Sullivantia sullivantii (Torr. & Gray) Britt.
Basis for Listing
In Minnesota, Sullivantia sullivantii (reniform sullivantia) 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 four 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 (Rosendahl 1927).
Since that time, S. renifolia has been redefined as a member of the more widespread, but still rare, S. sullivantii (Soltis 1991). Also since that time, intensive botanical surveys have been conducted in Minnesota, increasing the number of known locations to nearly 20, which likely represent five or six metapopulations. In light of these recent developments, S. sullivantii was reclassified as a state threatened species in 1996.
Sullivantia sullivantii is a small delicate perennial usually 10-20 cm (4-8 in.) tall. The flowers are very small, in the range of 2-3 mm (0.08-0.11 in.) and are borne in an open terminal panicle. Each has 5 ovate white 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 1-12 cm (0.4-4.7 in.) across, hairless, kidney-shaped, and divided into broad lobes with spreading, pointed teeth (Soltis 1991).
Habitats of the known S. sullivantii sites in Minnesota are from north-facing cliffs of dolomite, sandstone, or limestone within heavily forested regions of the Paleozoic Plateau. Plants are usually localized in cool, moist microhabitats where water seeps from porous rock. Plants are usually rooted in mossy cracks or crevices in the cliff face, and on shallow ledges. They 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. Most of the cliff habitats are well-shaded by the north-facing aspect and overhanging trees. Many of the habitats are fairly small and support only a few plants. Common associates are Cystopteris bulbifera (bulblet fern), Dodecatheon amethystinum (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. The flowers are apparently insect-pollinated (indicated by their morphology), but specific pollinators have not been identified. There is some indication that flowers may practice self-pollination (Soltis 1991). New plants are established only by seeds, which are small (in the 1 mm [0.04 in.] range).
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 the 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.
Best Time to Search
The best time to search for Sullivantia sullivantii is when in flower or fruit, from early June to mid-July. Leaves, flowering and/or fruiting stalks remain visible into mid-September.
Conservation Efforts in Minnesota
Several locations of S. sullivantii are on State Park or State Forest land. 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.
Welby R. Smith (MNDNR), 2023
(Note: all content ©MNDNR)
References and Additional Information
Rosendahl, C. O. 1927. A revision of the genus Sullivantia. Minnesota Studies in Plant Science 1(6): 401-427.
Solltis, D. E. 1991. A revision of Sullivantia (Saxifragaceae). Brittonia 43(1):27-53.