Rare Species Guide

  Basis for Listing

Taenidia integerrima (yellow pimpernel) is an uncommon species of southeastern Minnesota. Its fate is closely linked to remnants of the original oak ecosystem, especially oak savannas and oak openings. Although these habitat types were common at the time of settlement, they have since become quite rare, which is a downward trend that continues today (Minnesota's Remaining Native Prairie, which includes oak openings). There have been approximately 40 records of this species in about a dozen counties in southeastern Minnesota (Eastern Broadleaf Forest Province). Several of these sites have been lost, and there is concern that the remaining sites may not harbor enough plants to be considered viable; hence, Taenidia integerrima was designated special concern in 2013.

  Description

Stems of T. integerrima are erect, smooth, and 40-80 cm (16-32 in.) tall. Immature or non-reproductive individuals lack a stem and consist of only a basal rosette of leaves. Leaves are compound, divided once, twice, or three times. The leaflets are unlobed, entire, and often have a mucronate tip. The inflorescence consists of one or a few umbels, with numerous small yellow flowers. The fruit is a dry 2-seeded structure, 4-5 mm (0.16-0.20 in.) long, and 3-4 mm (0.12-0.16 in.) wide. It is slightly compressed laterally and has low and distinct ribs. The roots are tuberous-thickened and mostly vertical.

Among similar-looking species that occur within the same family, such as Zizea aurea (golden alexanders) or Z. aptera (heart-leaved alexanders), T. integerrima is distinguished by umbels that are more open and leaflets that lack lobes or teeth.

  Habitat

In Minnesota, T. integerrima is associated with upland deciduous woods ranging from oak savannas and woodlands to drier hardwood forests and even the margins of dry cliffs. Soils are typically rather dry coarse textured sand or sandy loam. Soils in mesic hardwood forests are more likely to be clay loams. Full shade is tolerated, though not preferred. Direct or filtered sunlight for at least a portion of the day seems to be preferable.

  Biology / Life History

Taenidia integerrima is a long-lived perennial, and under ideal conditions all mature individuals will produce flowers and seeds each year. Pollination is accomplished by flies and solitary bees. The floral and inflorescence characters appear to be specialized to favor outcrossing, even though there is almost full self-compatibility (Lindsey and Bell 1985).

Seed dispersal appears to have no animal vector. The seeds apparently just fall to the ground and germinate wherever gravity takes them. One published report found an average of 77 seeds per umbel (Werier 2002), and each plant will produce one to a few umbels.

Taenidia integerrima does not produce adventive rhizomes or suckering roots. Occasionally a second crown will be produced, which will in turn produce a second stem, but these new crowns are very close to the original crowns and do not constitute “dispersal”, nor do they appreciably enlarge the size of the colony.

  Conservation / Management

Taenidia integerrima appears to do well as long as its habitat continues to support basic ecosystem functions. From the point of view of T. integerrima, these functions include an adequate diversity and abundance of pollinators, stable soil conditions, protection from invasive non-native species, and balanced dynamics between edge and interior environments. One concern is that many of the surviving habitats have been so fragmented and isolated that they may no longer perform these functions. If that is the case, then it may be necessary to simulate these functions through surrogate actions, such as cutting or pulling non-native species, prescribed burns, soil erosion barriers, and so forth.

  Best Time to Search

The presence of flowers and/or fruits will make searching for T. integerrima easier but are not essential for positive identification. The best time to search is during the months of June, July, and August.

  Authors/Revisions

Welby Smith (MNDNR), 2018

(Note: all content ©MNDNR)

  References and Additional Information

Lindsey, A. H., and C. R. Bell. 1985. Reproductive biology of Apiaceae II. Cryptic specialization and floral evolution in Thaspium and Zizia. American Journal of Botany 72(2):231-247.

Minnesota Department of Natural Resources. 2005. Field guide to the native plant communities of Minnesota: the eastern broadleaf forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 394 pp.

Minnesota Department of Natural Resources. 2006. Tomorrow's habitat for the wild and rare: An action plan for Minnesota wildlife, comprehensive wildlife conservation strategy. Division of Ecological Services, Minnesota Department of Natural Resources. 297 pp. + appendices.

Minnesota Department of Natural Resources. 2009. Map of Minnesota's remaining native prairie 100 years after the public land survey. . Accessed 19 June 2009

NatureServe. 2009. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia.

Robert W. Freckmann Herbarium. 2009. Flora of Wisconsin: Consortium of Wisconsin Herbaria [web application]. University of Wisconsin, Stevens Point. <http://wisflora.herbarium.wisc.edu/>. Accessed 8 July 2009.

Werier, D. 2002. Tainidia integerrima (L.) Drude (yellow pimpernel). New England Plant Conservation Program, Conservation and Research Plan for New England. New England Wild Flower Society, Framingham, Massachusetts.