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Montana Field Guide

Montana Field Guides

Hybrid Crack Willow - Salix x rubens
Other Names:  Salix alba × Salix fragilis

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Non-native Species

Global Rank: GNA
State Rank: SNA

Agency Status


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General Description
Large tree up to 20 meters tall. Twigs olive to yellow-brown, brittle, easily breaking at base. Branchlets spreading, green to reddish brown, eventually glabrous. Petioles 0.5-1.5 cm long, glandular-viscid at the summit, the glands often stipitate. Leaves mostly 7-13 cm long, 1.5-3 cm wide, narrowly lanceolate to lanceolate, acuminate and often asymmetric (falcate) at tip, coarsely serrate with 4-6 glandular teeth per cm of leaf, dark to yellowish-green and shiny above, pale to white-glacous below. Catkins appearing with leaves; pistillate catkins 3-6 cm long, bracts caducous, yellowish, pubescent, apically ciliate, stamens 2. Capsules 4-5.5 mm long, narrowly conic, glabrous subsessile or stipes to 1 mm long (adapted from: Larson, 1986, Flora of the Great Plains).

Range Comments
Much of North America apart from the Southeast (Kartesz in prep. 2012).

Ornamental shade tree; rarely escaping into wet areas.

The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus vagans, Bombus bifarius, Bombus fervidus, Bombus frigidus, Bombus huntii, Bombus melanopygus, Bombus ternarius, Bombus terricola, Bombus sitkensis, Bombus occidentalis, Bombus pensylvanicus, Bombus bimaculatus, Bombus griseocollis, Bombus impatiens, and Bombus suckleyi (Plath 1934, Macior 1968, Heinrich 1976, Thorp et al. 1983, Colla and Dumesh 2010, Colla et al. 2011, Koch et al. 2012, Williams et al. 2014).


  • Literature Cited AboveLegend:   View Online Publication
    • Colla, S., L. Richardson, and P. Williams. 2011. Bumble bees of the eastern United States. Washington, DC: USDA Forest Service, Pollinator Partnership. 103 p.
    • Colla, S.R. and S. Dumesh. 2010. The bumble bees of southern Ontario: notes on natural history and distribution. Journal of the Entomological Society of Ontario 141:39-68.
    • Koch, J., J. Strange, and P. Williams. 2012. Bumble bees of the western United States. Washington, DC: USDA Forest Service, Pollinator Partnership. 143 p.
    • Macior, L.M. 1968. Bombus (Hymenoptera, Apidae) queen foraging in relation to vernal pollination in Wisconsin. Ecology 49:20-25.
    • Plath, O.E. 1934. Bumblebees and their ways. New York, NY: Macmillan Company. 201 p.
    • Thorp, R.W., D.S. Horning, and L.L. Dunning. 1983. Bumble bees and cuckoo bumble bees of California (Hymenoptera: Apidae). Bulletin of the California Insect Survey 23:1-79.
    • Williams, P., R. Thorp, L. Richardson, and S. Colla. 2014. Bumble Bees of North America. Princeton, NJ: Princeton University Press. 208 p.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Argus, G. 2010. Salix. In: Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 16+ vols. New York and Oxford. Vol. 7.
    • Dorn, R.D. 2010. The genus Salix in North America north of Mexico. 59 pp.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
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Citation for data on this website:
Hybrid Crack Willow — Salix x rubens.  Montana Field Guide.  .  Retrieved on , from