Rose family (Rosaceae)
Description: This native perennial plant is 1½–2½' tall, branching occasionally. The round stems are light green and covered with coarse spreading hairs. Both basal and cauline leaves are produced; the cauline leaves are alternate, becoming smaller as they ascend the stems. The basal and lower cauline leaves are oddly pinnate (often with 5 leaflets), while the upper cauline leaves are trifoliate or simple. The simple leaves and leaflets of the compound leaves are up to 3" long and 2½" across. They are lanceolate to ovate-oval, coarsely serrated or shallowly cleft along the margins, and largely hairless. Sometimes the leaves and leaflets are deeply cleft into 2 or 3 lobes. The terminal leaflet is larger in size than the lateral leaflets. The basal and lower cauline leaves have stout petioles, while the upper cauline leaves are nearly sessile. At the base of each petiole, there is a pair of leafy stipules that are cleft or dentate; each stipule is up to ½" long. The upper stems individually terminate in 1-3 flowers; sometimes single flowers are produced from the axils of the upper leaves. Each flower develops from a stalk (peduncle) up to 3" long; this stalk is covered with coarse spreading hairs. Each flower is about ½" across, consisting of 5 petals that are white or cream, 5 triangular green sepals, and several stamens surrounding a large cluster of green carpels with elongated styles. The petals are shorter than the sepals. The anthers are usually dull yellow or tan. The receptacle of the flower (underneath the carpels) is hairless or nearly so. The blooming period occurs from late spring to mid-summer and lasts about a month. There is no noticeable floral scent. Each flower is replaced by a spheroid cluster of achenes with elongated styles that are hooked at their tips. This fruiting cluster is about ¾" across; it is initially green, but eventually turns brown. The root system consists of a taproot and rhizomes; vegetative offsets are often formed.
Cultivation: The preference is partial sun, moist to mesic conditions, and soil containing loam or sandy loam. Full sun and light shade are also tolerated.
Range & Habitat: Rough Avens occurs occasionally in central and northern Illinois, but it is absent from the southern and southwestern areas of the state (see Distribution Map). Habitats include savannas, thickets, woodland borders, and moist meadows. Sometimes it is found in thickets and prairie remnants along railroads and roadsides.
Faunal Associations: Information about floral-faunal relationships for this species is rather limited. They are probably similar to those of Geum canadense (White Avens). The nectar and pollen of the flowers probably attract small bees, wasps, and flies. Insects that feed on the foliage of Geum spp. (Avens) include the aphids Acyrthosiphon pseudodirhodum, Macrosiphum gei, Macrosiphum pallidum, and Macrosiphum pseudorosae. In addition, larvae of a moth, Tinagma obscurofasciella, mine the leaves. The achenes with hooked styles can cling to the fur of mammals, feathers of birds, and clothing of humans; by this means, they can be distributed across considerable distances.
Photographic Location: Between a thicket and prairie remnant along a railroad in Champaign County, Illinois.
Comments: Rough Avens blooms a little later than Geum vernum (Spring Avens), but a little earlier than Geum canadense (White Avens) and Geum virginianum (Pale Avens). It can be confused with White Avens. However, Rough Avens has petals that are shorter than the sepals and its flowering stalks have coarse spreading hairs. White Avens has petals that are as long or longer than the sepals and its flowering stalks are finely pubescent. Pale Avens also has an appearance that is similar to Rough Avens; it is restricted to southern Illinois. Pale Avens has slightly smaller flowers (about 1/3" across) with cream petals that are much shorter than the sepals. The receptacles of its flowers are bristly-hairy, while the receptacles of Rough Avens are hairless or nearly so.