Prairie Smoke
Geum triflorum
Rose family (Rosaceae)

Description: This perennial wildflower forms a low leafy rosette about 6-10" across. Individual basal leaves are 3-5" long and 1-1" across; each leaf is odd-pinnate with 3-6 pairs of lateral leaflets and a terminal leaflet. There are also secondary leaflets that are inserted between some pairs of lateral leaflets; these secondary leaflets are quite small and poorly developed. These leaflets are oriented away from the center of the rosette, forming an oblique angle with the rachis (central stalk of the compound leaf). Individual leaflets are oblanceolate in shape, shallowly cleft, coarsely dentate, and slightly ciliate along their margins; they are somewhat variable and irregular. During the growing season, the upper leaf surface is medium green and sparsely covered with short appressed hairs, while the lower leaf surface is light green and hairy primarily along the rachis and major veins.



Flowering stalks develop from the center of the rosette, becoming 5-10" tall at maturity. Each stalk terminates in an umbel of 3 nodding flowers. The flowering stalks (peduncles) are reddish green to reddish purple, terete, and densely hairy. There is a pair of leafy bracts at the base of each umbel that are deeply cleft with linear to linear-oblong segments. These bracts are reddish green to reddish purple and hairy. Sometimes pairs of leafy bractlets develop along the hairy pedicels of the flowers; these bractlets are also deeply cleft with linear segments. Individual flowers are -1" long and similarly across. Each flower consists of 5 pale red to purplish red sepals, 5 white to pale red petals, a central cluster of pistils, and numerous stamens that are arranged in a ring. The sepals extend along the entire length of the flower and they are joined together at the base; each sepal is deltate in shape and hairy. Each flower also has 5 linear floral bracts (one floral bract between each adjacent pair of sepals).
These floral bracts are the same color as the sepals and hairy; they extend outward from the sepals. The petals are largely hidden by the long sepals as the flower barely opens. The blooming period can occur from early to late spring and lasts about 1-2 months. Afterwards, each flower becomes erect and develops a dense cluster of achenes with long feathery tails. These achenes are distributed by the wind. The root system is fibrous and rhizomatous. This wildflower can form small clonal colonies of plants from the rhizomes. A rosette of low basal leaves persists through the winter; these winter leaves are often reddish purple.

Cultivation: The preference is full sun, mesic to dry conditions, and a barren soil that is rocky, gravelly, or sandy. Young plants should be kept well-watered during hot summer weather as Prairie Smoke is adapted to a somewhat cool northern climate. Competition from taller and more aggressive plants is not tolerated.

Range & Habitat: The native Prairie Smoke is restricted to northern Illinois, where it is uncommon. Elsewhere in the state, it is absent. In Illinois, habitats consist of dry gravelly prairies and hill prairies. In other states (e.g., Michigan), this plant has been found in sand prairies and alvars (a habitat that is dominated by limestone slabs). This conservative species is found in high quality prairies where the vegetation is neither too dense nor tall.

Faunal Associations: The flowers are cross-pollinated by bumblebees, which seek primarily nectar from the flowers (personal observation, 2011; Choberka et al., 2000). These insects are strong enough to force their way into the flowers. The adults of a leaf beetle, Graphops marcassita, have been observed to feed on Prairie Smoke (Clark et al., 2004). The larvae of this beetle may also feed on the roots.

Photographic Location: The wildflower garden of the webmaster in Urbana, Illinois.



Comments:
Prairie Smoke is an attractive little plant that should be cultivated more often. The reddish flowers remain attractive for 2-3 months during both the blooming period and afterwards as the achenes develop. It is an easy plant to identify because no other Geum sp. (Avens) within Illinois develops achenes with long feathery tails. Only one other species in this genus, Geum rivale (Water Avens), also produces large reddish flowers. However, Water Avens prefers much wetter habitats than Prairie Smoke. Within the state, other species in this genus produce more conventional flowers with 5 spreading petals that are white or yellow.


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