Sullivantia sullivantii (Torr. & Gray) Britt.
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Basis for Listing
Sullivantia sullivantii is limited to calcareous or circumneutral sedimentary cliffs in the Paleozoic Plateau of southeastern Minnesota. Many populations occur on cliffs with cool water seeping from porous rock and the protection of an overhanging ledge. This type of specialized cliff habitat is of very limited extent in the state. When S. sullivantii was designated a state endangered species in 1984, only 3 locations were known in Minnesota. Furthermore, at that time it was considered a separate species, S. renifolia, which was believed to be restricted to the Paleozoic Plateau of Minnesota and Iowa, and to the Missouri Ozarks.
Sullivantia sullivantii is a small, delicate perennial whose flowers have 5 white, ovate petals; 5 stamens; and a 2-beaked, many-seeded capsule. The flower stalks and calyx are conspicuously glandular. The lower bracts of the branched inflorescence are mostly 3-cleft. The stems are slender, nearly leafless, and rise from a short underground stem. The long-stalked leaves are hairless, kidney-shaped, and divided into broad lobes with spreading, pointed teeth (Gleason and Cronquist 1991).
Records from the 18 known S. sullivantii sites in Minnesota indicate that this species is limited to north-facing cliffs of dolomite, sandstone, or limestone. Plants are associated with cool, shaded, moist sites, where cool water seeps from porous rock. Many of the cliffs are fairly small and support only a few plants. Sullivantia sullivantii is often found rooted in moss in cracks or crevices in the cliff face, and on shallow ledges. It may be situated anywhere from the base to the upper slopes of the rock formation. Plants also occur, though rarely, on mossy boulders below a cliff. Sullivantia sullivantii habitats are most often found in well-shaded conditions in maple-basswood forests. Common associates are Cystopteris bulbifera (bulblet fern), Dodecatheon radicatum (jeweled shooting star), Cryptogramma stelleri (slender cliff brake), and liverworts.
Biology / Life History
Little is known about the biology and life history of S. sullivantii. It is known to be a rhizomatous, perennial herb. Leaves emerge in early to mid-May. Flowers appear in early to mid-June and seeds mature by mid-July. Plants often grow in rather dense patches, limited in extent by the size of their ledge habitat or the amount of fracturing of the bedrock. Plants in abundantly moist settings are more robust than those in less moist settings. It appears that S. sullivantii occupies a narrow ecological niche, implying that it has a very limited ability to compete.
Conservation / Management
Because S. sullivantii favors relatively inaccessible cliffs, habitat loss for this species is uncommon. However, the rarity of this habitat type in Minnesota coupled with the intensity of recent surveys suggests that the majority of the locations of S. sullivantii in Minnesota have been discovered. Thus, while this species occurs in habitats that are not typically threatened by development, it is important that all occupied habitat be monitored carefully. Adverse impacts would most likely come from quarrying or road construction, or from land use changes that result in warming and drying of its cliff habitat. Extensive removal of the forest canopy surrounding cliffs occupied by S. sullivantii could increase exposure of the cliff, which may induce physiological stress to cliff-dwelling plants. Further research is needed on the habitat, life history, population trends, reproductive biology, ecology, and population demographics of this rare species, as are beneficial management practices that protect its sensitive habitat.
Conservation Efforts in Minnesota
Several locations of S. sullivantii are in State Parks or on State Forest lands. Where the potential exists for human disturbance on these lands, special protection should be afforded this species and its rare habitat. The continued observation, monitoring, and protection of these sites will be necessary for the survival of S. sullivantii populations.
Gleason, H. A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. Second Edition. New York Botanical Garden, Bronx, New York. 910 pp.