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European mountain-ash, rowan, rowan-berry, sorbier des oiseaux, sorbier des oiseleurs

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

Habit Trees, 60–150 dm. Shrubs, 10–50(–80) dm.
Stems

1–3(or 4);

bark gray to bronze;

winter buds purple, ovoid to ovoid-conic, 5–15 mm, dull, not glutinous, usually densely villous, hairs whitish, rarely rufous, outer scales sometimes merely ciliate.

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.

Leaves

pinnately compound;

stipules deciduous or persistent, whitish-villous or glabrate;

blade paler or often whitish abaxially, dull green to bluish green adaxially, leaflets 11–17(–19), opposite, oblong to oblong-lanceolate or oblanceolate, (2.5–)3–6(–7.5) × 1.5–2 cm, l/w ratio 2.4–3.7, margins serrate at least in distal 1/2, often almost to base, apex acute to obtuse, abaxial surface white-tomentose to villous at flowering, indument often persisting, at least along midveins, leaflet axils, and petiole bases, hairs usually whitish, sometimes 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.

Panicles

75–200+-flowered, flat-topped or rounded, 6–18 cm diam.;

peduncles ± whitish-villous.

40–200+-flowered, flat-topped to rounded, 5–15 cm diam.;

peduncles sparsely to densely whitish-villous.

Pedicels

densely whitish-villous.

sparsely to densely whitish-villous (in flower and fruit).

Flowers

8–11 mm diam.;

hypanthium densely villous, hairs whitish, hypanthium plus sepals 2.9–3.2 mm;

sepals 0.5–1 mm, margins often glandular;

petals white, orbiculate, (3–)4–5 mm;

stamens 15–20;

carpels 1/2 adnate to hypanthium, apex conic, styles 3 or 4, 1.5–3 mm.

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.

Infructescences

glabrous or densely villous.

whitish-villous, rarely glabrous with age.

Pomes

yellow or orange-red to red, globose to subglobose, 8–12 mm diam., shiny or dull, slightly glaucous or not;

sepals inconspicuous, incurved.

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.

Seeds

brown, ovoid to ovoid-lanceoloid, 3–4.5 × 1.5–2 mm, asymmetric, slightly flattened.

brown, narrowly ovoid, 3.8–5.4 × 1.7–2.8 mm, slightly asymmetric, slightly flattened.

2n

= 34.

= 34, 68.

Sorbus aucuparia

Sorbus scopulina

Phenology Flowering spring; fruiting fall. Flowering spring; fruiting fall.
Habitat Thickets, roadsides, woods, other habitats near towns, scattered in remote natural settings Mountain slopes, open forests, forest edges, riparian zones, lakeshores
Elevation 0–2100 m (0–6900 ft) 0–3300 m (0–10800 ft)
Distribution
from FNA
AK; CA; CO; CT; DC; IA; ID; IL; IN; MA; MD; ME; MI; MN; MT; ND; NE; NH; NJ; NY; OH; OR; PA; RI; SC; SD; UT; VT; WA; WI; WV; WY; AB; BC; NB; NF; NS; ON; PE; QC; SK; SPM; Eurasia; n Africa; Atlantic Islands (Iceland, Madeira) [Introduced in North America; introduced also in Pacific Islands (New Zealand)]
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; AZ; CA; CO; ID; MT; NM; NV; OR; SD; UT; WA; WY; AB; BC; NT; SK; YT
[WildflowerSearch map]
[BONAP county map]
Discussion

Sorbus aucuparia is a commonly planted ornamental tree that is widely bird-disseminated. The species is often confused with S. decora, from which it differs by its ovoid and usually densely whitish-villous and nonglutinous winter buds and by its densely villous flowering pedicels and hypanthia. The leaflets of S. aucuparia are often tomentose abaxially at flowering; those of S. decora are glabrous or sparsely villous. Examination of leaflet serration is also useful; S. decora exhibits a prolonged apical tooth; it is no longer than the lateral ones in S. aucuparia. The lateral teeth are relatively finer and sharper in S. decora compared to those of S. aucuparia. At a magnification of at least 70× , leaflets of S. aucuparia are reportedly minutely papillose abaxially; those of S. decora are not papillose (H. A. McAllister 2005). Natural hybrids with S. decora have been reported by G. N. Jones (1939) (one fruiting specimen found near Opeongo Lake, Algonquin Park, Ontario), with Aronia arbutifolia [x\Sorbaronia hybrida (Moench) C. K. Schneider; synonyms A. hybrida (Moench) Zabel, Sorbus spuria Persoon] in Truro, Nova Scotia, and also in Maine, New Hampshire, and Vermont (D. W. Magee and H. A. Ahles 1999), and with A. melanocarpa (x\Sorbaronia fallax C. K. Schneider) in Maine and Massachusetts. Other nothospecies names for putative intergeneric hybrids involving S. aucuparia include: ×Crataegosorbus miczurinii Pojarkova (Crataegus sanguinea Pallas × S. aucuparia), and ×Sorbocotoneaster pozdnjakovii Pojarkova (Cotoneaster melanocarpus (Ledebour) Loddiges, G. Loddiges & W. Loddiges ex M. Roemer × S. aucuparia [as S. sibirica Hedlund]). Subspecies of Sorbus aucuparia were recognized by McAllister; the authors made no attempt to identify specimens infraspecifically. Sorbus subvestita Greene is variably considered to be a synonym of S. aucuparia (Jones) or S. decora (M. L. Fernald 1950; H. A. Gleason and A. Cronquist 1991). However, Jones explicitly cited the isotype of S. subvestita in his specimen citation for S. aucuparia along with an acknowledgement of the confusion with S. decora.

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

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.)

Source FNA vol. 9, p. 438. FNA vol. 9, p. 442.
Parent taxa Rosaceae > subfam. Amygdaloideae > tribe Maleae > Sorbus > subg. Sorbus > sect. Sorbus Rosaceae > subfam. Amygdaloideae > tribe Maleae > Sorbus > subg. Sorbus > sect. Commixtae
Sibling taxa
S. americana, S. californica, 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. intermedia, S. sambucifolia, S. sitchensis, S. torminalis
Synonyms Pyrus aucuparia, S. subvestita S. andersonii, S. angustifolia, S. cascadensis, S. dumosa, S. scopulina var. cascadensis
Name authority Linnaeus: Sp. Pl. 1: 477. (1753) Greene: Pittonia 4: 130. (1900)
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