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Mikania scandens (L.) Willd. Asteraceae Climbing Hempweed

Previous knowledge. Mikania scandens is a vine found in wetlands of the eastern United States (USDA). It ranges from Florida to Maine and west to Texas and is considered a noxious weed in Hawaii. It was first reported from Michigan by C.D. McLouth (1896). The plant was brought to McLouth’s atten- tion in 1894, and that September, he observed it growing in the wetlands near the mouth of the Muskegon River in what is now Muskegon State Game Area (MSGA), Muskegon County. Inquiries to locals in the area allowed McLouth to conclude that M. scandens had been present since at least the mid-nineteenth century. This has remained the only report of M. scandens in Michigan up to the present (Reznicek et al. 2011). The nearest known populations are about 200 kilometers to the south in northern Indiana (Swink & Wilhelm 1994). Attempts to relocate this species in the areas described by McLouth have been unsuccess- ful, leading to this species being designated as extirpated from Michigan (Reznicek et al. 2011).

Significance of the Report. This is a significant find as this is the first report of this species in Michigan since it was originally reported by McLouth in 1896. I observed three populations, all roughly within 2 kilometers of each other. Only one of the populations was surveyed and there appeared to be about 50 healthy individuals setting seed at the coordinates provided on the collection label. The other populations were in remote areas and occurred in dense Cephalanthus oc- cidentalis thickets and only a few individuals were observed at each location. More thorough surveys are needed in the areas between Cedar Creek and the Muskegon River to accurately describe the condition of the metapopulation.

Diagnostic characters. Mikania scandens is a climbing herb of floodplains (Fig. 1), often twining up Cephalanthus occidentalis to heights of 3.0 m and oc- casionally forming mats over Phalaris arundinacea and Leersia oryzoides. The leaves are oppositely arranged at swollen nodes, deeply cordate, palmatly veined, and toothed. The flowers are small, pale-purple to white, and form loose corymbs born on axillary peduncles (MNFI 2007). Collected specimens were observed to be blooming throughout September. M. scandens may be mistaken for Ageratina altissima as the flowers are somewhat similar. However, M. scan- dens is a vine whereas A. altissima is a stout upright herb.

Specimen Citation. Mikania scandens (L.) Willd. Muskegon Co., Michigan: Muskegon State Game Area. 5 Miles SSW of Twin Lake. Lat. & Long.: 43° 17.

34.2 N, 86° 07. 41.1..W. Between Cedar Creek and the Muskegon River along the margins of openings in the Acer saccharinum dominated floodplain forest. Page  150 150 THE MICHIGAN BOTANIST Vol. 51

FIGURE 1. Mikania scandens in Muskegon State Game Area, MI. Photo taken by Jesse Lincoln on Oct 2, 2012.

Primarily climbing on Cephalanthus occidentalis and Fraxinus pennsylvanica. There seems to be a strong association of M. scandens and C. occidentalis. Also found occasionally forming mats atop Phalaris arundinacea. Highly localized but somewhat abundant. The majority of individuals observed were fruiting and scenesent at the time of collection, 3 October 2012. Jesse M. Lincoln; (MICH).


I would like to thank Dr. Tony Reznicek for his assistance editing this paper and for confirming the identity of Mikania scandens in the field. Todd Barkman also reviewed the article and provided helpful comments for improvements. Valerie Campbell assisted in the collection of samples and her efforts were appreciated.


McClouth, C.D. (1896). Mikania scandens Willd. Asa Gray Bulletin 4: 68 Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available on- line at [Accessed Nov 2, 2012] Reznicek, A.A., E.G. Voss, & B.S. Walters. (2011). University of Michigan. Web. Available at (Accessed 23 October 2012). Swink, F. & G. Wilhelm. 1994. Plants of the Chicago region, 4th ed. Indiana Academy of Science for Morton Arboretum, Indianapolis, Indiana. xiv + 921 pp. ——Jesse M. Lincoln 1510 Colorado SE, Grand Rapids, MI 49507