Rudbeckia subtomentosa (Sweet Coneflower)

Plant Info
Also known as: Sweet Black-eyed Susan
Genus:Rudbeckia
Family:Asteraceae (Aster)
Life cycle:perennial
Origin:native
Habitat:part shade, sun; sandy, loamy, moist soil; wet to mesic prairie, steam banks, woodland openings and edges
Bloom season:July - October
Plant height:2 to 6 feet
Wetland Indicator Status:GP: FAC MW: FACU NCNE: FACU
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 7+petals Cluster type: panicle

[photo of flowers] 8 to 25 flower heads at the top of the plant, single at the tips of long stalks and the tips of branching stems. Flowers are 2 to 3 inches across with 10 to 16 yellow petals (ray flowers) that are sparsely hairy and gland-dotted on the underside. The center disk is a purplish-brown, dome-shaped to hemispheric, and covered in up to 400 tiny dark purplish-brown flowers that bloom from the bottom of the disk up. The bracts surrounding the base of the flower are hairy, gland-dotted, unequal in size, lance to egg-shaped with a sharply pointed tip, and the inner bracts smaller than the outer. Flower stalks are ribbed and densely covered in short, ascending hairs.

Leaves and stems: Leaf attachment: alternate Leaf type: lobed Leaf type: simple

[photo of lobed leaf] Leaves are gland dotted and rough-hairy, especially on the underside and along major veins. Lower and basal leaves are up to 8 inches long and 4 inches wide with 3 to 5 lance-elliptic lobes, coarsely toothed around the lobe edges, and stalked.

[photo of upper stem leaves] Mid and upper stem leaves are smaller, unlobed and more egg-shaped, short-stalked to stalkless, sparsely toothed to toothless, rounded to wedge-shaped at the base and pointed at the tip. Stems are branched, mostly erect, ridged, densely short hairy in the upper plant and typically hairless or nearly so near the base.

Fruit: Fruit type: seed without plume

The center disk becomes a head of dark, 4-sided seeds that lack a tuft of hairs.

Notes:

Sweet Coneflower has only been recorded once in Minnesota, in Mower County near the Iowa border, putting Minnesota at the extreme northern tip of its range. The flowers are similar to the related and much more common Black-eyed Susan (Rudbeckia hirta), which is easily distinguished by its long spreading hairs and unbranched or few-branched habit. The mix of lobed and unlobed leaves is shared with Brown-eyed Susan (Rudbeckia triloba), which has smaller flowers and a proportionately larger center disk. Sweet Coneflower is occasionally available in the nursery trade and is a personal favorite Rudbeckia species for the home garden.

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More photos

Photos courtesy Peter M. Dziuk taken in private gardens in Anoka and Ramsey counties.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Shannon - Wright County
on: 2015-09-01 10:17:38

pretty sure these are growing in Colinwood Park. Photographed some in July 2015 walking the prairie trail.

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