Baptisia bracteata var. glabrescens (Larisey) Isley
Plains Wild Indigo
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Baptisia leucophaea, Baptisia leucophaea var. glabrescens
Basis for Listing
Baptisia bracteata var. glabrescens is a long lived, dry to dry-mesic prairie species that reaches the northwestern limit of its range in southeastern Minnesota. It was likely a common element of prairies in that region of the state prior to human settlement. However, since that time the species has declined mostly as a direct result of the large-scale conversion of the prairie and savanna landscape to row-crop agriculture. Bluff prairie and hill prairie populations (and other areas that haven't been converted to cropland) have declined due to livestock grazing and fire suppression, both of which have contributed to invasion of woody vegetation, especially Juniperus virginiana (eastern red cedar), and the elimination of prairie habitat.
Baptisia bracteata var. glabrescens is a sprawling, shrub-like, herbaceous perennial that reaches a height of 30-75 cm (11.8-29.5 in.). Plants are pubescent throughout. Leaves are palmately compound with 3 (occasionally 5) leaflets, and 2 leaflet-like stipules at the base. The inflorescence of B. bracteata var. glabrescens is a drooping raceme (an elongate flowering structure in which the first flowers to open are those at the bottom of the inflorescence) up to 20 cm (7.9 in.) long. Flowers have the typical appearance of legumes. They are white-pale cream to yellow in color. Each flower is 2-2.5 cm (0.75-0.98 in.) long. Once pollinated, fuzzy, elliptical pods develop with distinct, pointed beaks. When the plant dries, it turns black-gray, breaks easily, and has the appearance of a "tumbleweed".
Baptisia bracteata (the full species) has a wide range throughout the Midwest and the southeastern United states, but the variety that occurs in Minnesota is primarily restricted to the Midwest. It ranges from southeastern Minnesota, east to Michigan and Ohio, and south to Mississippi and Texas. In Minnesota, B. bracteata var. glabrescens is most often found in dry prairies, dry savannas, mesic prairies, and mesic savannas. Plants are also found in sandy soil as well as in the rocky bluff prairies of the Paleozoic Plateau (driftless area). Plants can be found persisting in prairie remnants along railroads, roads, and even occasionally in abandoned fields (Cochrane and Iltis 2000). Frequently associated plant species include: Andropogon gerardii (big bluestem), Bouteloua curtipendula var. curtipendula (side-oats grama grass), Schizachyrium scoparium var. scoparium (little bluestem), Sorghastrum nutans (Indian grass), Dalea purpurea var. purpurea (purple prairie clover), Brickellia eupatorioides var. corymbulosa (false boneset), Coreopsis palmata (bird's foot coreopsis), Solidago nemoralis (gray goldenrod), Juniperus virginiana var. virginiana (eastern red cedar), Amorpha canescens (leadplant), Eupatorium altissimum (tall boneset), Silphium laciniatum (compass plant), Eryngium yuccifolium (rattlesnake master), Calylophus serrulatus (toothed evening primrose), and Lespedeza capitata (round-headed bush clover).
Biology / Life History
Baptisia bracteata var. glabrescens is a perennial plant, and one of the earliest prairie plants to bloom each year. Flowers are pollinated by queens of Bombus bimaculatus and B. nevadiensis auricomis (bumble bees). The grubs of Apion rostrum (wild indigo weevil) can occasionally be found in the pods of B. bracteata var. glabrescens eating the seeds; adults feed on the leaves and flowers (Haddock and Chaplin 1982).
Conservation / Management
Baptisia bracteata var. glabrescens continues to be threatened by habitat loss. While the species is able to persist in roadsides and old fields long after its associates have been lost, changing land practices are now putting populations that have managed to survive at risk. For example, populations along roadsides and in rights-of-way are being impacted by increased uses of herbicides and excessive mowing. The spread of invasive species such as Euphorbia esula (leafy spurge) also poses a threat to the long-term survival of B. bracteata var. glabrescens. Burning is an important management tool that may be used to prevent woody species succession in prairie habitats, and in conjunction with limited, targeted herbicide application, it may be used to control leafy spurge.
Conservation Efforts in Minnesota
Several populations of B. bracteata var. glabrescens have been protected in Minnesota through land acquisitions by the Scientific and Natural Areas (SNA) program. Two of the most prominent SNAs include Wild Indigo Prairie SNA, a twelve mile long right-of-way abandoned by the Chicago-Milwaukee Railroad, and Kellogg-Weaver Dunes SNA. Additional populations of B. bracteata var. glabrescens are located in Wildlife Management Areas and city parks where they are safe from most land conversion activities, but likely not as protected from other forms of disturbance such as recreational activities and competing resource management objectives.
Cochrane, T. S., and H. H. Iltis. 2000. Atlas of the Wisconsin prairie and savanna flora. Wisconsin Department of Natural Resources and University of Wisconsin - Madison Herbarium Technical Bulletin No. 191, Madison, Wisconsin. 226 pp.
Haddock, R. C., and S. J. Chaplin. 1982. Pollination and seed production in two phenologically divergent prairie legumes (Baptisia leucophaea and B. leucantha). The American Midland Naturalist 108(1):175-186.
Hilty, J. 2009. Illinois Wildflowers.
Larisey, M. M. 1940. A monograph of the genus Baptisia. Annals of the Missouri Botanical Gardens 27(2):119-224.
Voss, E. G. 1985. Michigan Flora. Part II: Dicots (Saururaceae-Cornaceae). Cranbrook Institute of Science Bulletin 59 and the University of Michigan Herbarium. University of Michigan, Ann Arbor, Michigan. 727 pp.