Skip to main content

Prairie ironweed

Vernonia fasciculata Michx.

Images

Click on image to view full size

Prairie ironweed leaves
Prairie ironweed
Prairie ironweed inflorescence

Morphology

Stem
Erect, simple proximally, branched distally, glabrous or minutely pubescent.
Leaves
Alternate, mostly cauline, simple; petiole present or absent; blade linear to lanceolate, 2 to 5.6 inches long, .16 to 1.8 inches wide, base attenuate or long-tapered, margins serrate, apex attenuate or acuminate, abaxial surface glabrous and conspicuously gland-dotted, adaxial surface glabrous or sparsely puberulent and gland-dotted.
Inflorescence
Heads in congested corymb-like arrays: peduncles .04 to .5 inch. Involucres narrowly campanulate, .16 to .35 inch. Phyllaries 25-35 in 4-5 series, ovate, to oblong-ovate, .12 to .28 inch, apex rounded to acute, appressed.
Flower
Ray florets 0; disc florets 12-25; corolla reddish purple, .35 to .5 inch.
Fruit
Achenes brown to gray, elongate-ellipsoid, .12 to .16 inch, 8-10-ribbed, glabrous or strigulose, often gland-dotted; pappus of brown to purplish brown scales or bristles in 2 series, outer 20-30 short scales, .02 to .12 inch, inner 20-40 long bristles, .2 to .28 inch.

Ecology

Habitat
Mesic tallgrass prairies, wetlands, ditches
Distribution
East 2/3 of Kansas

Additional Notes

Comments

Vernonia,for William Vernon, English botanist and fasciculata, bunched, alluding to the crowded heads. Subspecies of Vernonia fasciculata intergrade over a large area of the western Midwest and southeastern Great Plains. Subsp. corymbose (Schwein.) S. B. Jones, the typical expression in the northern Great Plains, is confined in Kansas to wetlands in the central part of the state, especially in Barton, Reno, Rice, and Stafford counties. It has middle cauline leaf blade ovate-lanceolate, 1.5 to 4 inches, and margins scabrous adaxially. Subsp. fasciculata occurs in the eastern 1/5 of Kansas, with scattered populations encountered westward. It has middle cauline leaf blades narrowly to broadly lanceolate, 3 to 7 inches, and margins glabrous or minutely puberulent adaxially.

Quick Facts
Plant Type
Wildflower
Family
Asteraceae – Sunflower Family
Life Span
Perennial
Height
12-48 inches
Origin
Native
Last Updated
2021-11-07
Color Groups
Blue, Purple, Lavender & Violet Wildflowers
Flowering Period
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Blooms: July, August, September