Here is a tall, erect aster that prefers moist, sunny areas and features a starry display of purplish flowers in late summer and early fall. Swamp aster is found around the Great Lakes and other cool, moist areas, and it performs best when it’s sited in moist, or even boggy, conditions. However, it doesn’t tolerate standing water. The size of individual plants can be highly variable, ranging from 1½ to 6 feet in height. It doesn’t bloom until August through October, so don’t mistake it for a weed and pull it out. It flowers abundantly in loose, open panicles of violet-to-lavender or white daisy-like flowers with yellow centers. Its glossy, narrow leaves attach to reddish-purple stems, giving rise to the common names “glossy-leaved aster” and “purple-stem aster.” Because the leaves tend to wither or become battered looking by the end of the year, it’s often recommended to plant asters in the rear of gardens so that lower plants can hide the missing lower leaves or leaves dessicated by mildew. Swamp aster has an appearance similar to New England aster, but the former tends to have longer leaves, fewer ray florets, stiff rather than soft hairs, and a lighter purple color.
Because it blooms in early fall, swamp aster is a critical food source for over 100 species of bees, flies, wasps, moths, butterflies, and beetles. Bumble bee queens and monarchs are often found on asters as they stock up on energy before hibernating and migrating, respectively.
Native habitats include stream and river banks, open swamps, bogs, ditches, sedge meadows, and other wetlands. Swamp aster pairs well with goldenrod, dense blazing star, and blue vervain. It’s an excellent plant for rain gardens, pond borders and stream banks, the rear of mixed beds, moist meadows, and naturalized and butterfly gardens.
Plant Characteristics:
Grows 1 ½-6’ tall and 2-3’ wide. Occasionally reaches 8’.
Prefers full sun and tolerates part shade.
Prefers wet-to-moist, fertile soils but also grows well in well-drained, average soils. It doesn’t tolerate standing water or dry, sandy soils.
Panicles of flower heads at the ends of stems and one-inch stalks have 30-50 ray florets about an inch across that are lavender to purple and occasionally white. Rays are very long and slender. The central disk florets are five-lobed and turn from yellow to red. The flowers bloom from late summer into fall for about two months. Florets give way to bullet-shaped achenes with small tufts of white hair for wind dispersal.
Narrow, lance-shaped leaves are up to 6” long, becoming gradually smaller as they ascend. They have a bristly texture and a line of hairs on the underside. Basal and lower-stem leaves tend to wither by the time flowers appear.
Stout stems are light green to reddish purple and covered with stiff hairs. Branching occurs on the upper half of stems. The root system is fibrous and has short rhizomes.
Wildlife Value:
Host plant for 112 species of Lepidoptera, including silvery checkerspot and pearl crescent moth. Asters provide nectar and pollen to honey bees and specialized native bees, including masons, bumbles, and leaf cutters. Skippers, monarchs, and clouded sulphurs also visit for nectar. In fall and winter, the seedheads attract goldfinches, chickadees, nuthatches, towhees, and wild turkeys. Deer browsing helps to promote a bushy, sturdy growth habit.
Asters are an extremely important source of late-season pollen and nectar for honeybees and native bees stocking up on food for the winter. Monarchs also rely heavily on asters (and goldenrods) to prepare for migration. Additional visitors include dozens of moth species, flower flies, bee flies, and leaf beetles.
Medicinal, Edible, and Other Uses:
Native Americans used parts of aster plants to treat headaches and venereal diseases. Iroquois combined it with bloodroot and other plants to make a laxative. The root has been used for centuries in Chinese medicine to treat coughing and other lung conditions.
The flowers and leaves can be eaten fresh or dried, and Native Americans added aster to tea blends and salads. The flowers are gorgeous when used as a garnish, and leaves and flowers can be added to soups or salads. The leaves can also be cooked lightly and served like spinach.
Author Frances Denmore observed that Ojibwa gathered tendrils of the root and smoked them with tobacco to create a "charm" to attract wild game.
Caution: Parts of the plant may cause skin irritation in some people.