2001 THE MICHIGAN BOTANIST 73

MULBERRY WEED (FATOUA VILLOSA) SPREAD AS FAR NORTH AS MICHIGAN

A.A. Reznicek University of Michigan Herbarium 3600 Varsity Drive, Suite 112 Ann Arbor, Michigan 48108-2287 [email protected]

Mulberry weed, Fatoua villosa (Thunb.) Nakai, also known as hairy crab- weed, is a warm temperate annual widespread in Asia and introduced and rapidly spreading in North America. It first appeared in North America in Louisiana, where Thieret (1964) noted “Dr. Joseph Ewan of Tulane University informs me that the plant has been found as a weed in New Orleans for at least 15 years.” This implies that it entered North America at least as early as the late 1940s. Thieret comments that “seedlings were frequent on the campus [of the University of Southwestern Louisiana] this past spring, even following the se- vere winter of 1962–63, when the temperature in LaFayette dropped to 15 de- grees F.” This suggested, somewhat ominously, that the plant could become weedy over a much larger area than the extreme south. Indeed, it was reported from Florida in 1974 (DuQuesnay 1974) and, by 1975, it had been also found in Alabama, Georgia, Mississippi, and North Carolina (Massey 1975). In 1977, per- haps belatedly, it was listed as an economically important foreign weed that po- tentially could be a problem in the United States (Reed 1977). The distribution of Fatoua as mapped and reported in Flora North America now encompasses all of the southeast, including Texas, and north to Oklahoma, Arkansas, Indiana, Kentucky, Maryland, and West Virginia (Wunderlin 1997). It has also been re- ported from California (Sanders 1996), Washington (Washington State Noxious Weed Control Board 2001), and is now known from southern Missouri (Yatskievych & Raveill 2001). Fatoua has recently also been reported from even closer to Michigan, as Vincent (1993) noted its occurrence in south central Ohio. Still, it was a surprise to see Fatoua in southern Michigan. Stopping at a rest area along I-94 west of Jackson (Jackson County), I noticed Fatoua locally abundant in some ornamental plantings surrounding the buildings. In some small areas, the plants were so dense as to be a solid ground cover, and hundreds of plants were present. Fatoua is becoming a problem weed in containerized nursery stock (Neal, 1998), and it likely is spread widely and rapidly by planting of containerized stock. The Michigan station was not likely a new introduction that year, as it was most frequent in an area of perennial ground cover that had obviously been planted at least several years before and the plant presumably had been building up its population for several years at least to reach such numbers. Morphologically, Fatuoa villosa somewhat resembles a seedling white mul- berry (Morus alba L). The alternate leaves are roughly similar in arrangement 74 THE MICHIGAN BOTANIST Vol. 40 and overall appearance. They are however, finely hispid, and the general aspect of the plant also strikes one as nettle–like. The axillary flowers are arrayed in greenish to purple-tinged, loose, hemispherical heads, giving an unusual appear- ance to the plant. Illustrations are found in Wunderlin (1997) and photos on the internet at www.ces.ncsu.edu/depts/hort/weeds/mweed1.html.

Specimen Citation:

MICHIGAN. Jackson Co.: Rest area on S side of I-94 ca. 0.8 mi W of Business 94 exit on 1 west side of Jackson, SE ⁄4 sect. 25, T2S R2W, North Lat. 42° 16′ 15″ West Long. 84° 25′ 40″ (from map). Weed in perennial ground cover planting (low junipers) in beds around rest area building, Sept. 25, 2001, A.A. Reznicek et. al. 11300 (MICH, MSC, MU, and numerous du- plicates to be distributed).

LITERATURE CITED DuQuesnay, D. 1974. Fatoua villosa (Moraceae) in Florida. Sida 5: 286. Massey, J.R. 1975. Fatoua villosa (Moraceae), Additional notes on distribution in the southeastern United States. Sida 6:116. Neal, J.C. 1998. Mulberry Weed or Hairy Crabweed (Fatoua villosa). Horticulture Information Leaflet #903. North Carolina Cooperative Extension Service. Reed, C.F. 1977. Economically Important Foreign Weeds—Potential Problems in the United States. USDA Agriculture Handbook 498. Sanders, A.C. 1996. Noteworthy collections-California. Madroño 43: 524–532. Thieret, J.W. 1964. Fatoua villosa (Moraceae) in Louisiana: New to North America. Sida 1: 248. Vincent, M.A. 1993. Fatoua villosa (Moraceae), Mulberry Weed, in Ohio. Ohio Journal of Science 93: 147–149. Wunderlin, R.P. 1997. Moraceae. In: Flora of North America Editorial Committee, eds, Fl. North Amer. 3:388–399 Oxford University Press, New York and Oxford. Yatskievych, G., & J.A. Raveill. 2001. Notes on the increasing proportion of non-native angiosperms in the Missouri flora, with reports of three new genera for the state. Sida 19: 701–709. Washington State Noxious Weed Control Board. 2001. http://www.wa.gov/agr/weedboard/ index.html

REVIEWS

DISTRIBUTION AND HABITAT DESCRIPTIONS OF WISCONSIN LAKE PLANTS. Stanley A. Nichols. 1999. Wisconsin Geological and Natural History Survey, Bulletin 96. xi + 266 pages + two unnumbered pages at the back; metal- ring binding with a sturdy plastic cover. $15 + $3.25 postage and handling, avail- able from Wisconsin Geological and Natural History Survey, 3817 Mineral Point Road, Madison, WI 53705. Telephone orders at 608. 262. 1705, with V or MC only. www.uwex.edu/wgnhs/, but no sales via that site.

This is not a taxonomic monograph. The names are simply taken from Glea- son & Cronquist, ed. 2, 1991. There are no keys. There are no descriptions. There are 107 species treated, by my rough count, in alphabetical order by Latin name, and nearly all are accompanied by a faithful and well-reproduced draw-