|Photo by Catherine Herms, The Ohio State University, Bugwood.org|
|Division:||Magnoliophyta - Flowering plants|
|Class:||Magnoliopsida - Dicotyledons|
|Natural range of Aureolaria pedicularia from USDA NRCS Plants Database.|
Common name: Fernleaf yellow false foxglove, annual oak-leech
Synonyms: Gerardia pedicularia Linnaeus var. pedicularia
Varieties: Gerardia pedicularia Linnaeus var. austromontana (Pennell) Fernald; Gerardia pedicularia Linnaeus var. intercedens (Pennell) Fernald
In the genus Aureolaria, the plants are either annual or perennial. They are parasitic on the roots of Quercus (oaks) and turn black when dried. The leaves are opposite or subopposite and branch from the upper portion of the stem (cauline). The flowers are showy, the calyx is 5-parted, the lobes can be shorter or longer than the tube. The flower is yellow in color, bilabiate, and 5-parted. The tube is bell-shaped with spreading lobes. There are 4 stamens, didynamous, and the filaments are flattened with the 2 longer more or less lanose. The anther sacs are basally awned. The stigma is capitate and protruding.
Specifically, A. pedicularia is an annual, growing up to 1 m tall and is profusely branched and pubescent. The stems are glandular-pubescent below, but not above. They are parasitic to Quercus velutina (black oaks). The basal rosette leaves are elliptic-lanceolate to rhombic, are entire or irregularly crenate-serrate, and approximately 4 - 8 cm long, 1.5 - 3 cm wide. The upper stem leaves are lanceolate, entire or bipinnately lobed to parted, the divisions are angulate and sometimes serrate puberulent to pubescent, the trichomes are not glandular, and grow to approximately 2 - 6 cm long, 8 - 21 cm wide. The flowers are axillary and solitary. The pedicels are 8 - 16 mm long, the pedicels and calyx tubes are glandular-pubescent. The calyx lobes are usually folios, the calyx lobes are longer than the tube. The flower is 3 - 4.5 cm long and 3 - 4 cm broad. The capsule is ellipsoid and 8 - 10 mm long; the lower half is enclosed in the calyx tube. The seeds are wingless.
In its northern range, A. pedicularia is a biennial plant that forms a basal rosette of leaves in late summer and bolts the following spring while in the southern range it is an annual. The stem is terete and covered with glandular hairs. The leaves are fernlike, opposite and sessile.
A. pedicularia can occur in slash pinelands, oak-hickory forests, and oak-pine forests. Large populations have been observed on road banks, powerline corridors and other disturbed areas. The inclination for disturbed areas and prolific seed production allows a strong potential as a forest plantation pathogen. Associated species include Pinus rigida, Castanea pumila, Pinus palustris and species of Quercus. It is a hemiparasitic plant, with a strong affinity for oaks. In Musselman's 1969 study, he suggested that A. pedicularia was specific to oak species, however studies have shown populations growing without oaks hosts. Werth suggested that it does not exhibit a promiscuous parasitism characteristic, but a selectivity for fagaceous roots.
A. pedicularia was found to decrease its occurrence or become absent in response to soil disturbance by agriculture in southwest Georgia. It has also shown resistance to regrowth in reestablished pinelands that were disturbed by agriculture.
This species is thought to be dispersed by wind.
Seed bank and germination
The germination of A. pedicularia is epigeal, with the radicle having a strong geotropic response. The radicles are covered with root hairs however, seedlings do not have root hairs, this phenomenon could be the result of vestigial characteristics. Germination does not depend on light.
Three types of bumblebees are responsible for pollination: Bombus impatiens, B. vagans and B. affinis. B. affinis is a nectar robber, cutting holes in the base of the corolla tubes to obtain nectar.
Herbivory and toxicology
Larva of the Orange Sallow moth (Pyrrhia aurantiago) feed on the flower, developing seeds and foliage in early October.
Conservation, cultivation, and restoration
A. pedicularia should avoid soil disturbance by agriculture to conserve its presence in pine communities.
References and notes
- Weakley, A.S. 2020. Flora of the Southeastern United States. Edition of 20 October 2020. University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
- Radford, Albert E., Harry E. Ahles, and C. Ritchie Bell. Manual of the Vascular Flora of the Carolinas. 1964, 1968. The University of North Carolina Press. 957-8. Print.
- Musselman, L. J. (1969). "Observations on the life history of Aureolaria grandiflora and Aureolaria pedicularia (Scrophulariaceae)." American Midland Naturalist 82: 307-311.
- Musselman, L. J. and W. F. Mann, Jr (1978). Root parasites of southern forests. , USDA Forest Service, Southern For. Exp. Station, New Orleans, LA. Gen. Tech. Rpt. SO-20. : 76.
- [Illinois Wildflowers]Accessed: November 30, 2015.
- [Minnesota Department of Natural Resources] Accessed: November 30, 2015
- Florida State University Robert K. Godfrey Herbarium database. URL: http://herbarium.bio.fsu.edu. Last accessed: October 2015. Collectors: Robert K. Godfrey. States and Counties: Florida: Wakulla. Compiled by Tall Timbers Research Station and Land Conservancy
- Stiles, Edmund W.. Foraging Behavior of Bumblebees on False Foxglove. Journal of the New York Entomological Society 85.4 (1977): 249–252.
- Werth, Charles R., and James L. Riopel. A Study of the Host Range of Aureolaria Pedicularia (L.) Raf. (Scrophulariaceae). American Midland Naturalist 102.2 (1979): 300–306.
- Musselman, L. J. and H. E. Grelen (1979). "Population of Aureolaria=Pedicularia (L) Raf (Scrophulariaceae) without oaks." American Midland Naturalist 102(1): 175-177.
- Ostertag, T. E. and K. M. Robertson. 2007. A comparison of native versus old-field vegetation in upland pinelands managed with frequent fire, South Georgia, USA. Tall Timbers Fire Ecology Conference Proceedings 23: 109-120.
- Nelson, G. PanFlora: Plant data for the eastern United States with emphasis on the Southeastern Coastal Plains, Florida, and the Florida Panhandle. www.gilnelson.com/PanFlora/ Accessed: 19 MAY 2021
- Kirkman, L. Katherine. Unpublished database of seed dispersal mode of plants found in Coastal Plain longleaf pine-grasslands of the Jones Ecological Research Center, Georgia.
- [Rare Plants of New Hampshire] Accessed December 1, 2015
- [Natural Heritage and Endangered Species Program]Accessed December 1, 2015