Autumn Willow - Salix serissima
State Rank Reason (see State Rank above)
This willow is primarily found in Montana along the Rocky Mountain Front. Approximately half the occurrences are on lands managed in part for their conservation value. The species is primarily susceptible to impacts associated with heavy grazing and changes in the hydrology of the fens and wet meadows which it occupies.
Autumn Willow is a deciduous shrub growing up to 3 m tall, with bark ranging from grey on the older branches to straw colored on younger branches to shiny red-brown on the youngest twigs. Buds and leaves are arranged alternately on the stems. The leaf petioles usually have glands just below the leaf blades. The elliptic to lance-shaped leaf blades are 4-8 cm long and 1-2.5 cm wide and have long, tapered tips and fine glandular-tipped teeth on the margins; they are semi-glossy yellow-green to dark green above and dull and paler colored below. Flowers are borne in catkins which appear after the leaves; male and female flowers are borne on separate plants. The female catkins are 2-4 cm long and are borne on short, leafy branchlets. The bracts which subtend the female flowers are light yellow and hairy and fall off before the capsules mature. The capsules lack hairs and are 7-10 mm long and borne on stalks which are 0.5-2 mm long.
Flowering in June, fruiting in July-September.
Distinguishing characteristics include the finely-toothed, long taper-tipped, bicolored leaves with glandular petioles and the glabrous capsules which mature later than those of most other Montana willows.
NT to NL south to CO, SD, IN and NJ (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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(Observations spanning multiple months or years are excluded from time charts)
Fens and swamps in the valley and foothill zones.
Ecological Systems Associated with this Species
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).
Threats or Limiting Factors
STATE THREAT SCORE REASON
Reported threats to Montana's populations of Autumn Willow are currently assigned as unknown (MTNHP Threat Assessment 2021). Hydrologic alteration has likely destroyed one population where an impoundment was placed. Information about the likelihood of this threat to impact populations in the future is needed to assess its relative risk. Livestock trampling and grazing is also indicated to threaten populations, but impacts were reported to occur over timeframe exceeding 10 years. Information about expected impacts found in a 10-year timeframe are needed to assess relative risk to populations.
- 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.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 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. 1970. The Willows of Montana. Montana State University Herbarium, Dept. of Botany and Microbiology, Bozeman, Montana. 18 pp.
- Dorn, R.D. 2010. The genus Salix in North America north of Mexico. 59 pp.
- 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.
- Little, E.L., Jr. 1979. Checklist of United States trees (native and naturalized). Agriculture Handbook No. 541. U.S. Forest Service, Washington, D.C. 375 pp.