Forked Aster (Aster furcatus)

In Wisconsin, native aster blossoms enliven roadsides, meadows and prairies in autumn. While many aster flowers are blue to purple many others, like the forked aster, are pure white. The flowers of all asters produce pollen and abundant nectar. This food is important to butterflies and to the survival of overwintering colonies of honeybees and other social insects. The seeds that follow the flowers become food for migrating and resident songbirds alike.

What does Forked Aster look like?

Forked asters are perennial herbs with creeping rhizomes below ground. These beautiful wildflowers typically reach heights of from one to three feet and are crowned with flat-topped or rounded clusters of snowy white flowers that bloom from August to October. With age, the flowers may take on lilac or rosy tones. Below the flowers lie a series of thick, jagged-edged leaves that are rough on top and finely bristled below. Upper leaves are oval while those toward the base of the plant are heart-shaped.

Where do forked asters grow in Wisconsin and in North America?

This rare species of aster is known only from six midwestern states: Arkansas, Indiana, Illinois, Iowa, Missouri, and Wisconsin. Within this range, the plants are very local in occurrence, with less than 50 known populations. Around a dozen of these populations are found in Wisconsin, where they are restricted to the southeastern portion of the state.

What conditions favor this aster?

Forked asters have been found growing in a wide variety of habitats: moist rocky ledges, stream floodplains, open oak woodlands, wooded ravines, railroad rights-of-way, and woodland edges. In order to become established, forked aster seedlings prefer open, alkaline soils, high light levels, and moderate moisture. Unfortunately, these conditions also favor the establishment of numerous other species which often quickly outgrow and exclude the slow growing forked aster seedlings. Consequently, forked asters are most likely to be found in areas where moderate levels of disturbance provide regular opportunities for seedling establishment. In Wisconsin, they are most commonly associated with wooded river and stream floodplain terraces.

How does the forked aster grow and reproduce?

Each spring, the perennial roots of the forked aster send up a new stem and a new complement of leaves. Throughout the growing season, the leaves capture energy from the sun and store it in a form that can be used by the plant. If enough energy has been stored, the plant produces flowers which start to bloom in August. Those flowers that are successfully pollinated will then produce seeds, a few of which may be fortunate enough to land on favorable sites, germinate and become established.

The forked aster is also capable of reproducing vegetatively. Late in the growing season, the plant sends out a shallow rhizome -- essentially an underground, horizontal stem. Roots are formed at the tip of the rhizome, and the following season a new shoot is sent up, resulting in a clone of the original plant. This is the more common form of reproduction in forked asters, and can often result in dense patches of genetically identical plants.

Why is the forked aster so rare?

The rarity of this species is probably due to a combination of poor seed reproduction and low levels of genetic diversity. In addition to this natural rarity, the forked aster is faced with a number of other threats. Principal among these is the loss of habitat through urbanization, especially in the rapidly growing Milwaukee-Waukesha region. Other significant threats include the absence of natural disturbance processes such as stream bank scouring, the unintentional trampling of river bank populations by recreational river users, and overshading by canopy closure. In urban areas where there is a high deer population, overbrowsing can be a problem. The forked aster has become sufficiently rare as to be listed as "Threatened" by the state of Wisconsin. The federal government has listed forked aster on its "candidate" list. These designations mean that this aster is very rare and requires protection to ensure its continued survival.

Why should we be concerned about the future of the forked aster?

The loss of the forked aster would mean the loss of a truly beautiful plant that has long played its role in the functioning of the healthy natural ecosystem. Lost too would be the potential of using the plant directly to benefit human beings. The Potawatomi Indians, for example, used the forked aster to cure severe headaches by steeping the leaves and then rubbing the solution into the scalp. What other potential uses might the plant hold?

What can I do to protect this valuable species?

The key to protecting this rare aster is to protect its habitat from destruction. Urbanization poses a significant threat to the few populations remaining in Wisconsin. It is also important to restrict the use of herbicides and insecticides near these plants. Herbicides may kill the plant outright, while insecticides may kill the insects that pollinate its flowers. Management tactics might include controlling vegetation such as non-native shrubs (e.g. European buckthorn and Tartarian honeysuckle) that overshades the aster. Another useful tactic would be actively decreasing urban deer herds. People interested in the protection of rare plants may support the efforts of public agencies such as the State of Wisconsin's Bureau of Endangered Resources, and those of private organizations such as The Nature Conservancy. Property owners on whose land the forked aster grows can help by keeping track of plant numbers and health, and then reporting this information to the Bureau of Endangered Resources.

To report forked aster sightings or to get more information, please contact:

Landowner Contact Specialist
Bureau of Endangered Resources
Department of Natural Resources
P.O. Box 7921
Madison, WI 53707
(608) 264-6039

Excerpt from The Endangered and Threatened Plants of Wisconsin

Synonym:

Status: threatened in Wisconsin

Habitat Description: oak woods and moist woods and edges, often near streams

Habitat Classification
WI NHI: Southern Mesic Forest, Southern Dry-Mesic Forest, Floodplain Forest
Curtis: Southern Mesic Forest, Southern Dry-Mesic Forest, Southern Wet-Mesic Forest
Kotar:
Forest Cover: Mixed Oak, Central Hardwood, Aspen possible

Range: Fond du Lac, Kewaunee, Milwaukee, Ozaukee, Racine, Rock, Sheboygan, Walworth, Washington, Waukesha, and Winnebago

Comments: associated with disturbance

Phenology: flowers from August through October

Field Guides:
Britton and Brown, p.3:444/p.3:445
Gleason 1963, p.723
Gleason 1991, p.587