Symphyotrichum urophyllum (Arrowleaf Aster)
|Also known as:||White Arrow-leaved Aster, Tail-leaved Aster|
|Habitat:||part shade, sun; dry to average sandy or rocky soil; open woods, woodland edges, savanna, glades, grassy railroads, bluffs|
|Bloom season:||August - October|
|Plant height:||1 to 4 feet|
|Wetland Indicator Status:||none|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Branching cluster of numerous, short-stalked, daisy-type flowers at the top of the plant and arising from upper leaf axils. The cluster is taller than wide with branches erect to ascending and often take on a cylindrical shape from the tightly packed flowers. Flowers are ½ to ¾ inch across with 8 to 15 petals (ray flowers) surrounding a pale yellow center disk that turns reddish with age. Ray color is typically white, occasionally pale blue.
Surrounding the base of the flower are 4 to 6 layers of sharply pointed bracts (phyllaries), the outer awl-shaped, the inner lance-linear, pale green to whitish at the base with long, slender green to purplish tips that mostly flare out. Phyllaries are hairless except sometimes for minute hairs around the tip edge. Flower stalks are typically under ¾ inch long with a few, small, leaf-like bracts and may be sparsely hairy.
Leaves and stems:
Leaves are thin, 1 to 4½ inches long, ½ to 2 inches wide, pointed at the tip, usually shallowly toothed around the edges, the upper surface smooth to sparsely hairy to rough textured, softly hairy on the underside especially along the midvein. Basal and lowest stem leaves are narrowly heart-shaped, on long stalks that are sometimes narrowly winged. Basal and the lowest stem leaves typically wither away by flowering time but may persist.
Leaves become less heart-shaped and more egg-shaped to lance-linear as they ascend the stem, with shorter, more broadly winged stalks. The uppermost leaves are often stalkless, may be toothless and are reduced to bracts in the flower clusters. Stems are single or multiple from the base, mostly erect, unbranched except in the flower clusters, typically smooth near the base and sparsely hairy in the upper plant.
Fruit is a dry seed with a tuft of white hairs to carry it off in the wind.
The leaves of Arrowleaf Aster distinguish it from other asters with small, white flowers. While there are several other asters with heart-shaped leaves, the others have blue to violet flowers in more open panicles and broader phyllaries that are appressed, not flaring out.
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- Arrowleaf Aster plants
- Arrowleaf Aster plants
- flowering branches starting to bloom
- crowded, cylindrical clusters
Photos by K. Chayka taken at Sucker Lake, Ramsey County, and Murphy-Hanrehan Park Reserve, Scott County. Other photos by Peter M. Dziuk.
Have you seen this plant in Minnesota, or have any other comments about it?