Rare Species Guide

  Synonyms

Gerardia gattingeri

  Basis for Listing

This unusual plant follows a familiar pattern of occurrence that is typical of many rare species with wide distribution. Agalinis gattingeri is declining across much of its range, especially in the northern portion, but it appears to be secure in a smaller region at the center of its range. In this case, the decline of the peripheral populations could cause a significant loss of genetic diversity long before the species as a whole becomes threatened. Such a decline may now be taking place in Minnesota, but the lack of documentation makes it difficult to determine.

There are only 5 documented occurrences of A. gattingeri in Minnesota, and 3 date from the 19th century. This collection history seems to describe a very rare species that suffered a decline beginning late in the 19th century. Such a decline cannot be solely explained by habitat loss because the sandy and rocky prairies preferred by this species are not intensively exploited, and the original extent of this habitat type has probably not been significantly reduced. Agalinis gattingeri was listed as a threatened species in Minnesota in 1984, but given its extreme rarity, it was reclassified as endangered in 1996.

  Description

Agalinis gattingeri is an upright herb with slender, ascending branches and linear leaves. Stems are somewhat round in cross section. Flowers appear in late summer and turn from pink to pinkish-purple upon drying. It has a 5-cleft flower with the upper 2 lobes smaller and more united than the lower 3 lobes. The lower lobes and throat have soft hairs, with 2 yellow lines and many purplish-red spots decorating the inside of the throat. Leaves are shorter than the flower stalk. Agalinis gattingeri plants remain more or less green upon drying. This species is similar to A. aspera (rough gerardia), which may occur in the same habitat, but has a stem that is rough to the touch (Canne-Hilliker 1987; Ostlie 1990; Voss 1996).

  Habitat

The population of A. gattingeri in Winona County occurs on a hillside prairie in sandy soil. The site has a dry, sunny, south-facing exposure and is typical of such habitats in that region. There is no habitat description for the 19th-century collections, but judging from their origins in the Mississippi and St. Croix river valleys, it is likely that they came from hill prairies as well.

  Biology / Life History

This plant is an annual hemiparasite. It is not certain which species serve as its host, but other species in the genus Agalinis form attachments to almost any neighboring root. Agalinis gattingeri is most abundant in association with taller, clump-forming grasses. The floral design is consistent with insect-pollinated flowers: yellow lines leading to purplish-red spots would seem to attract insect pollinators. Plants flower from August to mid-September and occasionally into early October. Each flower opens for a single day, the corolla falling from the plant in late afternoon. Seeds are produced mainly in September. Capsules contain numerous seeds that may be shaken by the wind, dispersing the seeds. An annual, this species is dependent upon previously produced seed for regeneration. As is typical in annuals, large annual fluctuations in abundance are noted in its populations. Seeds may remain dormant in the soil for years until favorable germination conditions occur. The length of seed viability in these seed banks is unknown (Canne-Hilliker 1987; Ostlie 1990).

The best time to search for A. gattingeri is during flowering, from mid-August to early October.

  Conservation / Management

Threats to A. gattingeri include human activities such as road construction, agriculture, housing development, and off-road vehicles. Fire suppression poses a threat as it allows succession from grassland to woodland. Some grasslands are endangered by Euphorbia virgata (leafy spurge) infestations and could pose a grave threat to A. gattingeri populations (Canne-Hilliker 1987; Ostlie 1990). It is recommended that lands harboring this species as well as adjacent buffer lands be protected. Buffer protection is important to restrict herbicide drift, to support pollinators, and to ease management with prescribed fire. A regimen of dormant season prescribed fire at intervals of 3-5 years should be considered on sites so as to maintain the open grasslands or savanna that it prefers. Leafy spurge infestations should be identified and destroyed immediately. It is advised that annual, late summer monitoring of populations be conducted. Such monitoring may include a population census, habitat changes and trends, status of non-native invasive species, and encroachment of human activities from adjacent lands. Surveys should be conducted on potential habitat because data on the current range of A. gattingeri is poorly known. Further study would be useful. More information is needed concerning host specificity, germination requirements, and pollination ecology (Canne-Hilliker 1987; Ostlie 1990).

  Conservation Efforts in Minnesota

The Minnesota DNR County Biological Survey has been completed in the likely range of this species in the state.

  References and Additional Information

Canne-Hilliker, J. M. 1987. Status report on Gattinger's Purple False Foxglove, Agalinis gattingeri (Small) Small, an endangered species in Canada. Report submitted to the Committee on the Status of Endangered Wildlife of Canada, Ottawa, Ontario, Canada. 19 pp.

Dieringer, G. 1999. Reproductive biology of Agalinis skinneriana (Scrophulariaceae), a threatened species. Journal of the Torrey Botanical Society 126(4):289-295.

NatureServe. 2006. NatureServe Explorer: An online encyclopedia of life [web application]. Version 5.0. NatureServe, Arlington, Virginia. . Accessed 19 July 2006.

Ostlie, W. 1990. Element stewardship abstract for Agalinis gattingeri - Gattinger's false foxglove, round stem foxglove. The Nature Conservancy, Minneapolis, Minnesota.

Salamun, P. J. 1951. Preliminary reports on the flora of Wisconsin. XXXVI. Scrophulariaceae. Pages 111-138 in A. J. Ihde, editor. Transactions of the Wisconsin Academy of Sciences, Arts, and Letters. Volume XL. Part 2. Wisconsin Academy of Sciences, Arts and Letters, Madison.