CPC National Collection Plant Profile

Agalinis skinneriana

Thomas Antonio

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CPC National Collection Plant Profile

Agalinis skinneriana

Common Names: 
pale false foxglove, pale gerardia
(Wood) Britt.
Growth Habit: 
CPC Number: 


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Agalinis skinnerianaenlarge
Photographer: Thomas Antonio
Image Owner: Chicago Botanic Garden

Agalinis skinnerianaenlarge
Photographer: Thomas Antonio
Image Owner: Chicago Botanic Garden

Agalinis skinneriana is Fully Sponsored
Primary custodian for this plant in the CPC National Collection of Endangered Plants is: 
Andrea Tietmeyer contributed to this Plant Profile.

Agalinis skinneriana

This rare annual forb is a hemiparasite, meaning that it attains some of its nutrients by attaching its roots to those of other nearby species. Agalinis skinneriana generally occurs in small scattered populations throughout its range, which extends south from Ontario and Ohio to Missouri and Louisiana. It can be found in a number of different habitats, from sand to mesic prairies, and from rocky open glades to moist thickets. While it appears that this species has always been rare throughout its range, the number of populations appears to have declined since the 1800's (Kercher & Sytsma 2000). It is currently not federally protected, but is listed as threatened or endangered in 5 of the 12 states where it is currently found. A major threat to this species is loss of habitat, both from habitat destruction for development and from habitat degradation due to invasive species and fire suppression.

Research and Management Summary:
A number of studies have recently been performed on this species, as well as on other closely related species in the genus Agalinis. Management for this species, however, is lacking throughout most of its range.

Plant Description:
Agalinis skinneriana ranges in height from 10 to 65 cm (3.9 inches to 2.1 feet). On its slender, pale green stems are small, oppositely arranged leaves. Pale pink flowers form on a raceme with corollas that measure 1.0 - 1.5 cm in diameter. Flowering occurs at different times throughout this plant's range, but is generally from August to September.

Distribution & Occurrence

State Range
State Range of  Agalinis skinneriana
  In general, Agalinis skinneriana is described as a species found in the prairie. However, because it has a large geographical distribution, it can be found in a wide range of habitats, including but not limited to: dry to mesic prairies, open woods in shallow rocky soils, bluffs, barrens, pockets among dunes, sandy woods, and moist thickets. (Canne-Hilliker 1987, Trick 1995).

Plants that are often associated with this species include Agalinis purpurea, Aletris farinosa, Andropogon gerardii, Aster ptarmicoides, Calopogon tuberosus, Liatris spicata, Lobelia kalmii, Pycnanthemum virginianum, and Solidago ohioensis (Swink & Wilhelm 1994).

  Agalinis skinneriana has historically been reported from 16 states: Alabama, Arkansas, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Missouri, Nebraska, Ohio, Oklahoma, Tennessee, and Wisconsin, as well as southwestern Ontario, Canada. As of 1995, only 12 states were known to contain populations of Agalinis skinneriana, as it was considered extirpated in Alabama, Iowa, Nebraska, and Oklahoma (Trick 1995).

Number Left
  Currently, this species is found in:
7 Illinois counties (Robertson and Phillipe 1993)
26 Arkansas counties (Smith 1988)
7 sites in Indiana (Hedge et al. 1992)
3 sites in Kansas (Kansas Biological Survey 1994)
2-5 sites in Kentucky, 6 counties in Louisiana, & 1-2 sites in Tennessee (Ostlie 1990)
1 site in Maryland , 1-4 sites in Michigan, 24 locations in Missouri, & 5 sites in Wisconsin (Trick 1995)
3 populations in Ohio (Cusick 1993)
13 sites in southwestern Ontario (Canne-Hilliker 1987)

Trick (1995) reports that populations of Agalinis skinneriana are either in jeopardy, declining, or their status is unknown in every state where the plant is found except Arkansas, where the populations are apparently stable and not currently a concern.


Global Rank:  
Guide to Global Ranks
Federal Status:  
Guide to Federal Status
Recovery Plan:  

State/Area Protection
  State/Area Rank Status Date  
  Alabama SR 1/1/1994  
  Canada (Ontario) N2 E 11/1/2001  
  Illinois T 1/1/2002  
  Indiana S1 SE 4/10/1996  
  Iowa S1 E 8/1/2001  
  Kentucky S2 E 1/1/2000  
  Maryland S1 E 4/30/2001  
  Michigan S1 E 3/1/1999  
  Missouri S3 7/16/2001  
  Nebraska S1 3/7/1989  
  Ohio S1 E 1/1/2000  
  Oklahoma SR 1/1/1995  
  Ontario S2 5/23/1991  
  Wisconsin S1 E 1/12/2001  

Conservation, Ecology & Research

Ecological Relationships
  The flowers of Agalinis skinneriana are capable of pollinating themselves if they are not successfully pollinated by visiting insects during the short time (from 3-7 hours) that their pink corollas are open. (Dieringer 1999)
Visiting insects include bumblebees (Bombus pennsylvanicus, Bombus impatiens), solitary bees (Hymenoptera sp.) (Dieringer 1999), sulphur butterflies (Colias eurytheme) and honeybees (Apis sp.) (Trick 1995).
All species of Agalinis appear to be hemiparasites, meaning that their leaves perform photosynthesis while their roots form parasitic attachments to the roots of nearby species. Studies of Agalinis purpurea, a common associate and close relative of Agalinis skinneriana, have revealed no host specificity for these parasitic connections. (Trick 1995, Baird & Riopel 1984, Riopel & Musselman 1979).

  According to Trick (1995), threats include:
Encroachment of woody vegetation on prairie habitats due to fire suppression
Habitat conversion for agriculture and urban development
Inappropriately timed mowing
Trampling and agricultural activity

Current Research Summary
  Genetic analysis (using RAPD markers) of seven populations revealed low genetic diversity within populations (Kercher and Sytsma 2000). The same study also found that these genetic results did not reveal as many differences between populations as morphological data did.
Hannelore Artiomow, a graduate student at the University of Wisconsin-Milwaukee, is studying the influence of population size and plant density on pollinator visitation in this species (advisor Jeff Karron) (Artiomow ongoing 2002).
Dieringer (1999) studied the reproductive biology of A. skinneriana in two different populations (one with over 1000 individual plants and another with only a few hundred individual plants) in Illinois. He found that not only is this species capable of self-pollination, but that the rate of self-pollination among plants was higher in the small population than the large.
Judith Canne-Hilliker, at the University of Guelph, Ontario, Canada, has extensively studied the genus Agalinis, including the taxon A. skinneriana. Her studies include work on the chromosome numbers and taxonomy of Agalinis in North America, including A. skinneriana (haploid number n=13) (Canne 1983a).

Current Management Summary
  In Indiana, Hoosier Prairie Nature Preserve has a management plan for A. skinneriana (Trick 1995)
Most known populations of A. skinneriana are located on private land, and so in many cases they are not monitored, managed for, or protected. (Trick 1995)

Research Management Needs
  Information on population status needs to be collected, and the long-term health of known populations needs to be monitored.
Loss of genetic diversity and potential levels of inbreeding depression need to be further investigated.
Seed banking and seedling recruitment are also areas of research that need attention.
A comprehensive plan to protect populations of this species throughout its range is necessary to protect any genetic variation that remains in the species.

Ex Situ Needs
  Continue to maintain seeds in seed banks, and be sure that these seeds represent the full potential genetic diversity of the species.


Books (Single Authors)

1986. Flora of the Great Plains. Lawrence: University Press of Kansas.

2000. Missouri Plants of Conservation Concern. Jefferson City, MO: Conservation Commission of Missouri--Missouri Department of Conservation.

Brown, M.L.; Brown, R.G. 1984. Herbaceous plants of Maryland. Baltimore, MD: Port City Press, Inc.

Clewell, A.F. 1985. Guide to Vascular Plants of the Florida Panhandle. Tallahassee, Florida: Florida State University Press. 605p.

Correll, D.S.; Johnston, M.C. 1970. Manual of the vascular plants of Texas. Renner: Texas Research Foundation. 1881p.

Cronquist, A. 1981. An integrated system of classification of flowering plants. New York: Columbia University Press. 1262p.

Deam, C.M. 1984. Flora of Indiana. Indianapolis, Indiana: Division Forestry, Department of Conservation. 1236p.

Gleason, H.A. 1952. The New Britton and Brown illustrated flora of the northeastern United States and adjacent Canada. New York, NY: Hafner Press. 1732p.

Gleason, H.A.; Cronquist, A. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. Bronx: The New York Botanical Garden.

Gray, A.; Fernald, M.L. 1987. Gray's manual of botany: a handbook of the flowering plants and ferns of the central and northeastern United States and adjacent Canada. Portland, Or.: Dioscorides Press. 1632p.

Herkert, J.; Ebinger, J.E. 2002. Endangered and threatened species of Illinois: Status and distribution. Springfield, IL: Illinois Endangered Species Protection Board. 161p.

Lovell, J.H. 1918. The Flower and the Bee: Plant Life and Pollination. New York: Charles Scribner's Sons. 286p.

Mohlenbrock, R.H. 1986. Guide to the Vascular Flora of Illinois. Carbondale, Illinois: Southern Illinois University Press. 507p.

Pennell, F.W. 1935. The Scrophulariaceae Of Eastern Temperate North America. Philadelphia, Pennsylvania: Academy of Natural Sciences. 650p.

Pepoon, H.S. 1927. An Annotated Flora of the Chicago Region. Chicago, Illinois: The Chicago Academy of Sciences. 554p.

Radford, A.E.; Ahles, H.E.; Bell, C.R. 1968. Manual of the vascular flora of the Carolinas. Chapel Hill, NC: University of North Carolina Press. 1183p.

Smith, E.B. 1988. An Atlas and Annotated List of the Vascular Plants of Arkansas. Fayetteville: University of Arkansas. 489p.

Smith, J.P.; Berg, K. 1988. California native plant society's inventory of rare and endangered vascular plants of California. Sacramento: California Native Plant Society. 168p.

Steyermark, J.A. 1977. Flora of Missouri. Ames, IA: Iowa State University Press. 1728p.

Swink, F.; Wilhelm, G. 1994. Plants of the Chicago Region. Lisle, Illinois: The Morton Arboretum. 922p.

Books (Sections)

Kartesz, J.T. 1999. A synonymized checklist of the vascular flora of the U.S., Canada, and Greenland. In: Kartesz, J.T.; Meacham, C.A., editors. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden. Chapel Hill, NC.

Electronic Sources

(1994). Kansas Biological Survey Plant Database, R. L. Gregor Herbarium. Kansas Biological Survey.

(2002). Rare and Vulnerable Plant Species of Oklahoma. Oklahoma Natural Heritage Inventory. http://www.biosurvey.ou.edu/candhome.html. Accessed: 2002.

COSEWIC. (2001). Species at Risk. [Web site] Environment Canada; Committee on the Status of Endangered Wildlife in Canada. http://www.speciesatrisk.gc.ca/species/English/Default.cfm. Accessed: 2002.

OHDNR. (2001). Rare Native Ohio Plants: 2000-2001 Status List and Profiles. Ohio Division of Natural Areas and Preserves. http://www.dnr.state.oh.us/dnap/heritage/Rare_Species2000.htm. Accessed: 2002.

WIDNR. (2002). Wisconsin Endangered and Threatened Plants Species. Wisconsin Department of Natural Resources. http://www.dnr.state.wi.us/org/land/er/factsheets/00etlist2.htm. Accessed: 2002.

WIS. (2002). Wisconsin Vascular Plants--on species, including maps and photos. Wisconsin State Herbarium: University of Wisconsin - Madison (WIS). http://www.botany.wisc.edu/wisflora/. Accessed: 2002.

Journal Articles

Baird, W.V.; Riopel, J.L. 1984. Experimental studies of haustorium initiation and early development in Agalinis purpurea (l.) Raf. (Scrophulariaceae). American Journal of Botany. 71: 803-814.

Bentz, G.D.; Cooperrider, T.S. 1978. The Scrophulariaceae Subfamily Rhinanthoideae of Ohio. Castanea. 145-154.

Canne, J.M. 1979. A Light and Scanning Electron Microscope Study of Seed Morphology in Agalinis (Scrophulariaceae) and its Taxonomic Significance. Systematic Botany. 4, 4: 281-296.

Canne, J.M. 1981. Chromosome counts in Agalinis and related taxa (Scrophulariaceae). Canadian Journal of Botany. 59: 1111-1116.

Canne, J.M. 1983. The Taxonomic Significance Of Seedling Morphology In Agalinis (Scrophulariaceae). Canadian Journal of Botany. 61, 7: 1868-1874.

Canne, J.M. 1984. Chromosome numbers and the taxonomy Of North American Agalinis (Scrophulariaceae). Canadian Journal of Botany. 62, 3: 454-456.

Canne-Hilliker, J.M.; Dubrule, M.L. 1993. A new species of Agalinis (Scrophulariaceae) from Grimes County, Texas. Sida. 15, 3: 425-440.

Canne-Hilliker, J.M.; Kampny, C.M. 1991. Taxonomic significance of leaf and stem anatomy of Agalinis (Scrophulariaceae) from the U.S.A. and Canada. Canadian Journal of Botany. 69: 1935-1950.

Cooperrider, T.S. 1982. Endangered and Threatened Plants of Ohio. Biological Notes. 16: 1-92.

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

Fryxell, P.A. 1957. Mode of reproduction of higher plants. Botanical Review. 23, 3: 135-233.

Hays, J.F. 1998. Agalinis (Scrophulariaceae) in the Ozark Highlands. Sida. 18, 2: 555-577.

Kercher, S.M.; Sytsma, K.J. 2000. Genetic and morphological variation in populations of the rare prairie annual Agalinis skinneriana (Wood) Britton (Scrophulariaceae). Natural Areas Journal. 20, 2: 166-175.

Pennell, F.W. 1929. Agalinis and allies in North America--II. Proceedings Academy Natural Sciences Philadelphia. : 111-249.

Riopel, J.L.; Musselman, L.J. 1979. Experimental initiation of haustoria in Agalinis purpurea (Scrophulariaceae). American Journal of Botany. 66: 570-575.

USFWS. 1993. Review of plant taxa for listing as endangered or threatened species. Federal Register. 58, 188: 51144-51190.


Canne-Hilliker, J.M. 1987. Status report on Skinner's purple false foxglove Agalinis skinneriana (Wood) Britton an endangered species in Canada. Guelph, Ontario, Canada: Dept. of Botany, Univ. of Guelph.

Cusick, A.W. 1993. 1993 Status survey fo Skinner's foxglove, Agalinis skinneriana, in Ohio. Columbus, Ohio: Ohio Department of Natural Resources Division of Natural Areas and Preserves. p.11 pp + figures.

Dieringer, G. 1995?. Reproduction and Inbreeding in Agalinis skinneriana (Scrophulariaceae): Final Report. Springfield, IL: Western Illinois University, to the Illinois Department of Conservation.

Hays, J.F. 1995. A Missouri survey for Climbing Milkweed (Matelea baldwyniana (Sweet) Woodson) and Pale Gerardia (Agalinis skinneriana (Wood) Britton). Jefferson City, Missouri: Natural History Division, Missouri Department of Conservation. 14-45-0009-94-1019.

Hedge, C.; Homoya, M.C.; Baker, C. 1992. Report on the Status of Agalinis skinneriana (Pale False Foxglove) in Indiana. Indianapolis, Indiana: Indiana Department of Natural Resources, Division of Nature Reserves. p.12. Endangered Species Program Project: E-1-6, Study N.

Ostlie, W.R. 1990. Element Stewardship Abstract for Agalinis skinneriana, pale false foxglove. Arlington, VA: The Nature Conservancy. p.11.

Robertson, K.R.; Phillippe, L.R. 1993. The current status of Agalinis skinneriana (Wood) Britton in Illinois. Champaign, Illinois: Illinois Department of Conservation, Division of Natural Heritage. Research Project E-018-1.

Trick, J. 1994. Report on the Status of Pale False Foxglove, Agalinis skinneriana in Wisconsin, 1993. Green Bay, WI: U.S. Fish & Wildlife Service. p.6.

Trick, J. 1995. Range-wide status assessment of the pale false-foxglove Agalinis skinneriana (Wood) Brittonia. Green Bay, WI: U.S. Fish & Wildlife Service. p.26.

Trick, J. 1995. Report on the 1995 Field Activities Investigating the Status of Pale False Foxglove Agalinis skinneriana in Wisconsin. Green Bay, WI: U.S. Fish & Wildlife Service. p.5.

Trick, J.A. 1995. Report on the 1994 Field Activities Investigating the Status of Pale False Foxglove, Agalinis skinneriana, in Wisconsin. Green Bay, WI: U.S. Fish & Wildlife Service.

Watson, W.C. 1993. Iowa Inventory for Agalinis skinneriana (Wood) Britton, 1993 Final Report. Des Moines, Iowa: Iowa Field Office, The Nature Conservancy. Prepared for Iowa Department of Natural Resources.


Artiomow, Hannelore. ongoing 2002. The Influence of Population Size and Density on Pollinator Service in Agalinis skinneriana (Orobanchaceae). [M.S. Thesis]: University of Wisconsin-Milwaukee. Milwaukee, WI.

Snider, J. A. 1969. A Variation study of Agalinis decemloba (Greene) Pennell and Agalinis obtusifolia Raf. in the Carolinas. [Unpublished Master of Arts]: University of North Carolina at Chapel Hill. Chapel Hill, North Carolina.

Vincent, K.A. 1982. Scrophulariaceae of Louisiana. [M.S. thesis]: University of Southwestern Louisiana. Lafayette. 234p.

  This profile was updated on 3/4/2010
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