This perennial wildflower consists of a rosette of basal leaves
spanning ½-1' across and a more or less erect flowering stalk about
¾-2' 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 ¾-2½"
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 ½-¾" across. Each flowerhead has 8-16 ray florets
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.
The preference is moist to dry-mesic conditions, full to partial
sunlight, and soil containing loam, sand, or rocky material.
The native Round-Leaved Ragwort is
Illinois and scattered areas elsewhere within the state, where
is rare (see Distribution
). 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.
The nectar and pollen of the flowerheads
Cuckoo bees (Nomada spp.
Halictid bees (Augochlorella
), Andrenid bees (Andrena
), Syrphid flies,
Tachinid flies, and miscellaneous beetles. One bee species, Andrena
, is a specialist pollinator (oligolege) of Senecio spp.
(ragworts). Another insect, Neacoryphus
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
although sheep are more tolerant of it (Georgia, 1913).
A wildflower garden at Kitty Todd
Preserve in NW Ohio.
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
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
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.