Sorbus hybrida |
Sorbus aucuparia |
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hybrid mountain ash, oak-leaf mountain-ash, Swedish mountain-ash, Swedish service-tree |
European mountain-ash, rowan, rowan-berry, sorbier des oiseaux, sorbier des oiseleurs |
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Habit | Trees, 30–120 dm. | Trees, 60–150 dm. |
Stems | single or multistemmed; bark gray; winter buds brownish to purple, ovoid to ovoid-conic, 4–10 mm, dull, not glutinous, densely white-villous, at least distally and on scale margins. |
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. |
Leaves | proximally pinnately compound, lobed distally; stipules deciduous or persistent, often white-villous; blade paler green abaxially, dull green adaxially, ovate to oblong-ovate, rarely oblong, 7–13 × 5–11 cm, pinnately lobed with (1 or)2(or 3) pairs of sessile or decurrent, free, oblong leaflets, terminal leaflets 7–10-lobed, margins serrate at least distally, lobe and leaflet apex acute or obtuse, lateral veins 7–10 pairs, abaxial surface whitish-tomentose. |
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. |
Panicles | 25–75-flowered, flat-topped or rounded, 4.5–10 cm diam.; peduncles white-villous. |
75–200+-flowered, flat-topped or rounded, 6–18 cm diam.; peduncles ± whitish-villous. |
Pedicels | white-villous. |
densely whitish-villous. |
Flowers | 10–15 mm diam.; hypanthium tomentose, hypanthium plus sepals 5–7.5 mm; sepals 1.5–4 mm, margins usually entire, rarely with inconspicuous glands; petals white, suborbiculate, broadly obovate, broadly ovate, or broadly elliptic, 5–7 mm; stamens 20; carpels 1/2 adnate to hypanthium, apex conic, styles 2 or 3, 2–3 mm. |
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. |
Infructescences | glabrate to villous. |
glabrous or densely villous. |
Pomes | red, globose to subglobose, 8–15 mm diam., shiny, not glaucous; sepals inconspicuous, incurved. |
yellow or orange-red to red, globose to subglobose, 8–12 mm diam., shiny or dull, slightly glaucous or not; sepals inconspicuous, incurved. |
Seeds | red-brown, ovoid, 5–6 × 2 mm, asymmetric, slightly flattened. |
brown, ovoid to ovoid-lanceoloid, 3–4.5 × 1.5–2 mm, asymmetric, slightly flattened. |
2n | = 68. |
= 34. |
Sorbus hybrida |
Sorbus aucuparia |
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Phenology | Flowering spring; fruiting fall. | Flowering spring; fruiting fall. |
Habitat | Woods, rocky slopes, disturbed ground and edges near towns | Thickets, roadsides, woods, other habitats near towns, scattered in remote natural settings |
Elevation | 0–1000 m (0–3300 ft) | 0–2100 m (0–6900 ft) |
Distribution |
UT; VT; WA; NB; n Europe [Introduced in North America]
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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)]
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Discussion | Sorbus hybrida is considered an apomictic tetraploid producing fully fertile pollen and seed and subject to dispersal. An almost undistinguishable European taxon, S. ×thuringiaca (Ilse) Fritsch, often confused with S. hybrida, has been reported for New Hampshire and Vermont. Described as an unstable diploid hybrid between S. aria and S. aucuparia, S. ×thuringiaca has oblong leaves, 1–3(–5) pairs of free leaflets, 10–12(–13) pairs of lateral veins, and produces sterile pollen and relatively few viable seeds. Uncritical reports of escaped S. ×thuringiaca in North America should be considered doubtful; they probably refer to the more likely S. hybrida. The authors have not seen a specimen to document a report of S. hybrida from Montana. Sorbus hybrida is placed in subg. Sorbus following J. J. Aldasoro et al. (2004), based on leaf division and pome characteristics, including the lack of tanniferous cells in parenchyma, lack of starch, and relatively small sclereid groups. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 9, p. 438. | FNA vol. 9, p. 438. |
Parent taxa | Rosaceae > subfam. Amygdaloideae > tribe Maleae > Sorbus > subg. Sorbus > sect. Sorbus | Rosaceae > subfam. Amygdaloideae > tribe Maleae > Sorbus > subg. Sorbus > sect. Sorbus |
Sibling taxa | ||
Synonyms | Pyrus aucuparia, S. subvestita | |
Name authority | Linnaeus: Sp. Pl. ed. 2, 1: 684. (1762) | Linnaeus: Sp. Pl. 1: 477. (1753) |
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