- Scientific name: Equisetum scirpoides Michx.
- Species of Greatest Conservation Need (MA State Wildlife Action Plan)
- Special Concern (MA Endangered Species Act)
Description
Dwarf scouring rush, Equisetum scirpoides, is a member of the horsetail family (Equisetaceae). It is 10-20 cm (4-8 in) tall, evergreen and appears as a dark tuft of wiry stems. Dwarf scouring rush has slender stems which may curve upward or lie flat along the ground and widely branching rhizomes. The stem has 3 to 4 broad and deeply concave ridges. Triangular sheaths surrounding the stems are 3-4 mm (<1 in) long and have 3 or 4 teeth. Small (3-5mm [0.12-0.2 in]), dark cones develop in late summer."
Life cycle and behavior
Dwarf Scouring rush is a perennial plant. Its many stems are connected with an underground rhizome, which produce both fertile and non-fertile stems. Fertile ramets tend to be a bit straighter than the non-fertile ones. Mature fruit (spores) may be found in late summer (Native Plant Trust 2014).
Population status
Dwarf scouring rush is listed under the Massachusetts Endangered Species Act as a species of special concern. 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.
Thirty-four populations of dwarf scouring rush have been verified as extant since 1999 in Berkshire, Franklin and Hampshire Counties. Six additional populations have not been recently relocated.
Distribution in Massachusetts. 1999-2024. Based on records in the Natural Heritage Database.
Distribution and abundance
Dwarf scouring rush has a circumboreal distribution. In North America, it extends across Canada and south into Connecticut, west through Illinois, Iowa, South Dakota, and Wyoming and then into Washington.
In New England, dwarf scouring rush is critically imperiled in Connecticut, vulnerable in Massachusetts, secure in Vermont, and not ranked in Maine and New Hampshire. It is not known to occur in Rhode Island.
Thirty-four populations of dwarf scouring rush have been verified as extant since 1999 in Berkshire, Franklin and Hampshire Counties. Six additional populations have not been recently relocated. One reason for its rarity in Massachusetts is because it is near the southern edge of its range. It is considered rare in most of the states on the southern edge of its distribution. Globally, NatureServe ranks dwarf scouring rush as G5, secure.
Habitat
Dwarf scouring rush is found on moist banks and seepy wooded slopes and hillsides with springs and streams: they are often in ecotones between upland and wetland sites. Dwarf scouring rush is known to grow in subacidic and acid glacially derived soil. Associated species often include tree elements of the northern hardwood forest including red maple (Acer rubrum), sugar maple (A. saccharum), white ash (Fraxinus americana), eastern hemlock (Tsuga canadensis), and yellow birch (Betula alleghaniensis). The hemlock provides shade and a cool habitat. Shrubs may include striped maple (Acer pensylvanica), spicebush (Lindera benzoin), and low raspberry (Rubus pubescens). The herbaceous layer may be sparse. However, a variety of species, including repeated occurrences of non-natives, have been reported in the area of dwarf scouring rush populations: including cinnamon fern (Osmunda cinnamomea), small Enchanter’s nightshade (Circaea alpina), Colt’s foot (Tussilago farfara), tree seedlings, other horsetails, and liverworts and mosses.
Healthy habitats are vital for supporting native wildlife and plants. Explore habitats and learn about conservation and restoration in Massachusetts.
Threats
Invasive species are the primary threat to this species.
Conservation
Most of the occurrences of dwarf scouring rush have invasive species near the population. Competition from non-native invasive species can be a threat through shading and loss of space for the native species. Monitoring and removal of competing vegetation should be considered as a management strategy where appropriate. An additional likely problem in many populations is that the hemlock overstory may be damaged and thinned by wooly adelgids, another invasive species that infects and kills hemlock trees. 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.
Several of the populations of dwarf scouring rush are near roads: widening of roads and creation, formal and informal, of pull-off sites should be reviewed with regard to the effects on the dwarf scouring rush.
Contact
| Date published: | May 7, 2025 |
|---|