Sorbus decora

Northern Mountain Ash

Northern Mountain Ash
Photo courtesy Wisconsin State Herbarium
and Emmet J. Judziewicz

Flora, fauna, earth, and sky...
The natural history of the northwoods


Name:

  • Sorbus, from the Latin name for Sorbus domestica, the common European Mountain Ash or "Service Tree"
  • decora, from the Latin decoratus, "decorated"
  • Common Name, from its northern range and the similarity of its compound leaves to those of the true Ash (Fraxinus spp).
  • Other common names include Showy Mountain Ash, Western Mountain Ash, Sorbier décoratif (Qué)

Taxonomy:

  • Kingdom Plantae, the Plants
    • Division Magnoliophyta, the Angiosperms (flowering plants)
      • Class Magnoliopsida, the Dicotyledons
      • Subclass Rosidae, the Roses
        • Order Rosales, the Roses
          • Family Rosaceae, the Roses; with Amelanchier (Juneberries), Aronia (Chokeberries), Crataegus (Hawthorns), Malus (Apples), Physocarpus (Ninebark), Potentilla (Cinquefoils), Prunus (Cherries & Plums), Rubus (Blackberries, Dewberries, and Raspberries), and Spiraea (Spirea)
            • Genus Sorbus, the Mountain Ash
  • Taxonomic Serial Number: 25322
  • Also known as Pyrus decora, Pyrus americana var. decora

Description:

  • A native, deciduous shrub or small tree, 20'-30' tall.
  • Leaves alternate, compound, with 13-17, toothed or doubly toothed leaflets, which are only 1½" - 3" llong, and 5/8" - 1 1/8" wide.
  • Stem
    • Trunk short and slender
    • Branches spreading, to form a narrow, open, and round topped crown.
    • Bark thin and smooth
    • Bud Scales: outer scales are sticky; inner scales are hairy.
  • Roots fibrous
  • Flowers numerous in showy round or flat-topped clusters 5-15 cm diameter; individual, 5-petaled flowers, small, 6-8 mm wide; appearing June and July.
  • Fruit scarlet berries to ½" in diameter, in loose clusters; ripening in August and September.

Identification:

  • Identifiable as a Mountain Ash by the toothed compound leaves.
  • Distinguished from the only other North Woods trees with compound leaves, the true Ash, by the toothed leaf edges. Green Ash (Fraxinus pennsylvanica) and Black Ash (Fraxinus nigra) have smooth leaf edges.
  • Distinguished from the very similar American Mountain Ash (Sorbus americana) by:
    • Lateral leaflets averaging less than 3 times as long as wide, more rounded at the base, and smooth on both upper and lower surfaces (Sorbus americana leaves are hairy on the undersides).
    • Slightly larger fruits which are orange/red rather than bright red.
  • Field Marks
    • Toothed, compound leaves
    • Bright orange/red berries in fall

Distribution:

  • Manitoba to Newfoundland, south to Minnesota, Iowa, Illinois, Indiana, Ohio, Pennsylvania, and New York.

Habitat:

  • Swampy or damp woods and borders, rocky slopes, shores.
  • This is normally a northern species of the sub-climax to climax northern coniferous forests.

Fire:

  • Not well adapted to survive fire; it is small, has thin bark, and occurs largely in areas that do not burn at frequent intervals.

Associates:

  • Trees: Red Maple (Acer rubrum)
  • Shrubs: Alder (Alnus spp.), Labrador Tea (Ledum groenlandicum), Moose Maple (Acer spicatum)
  • Birds: Berries are a preferred food source of Ruffed Grouse, American Robin, European Starling, Cedar Waxwing, Common Grackle and Pine Grosbeak.

History:

  • The Cree used a decoction of inner bark from the stem base for rheumatism and back ache.

Uses:

  • Although the leaves are poisonous, the fruit can be eaten by humans and is rich in iron and Vitamin C. Berries are most often used in jellies.
  • The berries are said to have a superior flavor to those of the American Mountain Ash, with the best flavor obtained after frost.
  • The fruit of both Mountain Ash species is used to make homemade wines.

Reproduction:

  • Sexually by seed

Propagation:

  • By seed,

Cultivation:

  • Hardy to USDA Zone 2 (average minimum annual temperature -50ºF)
  • Cultural Requirements
    • Full sun to partial shade.
    • well drained fertile soil.
  • Size 25'W x 20'H
  • Growth rate 12 to 18 inches per year

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Last updated on 4 March, 2006