Agalinis gattingeri (Small) Small ex Britt.
Round-stemmed False Foxglove
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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.
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).
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).
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.