Tsuga canadensis 'Coles Prostrate'

(Cole's Prostrate Canadian Hemlock, Cole's Prostrate Eastern Hemlock)

Overview:

Originally found in New Hampshire, this is a true prostrate form that creeps along the ground and spreads widely. It appreciates light shade.

Taxonomy

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Domain: Eukaryota Whittaker & Margulis,1978 - eukaryotes
- Kingdom: Plantae Haeckel, 1866 - Plants
  - Subkingdom: Viridaeplantae Cavalier-Smith, 1981 - Green Plants
    - Phylum: Magnoliophyta Cronquist, Takhtajan & W. Zimmermann, 1966 - Flowering Plants
      - Subphylum: Spermatophytina (auct.) Cavalier-Smith, 1998 - Seed Plants
        Infraphylum: Gymnospermae auct.
        Class: Pinopsida
        Order: Pinales - Conifers
        Family: Pinaceae (py-NAY-see-ay) Lindley, 1836, nom. cons. - Pine Family
        Subfamily: Abietoideae
        Genus: Tsuga (Endlicher) CarriÃ¨re, 185. 1855 - Hemlock [Japanese tsuga, name for native hemlocks of Japan]
        Specific epithet: canadensis (Linnaeus) Carr.
        Cultivar: Coles Prostrate
        Botanical name: Tsuga canadensis 'Coles Prostrate' (Linnaeus) Carr.

Notes:

A tentatively accepted name in the RHS Horticultural Database.

Physical Description

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Family Pinaceae:

Trees or rarely shrubs, evergreen or deciduous, monoecious. Branchlets often dimorphic: long branchlets with clearly spirally arranged, sometimes scalelike leaves; short branchlets often reduced to slow growing lateral spurs bearing dense clusters of leaves at apex. Leaves solitary or in bundles of (1 or) 2-5(-8) when basally subtended by a leaf sheath; leaf blade linear or needlelike, not decurrent. Cones unisexual. Pollen cones solitary or clustered, with numerous spirally arranged microsporophylls; microsporophyll with 2 microsporangia; pollen usually 2-saccate (nonsaccate in Cedrus, Larix, Pseudotsuga, and most species of Tsuga) . Seed cones erect or pendulous, maturing in 1st, 2nd, or occasionally 3rd year, dehiscent or occasionally indehiscent, with many spirally arranged ovulate scales and bracts; ovulate scales usually smaller than bracts at pollination, with 2 upright ovules adaxially, free or only basally adnate with bracts, maturing into seed scales. Seed scales appressed, woody or leathery, variable in shape and size, with 2 seeds adaxially, persistent or deciduous after cone maturity. Bracts free or adnate basally with seed scales, well developed or rudimentary, exserted or included. Seeds terminally winged (except in some species of Pinus) . Cotyledons 2-18. Germination hypogeal or epigeal. 2n = 24* (almost always) .

Ten or eleven genera and ca. 235 species: N hemisphere; ten genera (two endemic) and 108 species (43 endemic, 24 introduced) in China.

Species of the Pinaceae are among the most valuable and commercially important plants in the world. Most species are trees, and are often excellent sources of lumber, wood products, and resins; many are cultivated for afforestation and as ornamentals.^[1]

Genus Tsuga:

Trees evergreen; crown conic; leading shoot usually drooping. Bark gray to brown, scaly, often deeply furrowed. Branches horizontal, often tending to be arranged in flattened "sprays" and arched downward; short (spur) shoots absent; young twigs and distal portions of stem flexuous and pendent, roughened by peglike projections persisting after leaves fall. Buds mostly rounded at apex, not resinous. Leaves borne singly, persisting several years, ± 2-ranked or radiating in all directions, flattened to somewhat angular; abruptly narrowed to a petiolelike base, set on peglike projections, these angled, projected forward, sheath absent; apex rounded or notched; resin canals 1. Cones borne on year-old twigs. Pollen cones solitary, globose, brown. Seed cones maturing in 1 year, shedding seeds and falling soon thereafter or persisting for several years, pendent, ovoid, oblong, or oblong-cylindric, sessile or nearly so; scales persistent, shape various, thin, leathery, lacking apophysis and umbo; bracts small, included. Seeds winged; cotyledons 4--6. x =12.

Species ca. 10: Northern Hemisphere.

Species of Tsuga are found naturally in areas of relatively moist climates where water stresses are minimal. Most are conspicuous, if not dominant, members of the communities in which they occur.

Hemlock wood is moderately strong and pliable and lacks resin ducts. With the decline of associated species considered superior in commercial value, hemlocks have become important in the timber industry, especially for pulp. Hemlocks are also widely used for horticultural purposes; numerous cultivars have been developed.^[2]

ID Features: Pyramidal, medium-sized, needle evergreen tree with horizontal to. pendulous, graceful branches. Short flattened needles. Needles held in 2-ranked fashion. T. caroliniana, with which T. canadensis is often confused,. has more of its needles spirally distributed around its shoots. Shoots pubescent. Has minutely serrulate leaf margins, while T. caroliniana has. smooth margins. Twigs roughened by persistent leaf bases remaining after needles fall. Numerous, small cones. •

Habit: Evergreen.

Flowers: Monoecious, with male and female flowers. Small and not ornamentally important. • Bloom Period: January, February, March. • Flower Color: bronze, brown, cream, tan

Seeds: Fruit: Small cones, about 0.5" to 1.0" long. Turning light brown in the fall. Can be borne in large numbers.

Foliage: Summer foliage: Leaves are spirally arranged, but are held in a 2-ranked fashion. Needles are flattened. Needles are 0.25" to 0.75" long and about 0.10" wide. New foliage is dark green above with 2 whitish bands on the underside. Leaf margins minutely serrulate. Shoots pubescent. • Fall foliage: Evergreen, no fall color.

Distribution

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Landscaping

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Landscape Uses: Lawn tree. Specimen. Can be sheared to form an effective screen or hedge. Excellent evergreen for screening use in shaded locations where most. needle evergreens fail. In groves or small groupings. Dwarf forms as rock garden plants, accent plants or foundation plants. • Liabilities: Not tolerant of pollution. Not tolerant of salt spray. Spider mites. Deer like to browse the foliage or rub off the bark with their antlers. Not tolerant of heat or drought. Hemlock wooly adelgid is a new and devastating insect pest that can be. easily controlled, but left unchecked can kill large plants in 3 years.

Growth

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Culture: Space 4-6' apart.

Soil: Minimum pH: 6.1 • Maximum pH: 7.8

Sunlight: Sun Exposure: Sun to Partial Shade.

Temperature: Cold Hardiness: 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b. (map)

Similar Species

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Members of the genus Tsuga:

Bibliography

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Cheng Wan-chün, Fu Li-kuo, Law Yu-wu, Fu Shu-hsia, Wang Wen-tsai, Chu Cheng-de, Chao Chi-son & Chen Chia-jui. 1978. Pinaceae. In: Cheng Wan-chün & Fu Li-kuo, eds., Fl. Reipubl. Popularis Sin. 7: 32-281.

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Notes

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Contributors:

Brands, S.J. (comp.) 1989-2006. Systema Naturae 2000. The Taxonomicon. Universal Taxonomic Services, Amsterdam, The Netherlands. Accessed October 3, 2006.

Identifiers:

Zipcode Zoo Species Identifier: 712965

Footnotes:

Liguo Fu, Nan Li, Thomas S. Elias & Robert R. Mill "Pinaceae". in Flora of China Vol. 4 Page 11. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org.
Ronald J. Taylor "Tsuga". in Flora of North America Vol. 2. Oxford University Press. Online at EFloras.org.

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Last Revised: May 05, 2008