Round-Leaved Ragwort
Senecio obovatus
Aster family (Asteraceae)

Description: This perennial wildflower consists of a rosette of basal leaves spanning -1' across and a more or less erect flowering stalk about -2' tall. The basal leaves are 3-6" long (including the petioles). The leaf blades are oval, obovate, or orbicular in shape with dentate-crenate margins; they are medium green and glabrous. The petioles are light green to dull purple and as long as the blades; sometimes they are slightly winged and/or cobwebby-pubescent. The flowering stalk is light green to dull purple and terete; it may have some cobwebby pubescence toward the base, otherwise it is glabrous. About 2-3 alternate leaves occur along the stalk that are up -2" long; they are usually elliptic-pinnatifid or oblong-pinnatifid in shape with ragged lobes. The stalk terminates in a flat-headed panicle (or compound corymb) of flowerheads. Individual flowerheads are -" across. Each flowerhead has 8-16 ray florets that surround numerous disk florets in the center. The petaloid extensions of the ray florets are yellow, while the disk florets are orange-yellow. At the base of each flowerhead, there are light green bracts (phyllaries) in a single series that are linear-lanceolate. The blooming period occurs during late spring and lasts about 3 weeks. During the summer, both ray and disk florets are replaced by bullet-shaped achenes (about 2-3 mm. in length) with tufts of white hair. The achenes are distributed by the wind. The root system is fibrous, producing vegetative offsets from either rhizomes or stolons. At favorable sites, small colonies of plants occasionally develop.



Cultivation:
The preference is moist to dry-mesic conditions, full to partial sunlight, and soil containing loam, sand, or rocky material.

Range & Habitat: The native Round-Leaved Ragwort is found in east-central Illinois and scattered areas elsewhere within the state, where it is rare (see Distribution Map). Illinois lies along the western range-limit for this species; it is more common further to the east. Habitats include rocky upland woodlands, edges of bluffs, limestone glades, loamy savannas, and sandy savannas. Occasional disturbance is beneficial if it reduces competition from woody vegetation.

Faunal Associations: The nectar and pollen of the flowerheads attract Cuckoo bees (Nomada spp.), Halictid bees (Augochlorella spp., Halictus spp., Lasioglossum spp.), Andrenid bees (Andrena spp.), Syrphid flies, Tachinid flies, and miscellaneous beetles. One bee species, Andrena gardineri, is a specialist pollinator (oligolege) of Senecio spp. (ragworts). Another insect, Neacoryphus bicrucis (White-Crossed Seed Bug), feeds on the seeds of these plants, while the caterpillars of an uncommon butterfly, Calephelis borealis (Northern Metalmark), feed on the foliage of Round-Leaved Ragwort in particular. The foliage of this and other ragworts is toxic to many mammalian herbivores, although sheep are more tolerant of it (Georgia, 1913).



Photographic Location:
A wildflower garden at Kitty Todd Nature Preserve in NW Ohio.

Comments: The different species of ragwort are distinguished from each other by the shape of their basal leaves and hairiness of individual plants. Round-Leaved Ragwort resembles Golden Ragwort (Senecio aureus), except its leaves are not indented (cordate) where the petioles join the blades. It is also more likely to have narrowly winged petioles than the latter species. Round-Leaved Ragwort also resembles Prairie Ragwort (Senecio plattensis), except it lacks the abundant cobwebby and mealy hairs of the latter during the blooming period. Round-Leaved Ragwort often has some cobwebby hairs toward the base of its stems and along its petioles, but not to the same extent as Prairie Ragwort. In addition, plants of the latter species are usually smaller in size.

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