, sepals 4; achenes 1, enclosed in dry, urceolate or subglobose to ellipsoid or ovoid hypanthia | → 3 |
2. Petals and sepals usually 5; achenes 1–260, usually aggregated (sometimes on elongating tori), usually in (± open) patelliform, cupulate, campanulate, or turbinate hypanthia (not enclosed in dry hypanthium) | → 4 |
3. Herbs perennial; leaves basal, blades reniform to orbiculate, palmately lobed, sometimes palmately compound; stamens 4. | Alchemilla |
3. Herbs annual; leaves cauline, blades cuneate, deeply divided into segments, each lobed; stamen 1(or 2). | Aphanes |
4. Leaves all or mostly basal or proximal (if cauline, deeply pinnatifid), ternate or 2–4-ternate (sometimes simple and coarsely toothed apically in Sibbaldia) | → 5 |
4. Leaves basal or cauline, the latter usually reduced distally, odd-pinnate to palmate, rarely ternate or ± bipinnate | → 9 |
5. Tori becoming red and fleshy in fruit; leaf margins serrate to crenate | → 6 |
5. Tori hemispheric (not enlarged or fleshy) in fruit or absent; leaf margins entire or (2–)3(–5)-toothed apically | → 7 |
6. Leaves ± doubly serrate or crenate; stolons leafy; inflorescences: flowers solitary, axillary at stolon nodes; petals yellow. | Duchesnea |
6. Leaves serrate to crenate; stolons not leafy; inflorescences 1–10-flowered, cymes, axillary from leaf rosettes; petals usually white. | Fragaria |
7. Leaves pinnately compound or simple and deeply pinnatifid, margins entire, stipules absent. | Chamaerhodos |
7. Leaves ternate, margins toothed apically, stipules persistent | → 8 |
8. Petals ± yellow; stamens 5. | Sibbaldia |
8. Petals usually white; stamens 20(–30). | Sibbaldiopsis |
9. Petals deep red to purple, rarely pink, shorter than sepals; tori enlarged and spongy at maturity; horizontal stems sometimes floating, wetland habitats. | Comarum |
9. Petals yellow to white, rarely pink or red (then equal to or longer than sepals); tori not enlarged and spongy at maturity; stems erect to decumbent, not horizontal or floating even if in wetlands | → 10 |
10. Anthers dehiscing by continuous marginal slit (with a single theca); styles sub-basal. | Drymocallis |
10. Anthers dehiscing longitudinally; styles subterminal to lateral | → 11 |
11. Hypanthium patelliform to campanulate or cupulate to turbinate (not flat-bottomed); filaments not forming tube; petals white to yellow, sometimes reddish or pink tinged | → 12 |
11. Hypanthium ± cupulate or bluntly campanulate and flat-bottomed; filaments forming tube; petals usually white, sometimes pink-tinged, rose-veined, or cream | → 13 |
12. Plants not aromatic; leaves ± cordate or reniform to narrowly elliptic in outline, leaflets 3–15(–41); petals oblanceolate or obovate to obcordate to nearly round, rarely elliptic; carpels 3–260. | Potentilla |
12. Plants often aromatic; leaves planar to cylindric, leaflets (3–)7–161; petals linear or narrowly oblanceolate to obovate, sometimes obcordate; carpels 1–20(–40). | Ivesia |
13. Stamens 10; leaflets (3–)5–41. | Horkelia |
13. Stamens 20; leaflets 30–70. | Horkeliella |
