IUCN threat status:

Not evaluated

Comprehensive Description

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Description

This plant is a summer annual about 1-4½' tall, branching occasionally. The stems are light green to purple, more or less terete, and glabrous. Leaves are usually opposite, although some of the uppermost leaves may be alternate. The leaf blades are 2-6" long and ½-1½" across; they are lanceolate to oblong-lanceolate and coarsely serrated along their margins; some of the lower leaves often have 1-2 smaller basal lobes. The upper blade surface is medium green and glabrous, while the lower blade surface is pale-medium green and glabrous. During the autumn, the leaf blades often become purplish green or purple. The petioles are up to 2" long and usually narrow, although some of them may be partially winged. The upper stems terminate in 1-3 flowerheads each on peduncles about ½-4" long. The peduncles are light green or purplish green, more or less terete, and glabrous. Each flowerhead spans ½-1¼" across (excluding the leafy bracts), consisting of numerous disk florets and usually no ray florets. When ray florets occur, they are insignificant and few in number. The corollas of the disk florets are yellow to orange, narrowly tubular in shape, and about 3 mm. (1/8") long; each corolla has 4-5 recurved to ascending lobes along its upper rim. The disk florets are perfect, while the ray florets, if they are present, are sterile. Surrounding the disk florets are about 8 floral bracts (phyllaries) that are yellowish brown or yellowish black, ovate in shape, and glabrous; they are about 6 mm. (¼") long. Originating from below both the disk florets and floral bracts, but spreading outward, there are 3-8 leafy bracts about ½-1½" long. The leafy bracts are green, glabrous, and oblanceolate, elliptic, or oblong in shape. The blooming period occurs from late summer into the fall, lasting about 1-2 months. The disk florets are replaced by awned achenes that are about 5-6 mm. in length (excluding the awns), oblanceolate in shape, and somewhat flattened. At the apex of each achene, there are 4 barbed awns consisting of two longer outer awns (about 4 mm. in length) and two shorter inner awns (about 2 mm. in length). However, because the 2 inner awns are fragile and often become detached, some achenes will have only 2-3 awns (or even less, should the outer awns become detached). The root system consists of a shallow branching taproot. This plant reproduces by reseeding itself, occasionally forming colonies.

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Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© John Hilty

Source: Illinois Wildflowers

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