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Bradford S. Slaughter Orbis Environmental Consulting P.O. Box 10235 South Bend, IN 46680

Tim Walters Botanical and Wetland Consulting 30536 NE Coyote Drive Yacolt, WA 98675

Significance of the Report. The first reports of this species from the Great Lakes region, including Ohio and Michigan.

Previous knowledge. Juncus validus Coville (roundhead rush) is a perennial wetland generalist of the south-central and southeastern United States. Prior to 1900, the species was known from a relatively restricted area of Oklahoma, Texas, Arkansas, and Louisiana, with one outlying (and likely non-native) population in Mississippi. From this putative natural range, J. validus has since spread east and north across the southeastern United States to Maryland and Delaware (Knapp 2014). These eastern populations have been conflictingly interpreted as native and of conservation concern (Kentucky and North Carolina) or as non-native (Delaware, Maryland, and Virginia) (NatureServe 2017). Rangewide, J. validus is considered globally secure (G5) by NatureServe (2017).

Discussion. Two small patches of Juncus validus were documented in 2008 along a moist to dry sandy road created by off-road trucks in Lucas County, Ohio. The population persisted through 2009 and was not found in 2010. In 2011, a new population of 70 plants was found approximately 300 meters from this location in a palustrine sand plain wetland created in 2010. This population expanded to over 100 plants in 2015. The species has not reappeared in the original location, which has become much drier and is apparently no longer periodically saturated.

In 2015, a large population of Juncus validus was documented in a disturbed, wet railroad right-of-way in Berrien County, Michigan. This is approximately 241 km (150 mi) WNW of the Ohio populations and 600 km (370 mi) NE of the nearest previously documented population in Alexander Co., Illinois (R. Mohlenbrock 18991, MO).

The recent documentation of Juncus validus in Ohio and Michigan follows similar discoveries of this species over the past several decades at localities east


FIGURE 1. The inflorescence of Juncus validus showing the nearly spherical or spherical heads, which are similar to but larger than those of the rare native J. scirpoides. Photo by B.S. Slaughter.

and north of its apparent native range (Knapp 2014). However, the Ohio and Michigan populations are considerably disjunct, both from the putative native range and from each other, and suggest that the species may be present but overlooked elsewhere in the Upper Midwest.

Diagnostic Characters. Juncus validus is placed in Juncus sect. Ozophyllum (= subg. Septati), the largest section in the genus, which is characterized by perfectly septate leaves and by flowers that lack subtending bracteoles (Brooks and Clemants 2000; Knapp 2014). Juncus validus can be identified by its combination of rhizomatous stems; laterally compressed leaves; spheric or nearly spheric, many-flowered heads; flowers with three stamens and largest tepals 4– 5 mm long; capsules exserted or slightly included with valves separating at dehiscence into three distinct portions at the apex; and clear, untailed, yellow- brown seed bodies (Brooks and Clemants 2000; Knapp 2014). In the Great Lakes region, J. validus (Figure 1) is most likely to be confused with J. scirpoides Lam., from which it differs in its larger mature heads (12–15 mm vs. 7– 12 mm diameter), longer tepals (3.5–4.5 mm vs. 2–3 mm), longer capsules (4.5–

5.5 mm vs. 3–4 mm), and lack of tuberous rhizomes (MICHIGAN FLORA ONLINE 2011). Specimen Citations. Ohio. Lucas County: NE ¼ Sec 12, T07N R09E. Two small clumps each with ca. 20 plants. Edge of palustrine sandy depression, 70 percent vegetated. 0.45 miles north of Salisbury Road and 0.44 miles west of Crissey Road. 41.589258, –83.769717. Associates: Ludwigia palustris, Juncus


biflorus, Fimbristylis autumnalis, Panicum rigidulum, Populus deltoides seedlings, Eleocharis acicularis. September 2, 2008. Walters 14448 (MICH, CLM).

Michigan. Berrien County: NW¼ Sec. 20, T07S R20W. Scattered colonies on disturbed peaty sand and clay in right-of-way between railroad and Red Arrow Hwy just S of Barker Ln. 41.853517, -86.660564. Associates: Eleocharis elliptica, Gentianopsis crinita, Juncus tenuis, J. torreyi, Linum medium, Lythrum salicaria, Sorghastrum nutans, Thelypteris palustris. September 1, 2015. Slaughter 1521 (MICH). Det. A.A. Reznicek March 17, 2016.


Brooks, R. E., and S. E. Clemants. (2000). Juncus. Pp. 225–255 in Flora of North America, volume

22. Magnoliophyta: Alismatidae, Arecidae, Commelinidae (in part), and Zingiberidae. Flora of North America Editorial Committee, editors. Oxford University Press, New York. Knapp, W. M., R. F. C. Naczi, W. D. Longbottom, C. A. Davis, W. A. McAvoy, C. T. Frye, J. W. Harrison, and P. Stango III. (2011). Floristic discoveries in Delaware, Maryland, and Virginia. Phytoneuron 2011-64: 1–26.

Knapp, W. M. (2014). Juncus fascinatus (Juncaceae), a new combination in Juncus sect. Ozophyllum and notes on morphologically similar species. Phytotaxa 174: 243–260. MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, and B. S. Walters. (2011). University of Michigan. Available at (Accessed March 26, 2016).

NatureServe. (2017). NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available at (Accessed March 27, 2018).