Endangered Plants of Ontario

Prairie Smoke

Geum triflorum

Status

Uncommon in Ontario; extirpated from New York; threatened in Michigan.

Range

Ontario west to British Columbia, south to northern Illinois and California

Habitat

Dry prairies and other dry, open sites; in Ontario generally in full sun in alvars.

Height

20 to 40 cm

Bloom Period

May and June

Factors contributing to its status

As its name suggests, this is primarily a prairie species that reaches reaches the eastern limits of its range in Ontario.

East of the prairies, it is largely restricted to an unusual habitat called an alvar, where there is only a shallow layer of soil over flat limestone rock. Some Ontario populations are quite large, but they are few and widely scattered. Although major destruction of the habitat would obviously be detrimental to this species, some disturbance is generally essential for perpetuationof alvars. Otherwise, soil accumulation would eventually permit the development of trees and shrubs that would shade out teh characteristic, often rare, alvar plants.

Notes

Prairie smoke has small, pale orange petals almost concealed by the maroon sepals. Other, more abundant species of Geum in Ontario, known by the common name avens, have spreading, yellow or white petals and small, green sepals. The seeds of these woodland and roadside species are dispersed by hooks that cling to animal fur and human clothing. Prairie smoke, in constrast, is dispersed by wind. The seeds, with their feathery plumes, are blown unimpeded across open, dry prairie and alvar habitats.

Prairie smoke encounters exrremes of wetness and dryness in alvars. Because teh bedrock below the thin layer of soil impedes drainage, the soil remains saturated for a time after a rain or after snow melt in the spring. Soon, however, the shallow osil becomes very dry, further stressing the plants. This dryness is a major factor limiting growth in this habitat, especially as the bedrock prevents plants from developing deep root systems.

Habitat	Dry prairies and other dry, open sites; in Ontario generally in full sun in alvars.
Height	20 to 40 cm
Bloom Period	May and June
Factors contributing to its status	As its name suggests, this is primarily a prairie species that reaches reaches the eastern limits of its range in Ontario. East of the prairies, it is largely restricted to an unusual habitat called an alvar, where there is only a shallow layer of soil over flat limestone rock. Some Ontario populations are quite large, but they are few and widely scattered. Although major destruction of the habitat would obviously be detrimental to this species, some disturbance is generally essential for perpetuationof alvars. Otherwise, soil accumulation would eventually permit the development of trees and shrubs that would shade out teh characteristic, often rare, alvar plants.
Notes	Prairie smoke has small, pale orange petals almost concealed by the maroon sepals. Other, more abundant species of Geum in Ontario, known by the common name avens, have spreading, yellow or white petals and small, green sepals. The seeds of these woodland and roadside species are dispersed by hooks that cling to animal fur and human clothing. Prairie smoke, in constrast, is dispersed by wind. The seeds, with their feathery plumes, are blown unimpeded across open, dry prairie and alvar habitats. Prairie smoke encounters exrremes of wetness and dryness in alvars. Because teh bedrock below the thin layer of soil impedes drainage, the soil remains saturated for a time after a rain or after snow melt in the spring. Soon, however, the shallow osil becomes very dry, further stressing the plants. This dryness is a major factor limiting growth in this habitat, especially as the bedrock prevents plants from developing deep root systems.