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NOTEWORTHY COLLECTION

THE DISCOVERY OF RHEXIA MARIANA L. VAR. MARIANA (MELASTOMATACEAE) IN NORTHWEST INDIANA

Scott A. Namestnik Orbis Environmental Consulting P.O. Box 10235 South Bend, Indiana 46680 snamestnik@orbisec.com

Significance of the Report. Prior to this collection, Rhexia mariana var. mariana had not been documented in northern Indiana or in the 22-county Chicago region, as defined in Swink and Wilhelm (1994) and Wilhelm and Rericha (2017).

Previous Knowledge. Rhexia mariana L. var. mariana (Melastomataceae), the Maryland meadow beauty (Figure 1), is a perennial herb of dry to moist sandy soil and full to partial sun conditions, occurring primarily in sandhills, sa- vannas, flatwoods, meadows, marshes, ditches, bogs, edge of thickets, and upper shores of ponds and swales (Correll and Johnston 1979; Radford et al. 1968; Voss and Reznicek 2012; Wunderlin and Hansen 2003). It is one of several species with a core geographical distribution along the Gulf of Mexico and At- lantic Ocean coastal plains (in this case reaching from Texas to Massachusetts) and with disjunct populations around the Great Lakes (in this case in southwest Michigan prior to the recent collection) (Reznicek 1994); the core of the range of R. mariana var. mariana stretches inland to southeastern Missouri, southern Illinois, and southern Indiana (Kartesz 2015; USDA, NRCS 2018). Although it had not been documented from the 22-county Chicago region prior to this col- lection (Kartesz 2015; Swink and Wilhelm 1994), R. mariana var. mariana is ex- tant in Allegan and Ottawa counties in Michigan, just north of the easternmost extent of the Chicago region (Voss and Reznicek 2012). In Indiana, R. mariana var. mariana was known from the southern third of the state, where it formed the boundary of the known core of its coastal plain distribution (Deam 1940; Kartesz 2015). Across its range, R. mariana var. mariana is globally secure (G5T5), but at the edge of its range in Indiana, it is critically imperiled (S1) and state threat- ened, and in the disjunct portion of its range in Michigan it is critically imperiled to imperiled (S1S2) and state threatened (IDNR-DNP 2016; Michigan Natural Features Inventory 2007; NatureServe 2017).

Discussion. A large, dense population of Rhexia mariana var. mariana esti- mated to include over 10,000 stems was discovered along the Calumet Bike Trail in a remnant mesic sand prairie within an overhead powerline right-of-way (Fig- ure 2) in Porter County, Indiana in 2014. A brief search of the right-of-way and of the savanna and woodland in the immediate vicinity following the discovery did not result in the observation of any additional colonies of R. mariana var. mariana. This population is approximately 200 miles from the nearest Indiana

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FIGURE 1. Rhexia mariana L. var. mariana along the Calumet Trail, Porter County, Indiana. Photo by Scott A. Namestnik.

populations at the edge of the core of the range of the species and is approxi- mately 80 miles from the nearest southwest Michigan populations; as a result it helps to fill the gaps in the known disjunct range of R. mariana var. mariana around Lake Michigan. After becoming aware of this population, on October 6, 2018 Doug Botka located another population of approximately 90 individuals of Rhexia mariana var. mariana in adjacent LaPorte County, Indiana at 41°42¢49.67¢¢, –86°49¢42.57¢¢, growing around the edge of an excavated pond with Acer rubrum L., Coleataenia rigidula (Bosc ex Nees) LeBlond, Dichanthe- lium ssp. (Hitchc. & Chase) Gould, Euthamia gymnospermoides Greene, Fran- gula alnus Mill., Nyssa sylvatica Marshall, Osmundastrum cinnamomeum (L.)

C. Presl, Oxycoccus macrocarpus (Aiton) Pursh, Pinus sylvestris L., Rhyn- chospora capitellata (Michx.) Vahl, Rubus sp. L., Schizachyrium scoparium (Michx.) Nash, Solidago rugosa Mill., Spiraea tomentosa L., Spiranthes incurva (Jenn.) M.C. Pace, Symphyotrichum praealtum (Poir.) G.L. Nesom, Toxicoden- dron vernix (L.) Kuntze, Vaccinium corymbosum L., and Vernonia sp. Schreb. (D. Botka, personal communication, October 7, 2018 and November 7, 2018). These discoveries should encourage field botanists to conduct additional tar- geted surveys for R. mariana var. mariana in appropriate habitat in proximity to Lake Michigan. Field botanists in this region should also be on the lookout for species with similar ranges as documented by Reznicek (1994) that have not yet Page  165 2018 THE GREAT LAKES BOTANIST 165

FIGURE 2. Habitat of Rhexia mariana L. var. mariana along the Calumet Trail, Porter County, Indi- ana. Photo by Scott A. Namestnik.

been documented in northwest Indiana (such as Bartonia paniculata (Michx.) Muhl.).

Diagnostic characters. Rhexia mariana var. mariana is one of 14 taxa (not including hybrids) in the genus, which is nearly endemic to the eastern United States (R. virginica L. reaches into Canada, and R. cubensis Griseb. reaches into the West Indies) (Kral and Bostick 1969; Nesom 2012). The following charac- teristics (from Kral and Bostick 1969 and Nesom 2012) can be used to distin- guish R. mariana var. mariana from the other taxa in the genus: the four petals are lavender-pink to white (not yellow as in R. lutea Walter); the anthers are 5– 11 mm long and curved (not ca. 2 mm long and nearly straight as in R. lutea, R. nuttallii C. W. James, and R. petiolata Walter); the stems and leaves are pubes- cent (not glabrous as in R. alifanus Walter); the bracts are narrower than the hy- panthia (not foliaceous and as wide as the hypanthia as in R. parviflora Chapm.); the hypanthia are up to 1 cm long (not over 1 cm long as in R. cubensis and R. nashii Small); and the stem faces are unequal, with two broader, darker green and convex, and the other two narrower, pale and concave (not equal and flat as in R. aristosa Britton, R. interior Pennell, R. salicifolia Kral & Bostick, R. ven- tricosa Fernald & Griscom, R. virginica, and sometimes in R. parviflora). The species to which R. mariana var. mariana is most similar are R. interior, R. ven- tricosa and R. virginica. Several characteristics can be used to distinguish R.

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FIGURE 3. Stem and leaves of Rhexia mariana L. var. mariana along the Calumet Trail, Porter County, Indiana. Photo by Scott A. Namestnik.

mariana var. mariana (Figure 3) from R. virginica, including leaves (linear to lanceolate, to 11 mm wide, and short petioled in R. mariana var. mariana versus ovate, over 11 mm wide, and sessile in R. virginica), stems (blunt angled in R. mariana var. mariana versus strongly wing-angled in R. virginica), and flower color (white to pale pink in R. mariana var. mariana versus pink-purple in R. vir- ginica) (Kral and Bostick 1969; Wilhelm and Rericha 2017); in addition, R. mar- iana var. mariana tends to grow in slightly dryer conditions and tends to flower slightly later than R. virginica (Voss and Reznicek 2012). The stems can be used to distinguish R. mariana var. mariana from R. interior and R. ventricosa (as noted above) (Kral and Bostick 1969; Nesom 2012). A variety of R. mariana with white petals and linear leaves, R. mariana L. var. exalbida Michx., is said to be distinct in portions of the range of the species, such as in North Carolina (Weakley 2015), but intergrades with R. mariana var. mariana are common, es- pecially in regions between the extremes of the varieties (Nesom 2012).

Specimen citations. INDIANA. PORTER CO.: Calumet Trail. 41°40¢4.7¢¢, –86°59¢53.5¢¢. Rather dense population in mesic sand prairie located within NIP- SCO right-of-way, just east of 5-mile marker on south side of Calumet Trail. More abundant in areas lacking Solidago rugosa and at slightly lower elevation than in immediately adjacent areas. Plants with buds, flowers, and fruit. Petals light pink (dried deeper pink). Associated species: Achillea millefolium, Agrostis gigantea, Dichanthelium clandestinum, Eragrostis spectabilis, Euphorbia corol-

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lata, Euthamia nuttallii, Galium pilosum, Hieracium kalmii, Juncus dudleyi, Juncus greenei, Lactuca canadensis, Liatris aspera, Linaria vulgaris, Lonicera sp., Melilotus albus, Panicum virgatum, Polygala polygama, Polytrichum sp., Po- tentilla simplex, Prunus serotina, Quercus palustris, Rubus baileyanus, Salix eri- ocephala, Schizachyrium scoparium, Solidago decemflora, Solidago juncea, Sol- idago rugosa, Spiraea tomentosa, Spiranthes cernua, Symphyotrichum oolentangiensis, Symphyotrichum praealtum, Viola sagittata. September 13, 2014, Namestnik 2242 (BUT, MOR).

LITERATURE CITED

Correll, D. S., and M. C. Johnston. (1979). Manual of the vascular plants of Texas. Second printing. The University of Texas at Dallas. Deam, C. C. (1940). Flora of Indiana. Department of Conservation, Division of Forestry, Indianapo- lis.

IDNR-DNP. (2016). Indiana Department of Natural Resources—Division of Nature Preserves. En- dangered, threatened, rare, and extirpated plants of Indiana. Available at https://www.in.gov/dnr/naturepreserve/files/np-etrplants.pdf (Accessed April 24, 2018).

Kartesz, J. T. (2015). The Biota of North America Program (BONAP). North American plant atlas. Chapel Hill, North Carolina [maps generated from Kartesz, J. T. 2015. Floristic synthesis of North America, version 1.0. Biota of North America Program (BONAP). (in press)]. Available at http://bonap.net/napa (Accessed April 24, 2018).

Kral, R., and P. E. Bostick. (1969). The genus Rhexia (Melastomataceae). Sida 3: 387–440. Michigan Natural Features Inventory. (2007). Rare species explorer (web application). Available on- line at http://mnfi.anr.msu.edu/explorer [Accessed April 24, 2018].

NatureServe. (2017). NatureServe Explorer: An online encyclopedia of life [web application]. Ver- sion 7.1. NatureServe, Arlington, Virginia. Available at http://explorer.natureserve.org. (Ac- cessed: April 24, 2018).

Nesom, G. L. (2012). Infrageneric classification of Rhexia (Melastomataceae). Phytoneuron 2012–

15: 1–9. Radford, A. E., H. E. Ahles, and C. R. Bell. (1968). Manual of the vascular flora of the Carolinas. The University of North Carolina Press, Chapel Hill. Reznicek, A. A. (1994). The disjunct coastal plain flora in the Great Lakes Region. Biological Con- servation 68: 203–215. Swink, F., and G. Wilhelm. (1994). Plants of the Chicago region. Fourth edition. Indiana Academy of Science, Indianapolis. USDA, NRCS. (2018). The PLANTS Database. National Plant Data Team, Greensboro, North Car- olina. Available at http://plants.usda.gov (Accessed April 24, 2018). Weakley, A. S. (2015). Flora of the southern and mid-Atlantic states. Working draft of 21 May 2015. Available at www.herbarium.unc.edu/flora.htm (Accessed November 6, 2018). Voss, E. G., and A. A. Reznicek. (2012). Field manual of Michigan flora. The University of Michi- gan Press, Ann Arbor. Wilhelm, G., and L. Rericha. (2017). Flora of the Chicago region: A floristic and ecological synthe- sis. Indiana Academy of Science, Indianapolis. Wunderlin, R. P., and B. F. Hansen. (2003). Guide to the vascular plants of Florida. Second edition. University Press of Florida, Gainesville.