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California Mountain Ashe, California mountain-ash

Swedish whitebeam

Habit Shrubs, 10–20(–40) dm. Trees, to 70[–200] dm.
Stems

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.

1;

bark gray;

winter buds green to red-brown, ovoid, 5–12 mm, shiny, slightly glutinous, whitish-villous.

Leaves

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.

simple;

stipules early deciduous, densely whitish-villous;

blade shiny, green to dark green adaxially, ovate to elliptic, 6–13 × 3.5–8.5 cm, margins proximally 4–7 pinnately lobed, lobes ± oblong, 1–1.5(–1.8) cm wide, basal sinuses deepest, margins distally coarsely serrate, main pairs of secondary veins 8–10, apex acute to obtuse, abaxial surface white-tomentose, adaxial glabrous or sparsely villous, indument usually persistent.

Panicles

25–120+-flowered, rounded, 3–11 cm diam.;

peduncles glabrous or sparsely hairy.

18–85-flowered, rounded, 6–17 cm diam.;

peduncles white-tomentose.

Pedicels

glabrous or sparsely hairy; fruiting pedicels essentially glabrous.

white-tomentose.

Flowers

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.

14–16 mm diam.;

hypanthium whitish-tomentose, hypanthium plus sepals 5–6 mm;

sepals 1.5–2.5 mm, margins villous and eglandular, rarely with inconspicuous glands;

petals white, elliptic to broadly ovate, 5–7 mm;

stamens 20;

carpels distinct, apex conic, styles 2, 2.5–4 mm.

Infructescences

glabrous or nearly so.

thinly white-tomentose to glabrate.

Pomes

bright red, globose to subglobose, 6–9 mm diam., shiny if glaucous layer is rubbed off;

sepals inconspicuous, incurved.

bright red, ellipsoid, sometimes narrowly obovoid, 7–16 × 6–11 mm, shiny, faintly glaucous;

lenticels few;

sepals inconspicuous, erect, villous toward apex.

Seeds

red-brown, lanceolate, 4 × 2 mm, slightly asymmetric, slightly flattened.

red-brown, narrowly ovoid, 6–6.5 × 2.5–3.1 mm, slightly asymmetric, slightly flattened.

2n

= 68 (Europe).

Sorbus californica

Sorbus intermedia

Phenology Flowering spring; fruiting fall. Flowering spring; fruiting fall.
Habitat Mountain slopes, meadows, stream banks, lakeshores, sun or shade Thickets, roadsides, waste ground, disturbed conifer forests
Elevation 1500–3400 m (4900–11200 ft) 0–100 m (0–300 ft)
Distribution
from FNA
CA; NV; OR
[WildflowerSearch map]
[BONAP county map]
from FNA
MA; WA; BC; ON; Europe [Introduced in North America]
[BONAP county map]
Discussion

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.)

Sorbus aria (Linnaeus) Crantz of Europe has been reported from San Juan County, Washington (S. Atkinson and F. Sharpe 1993; J. T. Kartesz and C. A. Meacham 2003). Those populations are S. intermedia, with more deeply lobed leaves and broader winter buds.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 9, p. 441. FNA vol. 9, p. 437.
Parent taxa Rosaceae > subfam. Amygdaloideae > tribe Maleae > Sorbus > subg. Sorbus > sect. Commixtae Rosaceae > subfam. Amygdaloideae > tribe Maleae > Sorbus > subg. Aria
Sibling taxa
S. americana, S. aucuparia, S. decora, S. hybrida, S. intermedia, S. sambucifolia, S. scopulina, S. sitchensis, S. torminalis
S. americana, S. aucuparia, S. californica, S. decora, S. hybrida, S. sambucifolia, S. scopulina, S. sitchensis, S. torminalis
Synonyms S. sitchensis subsp. californica Pyrus intermedia, Aria intermedia
Name authority Greene: Pittonia 4: 131. (1900) (Ehrhart) Persoon: Syn. Pl. 2: 38. (1806)
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