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White avens blooms slightly later than rough avens (Geum laciniatum); it reaches about the same size (1.5-2.5' tall). The flowers are 1/2" diameter; they have five green sepals that are white-edged, pointed, and the same length or (usually) shorter than the petals; five white, rounded petals with a narrow attachment; and numerous (25-120) stamens surrounding a dome-shaped mass of green styles about a third the diameter of flower. The sepals initially lie under the petals but later become reflexed back parallel to the flower peduncle.The spherical fruit is covered with long, hooked spines (actually, persistant styles) that help the seeds stick to fur and clothing. White avens is distinguished from rough avens (G. lacinatum) by their flower stalks covered with short, fine hairs (rather than long, coarse hairs) and sepals that are shorter than the petals.

Geum

Geum canadense

white avens [Blooms: Jun-Jul]

Rough avens flowers are 1/2" wide, with five triangular green sepals longer than the petals, five cream or white, circular petals with narrow attachments, and numerous (25-120) stamens with (initially) cream-colored anthers distributed around a central gumdrop-shaped mound of green carpels with long styles. The fruit is more or less spheroid, 3/4" across, and covered with long, hooked spines (actually, persistant styles) that help the seeds attach to clothing and animal fur. Note that some sources identify this species as Geum virginianum, but G. virginianum is the cream avens according to the USDA Plants database; Hilty (ILW) lists G. virginianum as "restricted to southern Illinois". The two species are very similar, but G. lacinatum has very hairy stems and hairless receptacles and G. virginianum has smaller flowers (1/3") with cream-colored petals dwarfed by the sepals. Rough avens is distinguished from white avens (G. canadense, also found in Jackson Park) by petals that are shorter than the sepals and their very hairy flower stalks; rough avens also blooms earlier than whte avens.

Geum

Geum laciniatum

rough avens [Blooms: June]

Prairie smoke leaves, stems, and the exterior of the flowers are densely hairy. Reddish-green or -purple flowering stalks arise from the center of the leaf rosette; they produce three buds at their apex which develop into three nodding flowers (as implied by the species name) with a pair of bracts at the base of the triplet that are divided into narrow strips as if cut with scissors. Each flower is 3/4-1" in both dimensions; five triangular red to reddish-purple sepals hide almost all the remainder of the flower, covering all of the five white or reddish petals except their tips, a ring of stamens, and a central cluster of pistils. The opening to the interior of the flower is highly constricted. A spreading, narrow floral bract identical in color to the sepals lies between each pair of sepals (for a total of five). After fertilization (by bumblebees), the flower peduncle straightens so the flower points straight up. A dense cluster of seeds attached to 2" long, feathery plumes (the "smoke") transform the appearance of the flower; the seeds are later dispersed by the wind. Frustrated bumblebees unable to force their way into flowers (and some wasps and beetles) may occasionally chew their way through the sepals and petals near the base of the flower to access the nectar. No other avens (Geum sp.) in Illinois produces seeds with feathery plumes; prairie smoke's closest relatives in Jackson Park, whte avens and rough avens, look nothing like it.

Geum

Geum triflorum

prairie smoke [Blooms: Apr-Jun]