Rare Species Guide

  Basis for Listing

Salix pellita (satiny willow) is a tall shrub that reaches the southwestern periphery of its range in the Arrowhead Region of the state (Laurentian Mixed Forest Province). Little is known about the species in Minnesota beyond the fact that it is clearly very rare and its river bank/lakeshore habitat is increasingly threatened by human activities. In spite of extensive surveys, there are just a handful of verified records, dating back to its discovery at Lake Vermilion in northern St. Louis County by the Arthur, Bailey, Holway Expedition in 1886 (Smith 2008).

When S. pellita was listed as special concern in 1996, there were only four known records in the state, with the most recent dated 1958. The lack of data or systematic surveys prevented it from being assigned a more protective status at that time. Now, after years of targeted surveys by the Minnesota Biological Survey, only eight additional populations have been discovered in the state, and six of them occur along an 8-mile stretch of the Cloquet River. Because they are so concentrated, a single unforeseen weather event or development proposal could have a major impact on the state's population of this rare species. For these reasons, the status of S. pellita was changed to threatened in 2013.

  Description

Salix pellita is a tall shrub or sometimes a small tree, reaching a height of about 4-5 m (13-16 ft.). The bark is smooth or somewhat rough and gray. The long and narrow leaves are simple and alternate on the stem. The larger leaves are 5-12 cm (2.0-4.7 in.) long and 0.7-2 cm (0.3-0.8 in.) wide. The lower surface of the leaf has a dense covering of long straight silky hairs. The leaves are somewhat like those of S. candida (sage-leaved willow), except the hairs on the lower surface are straight and lie flat, rather than curled and tangled. The leaves of S. petiolaris (slender willow) are also similar, at least in size and shape, but are not nearly so hairy on the lower surface (Smith 2008). The flowers are borne in unisexual catkins and appear in the spring, before the leaves emerge.

  Habitat

All of the records of S. pellita to date are from sandy or rocky shores of large lakes or on banks and gravel bars of streams. The streams are generally short, with steep gradients, and the lakes occur in bedrock basins, often with rocky or bouldery shores. Salix pellita would probably not be found in swamps, marshes, or bogs. Suitable habitats must have some protection from wildfire, though they would likely be exposed to fluctuating water levels and forces such as erosion and ice scouring.

  Biology / Life History

Salix pellita produces flowers in early spring and is pollinated by insects and wind. By early summer the fruits are mature, and they release plumed seeds that can be carried by the wind for great distances. The seeds must land on a moist and exposed substrate within a few weeks if they are to germinate. Asexual reproduction has not been documented for S. pellita, though it is reasonable to expect broken twigs to be able to root on a riverbank or lakeshore, if conditions are right. Established plants, with a healthy and well-developed root system will resprout if stems are damaged by ice scouring or browsing by White-tailed Deer (Odocoileus virginianus), Moose (Alces alces), or Beaver (Castor canadensis). The roots, however, can be killed by summer (growing season) flooding, if long in duration. Also, a situation where a stagnant pool develops upstream from a beaver dam would likely suffocate the root system of S. pellita, probably within a year.

  Conservation / Management

The habitat for S. pellita occurs in a narrow band along certain streams and lakes, so any type of shoreline development or manipulation could be damaging. Shoreline stabilization techniques such as rip-rapping are extremely destructive to native habitats and the species that depend on them. Artificial structures designed to manipulate water levels, such as dams, dikes, or levees are also destructive. Beaver dams, though potentially destructive, are probably too limited in extent and duration to affect more than a portion of any given habitat. The invasion of non-native species and concentrated recreational activity are also potential concerns.

  Best Time to Search

Salix pellita can be reliably identified by characteristics of the leaves, which are fully developed by late May. The catkins can make identification easier and are present during May and June.

  Conservation Efforts in Minnesota

Although to date no specific actions have been undertaken for the conservation of this species in Minnesota, all of the known populations are on state, federal, or tribal lands. This may impart some level of protection, at least from development, and it certainly provides an opportunity for conservation measures.

  Authors/Revisions

Welby Smith (MNDNR), 2008 and 2018

(Note: all content ©MNDNR)

  References and Additional Information

Butters, F. K., and E. C. Abbe. 1953. A floristic study of Cook County, northeastern Minnesota. Rhodora 55:21-55.

Coffin, B., and L. Pfannmuller, editors. 1988. Minnesota's endangered flora and fauna. University of Minnesota Press, Minneapolis. 473 pp.

Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp.

Minnesota Department of Natural Resources, Division of Ecological Resources. 2008. Rare species guide: an online encyclopedia of Minnesota's rare native plants and animals [Web Application]. Minnesota Department of Natural Resources, St. Paul, Minnesota. Accessed 1 July 2009.

Minnesota Department of Natural Resources, Division of Fish and Wildlife. 1995. Statement of need and reasonableness in the matter of proposed amendment of Minnesota Rules, Chapter 6134: endangered and threatened species. Minnesota Department of Natural Resources, St. Paul, Minnesota. 336 pp.

Monson, P. H. 1988. Endangered, Threatened, and Special Concern plants. Grand Portage National Monument, Grand Portage, Minnesota. Olga Lakela Herbarium, University of Minnesota, Duluth. Unpublished report submitted to the National Park Service. 15 pp.

Ojakangas, R. W., and C. L. Matsch. 1982. Minnesota's geology. University of Minnesota Press, Minneapolis, Minnesota. 255 pp.

Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis. 320 pp.

Smith, W. R. 2008. Trees and shrubs of Minnesota. University of Minnesota Press, Minneapolis. 703 pp.