Sorbus scopulina
Sorbus californica
Cascade mountain-ash, Greene's Mountain ash, mountain ash, Rocky Mountain ash, Rocky Mountain Mountain ash, Rocky Mountain or Cascade Mountain ash, Rocky Mountain or Cascade or Greene's Mountain Ashe, western mountain-ash
California Mountain Ashe, California mountain-ash
1–8;
bark gray, sometimes yellowish or reddish purple, or grayish red;
winter buds olive brown to red-brown, conic, 8–14 mm, shiny, slightly glutinous, glabrous or sparsely or densely whitish-villous.
1–8;
bark dark gray;
winter buds red to brown, shiny, conic, 5–12 mm, slightly glutinous, sparsely hairy except along scale margins and apex, hairs rufous.
pinnately compound;
stipules deciduous or persistent, hairs whitish;
blade paler abaxially, shiny, green to dark green adaxially, leaflets 7–13(–15), opposite or subopposite, lanceolate, oblong, narrowly ovate, oblanceolate, or obovate, (3–)4–6.5(–8.7) × 1.5–2.7 cm, l/w ratio 2.1–4.4, margins finely serrate, apex obtuse, acute, or acuminate, surfaces glabrous, leaf and leaflet axils hairy, hairs whitish.
pinnately compound;
stipules often persistent, margins rufous-hairy;
blade pale abaxially, shiny, green adaxially, leaflets 7–9(–11), opposite or subopposite, oblong to elliptic, sometimes narrowly elliptic, 2.5–4.1(–4.5) × 0.9–2 cm, l/w ratio 2.1–2.6, margins finely to coarsely serrate, sometimes doubly serrate, apex obtuse to acute, surfaces soon glabrous, leaflet axils and petiole bases hairy, hairs rufous.
40–200+-flowered, flat-topped to rounded, 5–15 cm diam.;
peduncles sparsely to densely whitish-villous.
25–120+-flowered, rounded, 3–11 cm diam.;
peduncles glabrous or sparsely hairy.
sparsely to densely whitish-villous (in flower and fruit).
glabrous or sparsely hairy; fruiting pedicels essentially glabrous.
11–13 mm diam.;
hypanthium nearly glabrous or densely villous, hypanthium plus sepals 3–4 mm;
sepals 0.8–2.3 mm, margins lightly to densely whitish-villous, glands absent or sparse and usually inconspicuous;
petals white, ovate, 4–6 mm;
stamens (14–)20;
carpels distinct, apex conic, styles 3 or 4, 2–2.5 mm.
9–10 mm diam.;
hypanthium glabrous, hypanthium plus sepals 3 mm;
sepals 0.7–1.5 mm, margins ciliolate, hairs whitish, irregularly glandular;
petals white, broadly ovate, 3–4 mm;
stamens 20;
carpels distinct, apex conic, styles 3 or 4, 1.5–2 mm.
whitish-villous, rarely glabrous with age.
glabrous or nearly so.
bright orange to reddish orange, globose, subglobose, broadly obovoid, or broadly elliptic, 8–12.1 × 7.5–12.8 mm, shiny, sometimes lightly glaucous;
sepals inconspicuous, incurved.
bright red, globose to subglobose, 6–9 mm diam., shiny if glaucous layer is rubbed off;
sepals inconspicuous, incurved.
brown, narrowly ovoid, 3.8–5.4 × 1.7–2.8 mm, slightly asymmetric, slightly flattened.
red-brown, lanceolate, 4 × 2 mm, slightly asymmetric, slightly flattened.
= 34, 68.
Sorbus scopulina
Sorbus californica
Sorbus scopulina is variable, especially in leaflet shape, number, and indument. Plants with narrower leaflets were separated as S. angustifolia; plants with broader leaflets were segregated as S. andersonii and S. cascadensis. Densely hairy forms were named S. dumosa. All represent points on a morphologic continuum, united by their shiny leaflets, whitish indument, and western range. Sparsely hairy forms approach the more southern S. californica but have whitish axillary hairs and larger leaflets than that species, which has rufous axillary hairs and leaflets less than 4 cm. Most S. scopulina have shiny hypanthia and fruits. Occasional collections, all within the range of S. sitchensis, are glaucous-fruited. This may be natural variation, or it could represent introgression from S. sitchensis. H. A. McAllister (2005, pers. comm.) found that individuals of S. scopulina from cordilleran Idaho and Arizona were sexual diploids; plants from the Cascade and Coast ranges of British Columbia and Washington were tetraploid and presumably apomictic. Here, these entities are synonymized, awaiting a larger study that might correlate distinct morphologic characteristics with the ploidy levels. J. J. Aldasoro et al. (1998, 2004) noted that some European Sorbus species are both diploid and tetraploid, suggesting that sexual species occasionally produce spontaneous agamospermous individuals.
The intergeneric hybrid ×Amelasorbus jackii Rehder [Amelanchier alnifolia (Nuttall) Nuttall ex M. Roemer × Sorbus scopulina] has been collected in Idaho and Oregon. Foliage of the Idaho collection is very similar to that of Amelanchier, with basal pinnae inconspicuous and infrequent, suggesting that this hybrid may be overlooked.
The illegitimate later homonym Sorbus alaskana G. N. Jones pertains here.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Sorbus californica is recognized here in the narrow sense, occurring north to Crater Lake National Park, Oregon (P. F. Zika 2003). The concept in H. A. McAllister (2005) differs, including plants of British Columbia and Washington treated here as S. scopulina. Sorbus californica is distinct in its shiny leaflets less than 4 cm with rufous hairs in the axils. Where their ranges overlap, S. scopulina has hairier inflorescences, leaflets usually more than 4.5 cm, and whitish axillary hairs. The small leaflets and essentially glabrous inflorescences help distinguish S. californica from putative hybrids between S. scopulina and S. sitchensis found farther north, which are otherwise similar with their somewhat shiny leaflets, slightly glaucous fruits, and red axillary hairs. Some collections of S. californica from California are intermediate with either S. sitchensis or S. scopulina and may represent hybrids with those two species.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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