Plantago elongata Pursh
Basis for Listing
Plantago elongata (slender plantain) is an inconspicuous annual that reaches the extreme eastern limit of its range in southwestern Minnesota, where it is quite rare. It is more common farther west, though it appears to be local or infrequent in many parts of its range. Although P. elongata is native to Minnesota and is believed to have been present on the pre-European settlement landscape, there are no recorded occurrences prior to 1931 (Tryon and Moore 1946). The lack of early records presumably indicated that it was rare even at the time of settlement. When P. elongata was listed as threatened in 1984, there were only three recorded instances of the species in Minnesota and only one was known to survive. In addition, that one population was thought to consist of only about a dozen plants (Coffin and Pfannmuller 1988).
Since 1984, both of the historical records have been relocated, and an additional seven populations have been discovered. All of the populations are quite large, numbering in the hundreds or thousands of plants. Furthermore, the species appears to be tolerant of livestock grazing, as evidenced by its presence in several heavily grazed prairies. Plantago elongata is very small, and it is visible for only a short period of time before it disappears. This likely explains why it was overlooked in past surveys. This new information indicates this species is not as rare as previously thought, and threatened status is no longer necessary. For these reasons, its status was changed to special concern in 2013.
Plantago elongata is quite distinct from the other members of this genus that occur in Minnesota and can be easily identified, if not easily found. It is a dwarf, about 10 cm (4 in.) tall, with narrowly linear hairless leaves that are rarely more than 2 mm (0.08 in.) wide. Flowering spikes are also slender and usually overtop the leaves. Bracts are about as long as the sepals, somewhat ovate, and have a keel like that on a boat. Sepals have papery margins. There are 4 petals that are closed tightly over the fruit. There are 6-14 symmetrical oblong dark-brown seeds, with numerous tiny pockmarks (Bassett 1966).
All the records of P. elongata are from the Prairie Coteau region in southwestern Minnesota, specifically where Sioux Quartzite bedrock is exposed at the surface. Where these rock outcrops are exposed as flat terraces on gentle slopes, shallow pools may form between the outcrops or in depressions in the rock itself. These pools are sustained by seepage from between the strata or directly from precipitation. Seepage pools generally retain water longer than rain pools and may be wet through the warm months of the summer. Plantago elongata occurs in moist soil, at the edge of these pools.
Biology / Life History
Plantago elongata is an annual species, dependent upon adequate seed production and seed bank reserves for continued presence on a landscape. The reduced flowers of P. elongata are adapted for wind pollination (Primack 1978). Seed dispersal is likely accomplished by grazing or seed foraging animals, though no specifics are known. Evidence from research, conducted in the western part of the country, indicates P. elongata is adapted to survive in buffalo wallows (Polley and Wallace 1986). This might explain observations of P. elongata surviving in heavily grazed cow pastures in Minnesota. Not only can it grow in compacted soil, it is reported to be salt tolerant (Weber and Hanks 2006).
Conservation / Management
Habitat loss may be the greatest threat to P. elongata in Minnesota, though the habitats it occupies are not prime targets for agriculture. While much of this habitat has escaped farming and development, broadleaf herbicide application for weed control in pastures is a concern. Cattle can trample the delicate vegetation and provide opportunities for aggressive non-native species to invade. Mining of outcrops is also a major threat. Continued efforts at acquisition and protection of prairie remnants are essential. Additional surveys on suitable rock outcrops in southwestern Minnesota are also needed.
Best Time to Search
The best time to search for P. elongata is when flowering or fruiting, from late April through June. The plants disappear when outcrops become desiccated, by early July in most years.
Conservation Efforts in Minnesota
Plantago elongata is known from a State Park, a Wildlife Management Area, and a National Monument, but most known populations in the state are in intensely grazed pastures (where they may be threatened by herbicide applications for thistle control) and potential mining operations.
Welby Smith (MNDNR), 2008 and 2018
(Note: all content ©MNDNR)
References and Additional Information
Bassett, I. J. 1966. Taxonomy of North American Plantago L., Section Micropsyllium Decne. Canadian Journal of Botany 44(4):467-479.
Coffin, B., and L. Pfannmuller, editors. 1988. Minnesota's endangered flora and fauna. University of Minnesota Press, Minneapolis. 473 pp.
Harris, F. 2009. Rock pools on the prairie: ephemeral pools on the prairie form amazing mini-ecosystems. Minnesota Conservation Volunteer 72(423):30-39.
Hitchcock, C. L., and A. Cronquist. 1973. Flora of the Pacific Northwest: an illustrated manual. University of Washington Press, Seattle, Washington. 730 pp.
Johnson, J. R., and G. E. Larson. 1999. Grassland Plants of South Dakota and the northern Great Plains. South Dakota State University, Brookings, South Dakota. 288 pp.
Minnesota Department of Natural Resources. 2005. Field guide to the native plant communities of Minnesota: the prairie parkland and tallgrass aspen parklands provinces. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 362 pp.
Minnesota Department of Natural Resources, Division of Ecological Resources. 2008. Rare species guide: an online encyclopedia of Minnesota's rare native plants and animals [Web Application]. Minnesota Department of Natural Resources, St. Paul, Minnesota. Accessed 1 July 2009.
Polley, H. W., and L. L. Wallace. 1986. The relationship of plant species heterogeneity to soil variation in buffalo wallows. The Southwestern Naturalist 31(4)493-501.
Primack, R. B. 1978. Evolutionary aspects of wind pollination in the genus Plantago (Plantaginaceae). New Phytologist 81(2):449-458.
The Great Plains Flora Association. 1986. Flora of the Great Plains. University Press of Kansas, Lawrence. 1,402 pp.
Tryon, R. M. Jr., and J. W. Moore. 1946. Notes on aquatic and prairie vegetation in southwestern Minnesota. Rhodora 48(570):113-116.
Voss, E. G. 1996. Michigan Flora. Part III: Dicots (Pyrolaceae-Compositae). Cranbrook Institute of Science Bulletin 61 and University of Michigan Herbarium, Ann Arbor, Michigan. 622 pp.
Weber, D. J., and J. Hanks. 2006. Salt tolerant plants from the Great Basin region of the United States. Pages 69-106 in Ecophysiology of High Salinity Tolerant Plants. Springer Science & Business Media, Berlin, Germany.