- Scientific name: Betula pumila L.
- Species of Greatest Conservation Need (MA State Wildlife Action Plan)
- Endangered (MA Endangered Species Act)
Description
Photo credit: Bruce Sorrie
Swamp birch – also known as dwarf birch, bog birch, or low birch – is a medium-sized, bushy shrub in the birch family (Betulaceae) that sometimes attains a height of 4 m (13 ft). Its bark is brown, and its young leaves are covered with soft white hairs. Young twigs may also be hairy. The 2-3 cm (0.8-1.2 in) long leaves are coarsely toothed and egg-shaped, with the broader ends at the tops. They are lighter in color below. The unisexual catkins first appear in the fall; the erect, female catkins measure from 1-2 cm (0.4-0.8 in) long. The winged, scale-like nutlets mature from late June to late September and are called samaras.
Population status
Swamp birch. Photo credit: Robert Wernerehl
Swamp birch is listed under the Massachusetts Endangered Species Act as endangered. All listed species are protected from killing, collecting, possessing, or sale and from activities that would destroy habitat and thus directly or indirectly cause mortality or disrupt critical behaviors. There have been 4 populations that have been verified since 1999 in Berkshire County. One population, also from Berkshire County, has not been relocated in the past 25 years.
Distribution and abundance
The range of swamp birch extends across the northern half of North America, except for Alaska, Rhode Island, and Vermont. It extends south to New Jersey west to Kansas and Colorado to Oregon. In New England, it is considered critically imperiled in Massachusetts and New Hampshire, and imperiled in Connecticut and Maine.
Distribution in Massachusetts
1999-2024
Based on records in the Natural Heritage Database
Habitat
Swamp birch is generally a calciphile. It is found in open and forested wetlands influenced by calcareous groundwater seepage. Specific habitats in the Commonwealth include a shrub-dominated peaty wetland that is fed by calcareous seepage, a larch bog, and calcareous fens.Associated species include speckled alder (Alnus rugosa), larch (Larix laricina), shrubby cinquefoil (Dasiphora floribunda), tussock sedge (Carex stricta) and hoary willow (Salix candida).
Healthy habitats are vital for supporting native wildlife and plants. Explore habitats and learn about conservation and restoration in Massachusetts.
Threats
Reasons for its rarity in Massachusetts include a scarcity of alkaline habitats and habitat destruction. Threats include degradation of habitat and the raising of water levels by beaver activity. Observations of populations in Massachusetts seem to indicate that beavers can raise water levels to the point that swamp birch populations will die back.
Conservation and management
Research needs
Competition from phragmites (Phragmites australis) can be a real threat to swamp birch on disturbed habitats. Monitoring and removal of competing vegetation should be considered as a management strategy where appropriate. All active management of rare plant populations (including invasive species removal) is subject to review under the Massachusetts Endangered Species Act and should be planned in close consultation with the MassWildlife’s Natural Heritage & Endangered Species Program.
Contact
| Date published: | April 7, 2025 |
|---|