The Friends of the Wildflower Garden, Inc.
Plants of the Eloise Butler Wildflower Garden
The oldest public wildflower garden in the United States
Common Name
Grecian Foxglove (Woolly Foxglove, Digitalis)
Scientific Name
Digitalis lanata Ehrh.
Plant Family
Plantain (Plantaginaceae)
Garden Location
Upland
Prime Season
Early Summer to Autumn Flowering
Grecian Foxglove is a non-native biennial/perennial plant in the United States (native to Europe, particularly Greece, and North Africa) that has become naturalized in a number of areas. Most Digitalis lanata are biennial but some can be perennial if the growing season is longer. In the plants first year it forms a basal rosette and in second and subsequent years sends up an unbranched smooth flowering stem that can reach 2 to 5 feet in height and have purplish coloration or blotches.
Leaves: The first year growth produces a basal rosette of dark green leaves. Leaves on the second year plant are sessile (no stalks), alternate, linear or slightly broader below the middle, with pointed tips, up to 6 inches long, and entire margins. They have hair near the point of attachment to the stem and on the underside.
The inflorescence is a tall spike, a raceme, very hairy, with the flowers surrounding the spike, not just on one side like many other Digitalis species. The stately flower spikes are a stand-out in early summer if allowed to grow.
The flowers are perfect, 5-parted with a tubular corolla of five united petals, cream white to pale yellow or yellow-brown, with many purplish-reddish veins inside and a large white lower lip, that reflexes downward, the edges of which are hairy. The top of the corolla has a distinct ridge line. The 4 stamens are in pairs with one pair longer than the other. The style has a 2-lobed stigma and rises from a 2-locular ovary. All reproductive parts are entirely contained within the corolla. The flower can self-fertilize. The green calyx is short, 8 to 10 mm long, compared to the corolla tube. It has five linear long pointed lobes and all parts of the calyx are hairy. Each flower is subtended by a green leaf-like bract.
Seed: Fertile flowers produce a ovoid dry seed capsule containing numerous small brown to black kidney shaped seeds. Each plant has a large number of seed capsules which have small hooks which attach to fur or clothing allowing the seeds to be dispersed widely.
Toxicity: Like most species in the Digitalis family, the plant contains chemicals that are dangerous to browsing animals and humans (see notes below the photo section).
Invasive: Grecian Foxglove is a prohibited noxious weed on the 'eradication' list in Minnesota.
Habitat: Grecian Foxglove grows best in hot dry sites, accepts a wide variety of soils and tolerates a lot of sun but partial shade is preferred. It spreads solely by seed. The flower spike will re-sprout when cut. For control aspects see bottom of page. Plants that have been trimmed back during the growing the season may put up a short flower spike in the fall.
Names: For many years D. lanata was assigned to the Figwort (Scrophulariaceae) family. It has recently been reclassified into the Plantain family (Plantaginaceae) due to phylogenetic studies conducted by the Angiosperm Phylogeny Group. The genus name, Digitalis, is derived from the Latin digitus, meaning 'finger'. That word was chosen as a derivation of the German word for Foxglove, which is Fingerhut, meaning a 'finger hat' - i.e. the 'glove' part reflects the similarity of the Foxglove blossom to the fingers of a glove (a 'finger hat'). The species name, lanata, means 'woolly' in Latin. The author name for the plant classification - ‘Ehrh.', refers to Jokob Friedrich Ehrhart (1742-1795), German botanist, pupil of Linnaeus, director of the Botanical Garden of Hannover and the first author to use subspecies in botanical literature. The other common name of Digitalis refers to the heart medicine, digitalis, that is produced from this species.
Comparisons: A close relative is the Garden, or Common Foxglove, Digitalis purpurea, which is not considered invasive and has longer stalked flowers that are more rosy, spotted inside, not veined, a much smaller lower lip and the leaves are coarsely toothed.
Above and Below: The flowers have a corolla of 5 united petals that taper abruptly to the hairy green calyx. The lower lip is extended and pure white, covered with fine hair. All reproductive parts are contained within the corolla tube.
Below: The inflorescence, flower stalks, lower lip of the flower, leaf edges where they meet the stem - all have hair. The leaf is sessile (not stalked).
Below: 1st photo - Details of the long hair in the inflorescence. 2nd photo - the remaining prior year leaves of the basal rosette.
Below: The stately spires of Grecian Foxglove growing in groups on the hillside in early July are quite attractive, if only it weren't so invasive and toxic.
Garden Control procedures: The plant was not listed on Martha Crone's inventory of plants in the Garden in 1951 and had arrived in the Garden sometime before 1986. Garden staff and Legacy Stewards have, for several years now, maintained control measures to remove new growth before flower maturity. It may be some years before the seed bank in the soil is exhausted.
Noxious Plant Notes: Grecian Foxglove is not native to Minnesota or to North America but introduced from Europe where it is indigenous to the western and central parts. It is generally restricted to the states bordering the Great Lakes plus New England and to several of the mid-continent cropland states such as Nebraska and Kansas. The plant seed capsules have small hooks which attach to fur or clothing allowing the seeds to be dispersed widely. As such, it is considered a threat to native savanna and prairie plant communities. Grecian Foxglove is listed on the DNR's Minnesota invasive non-native terrestrial plant list as a prohibited noxious weed. Eradication is by pulling or spot application of glyphosate. The MN DNR has experimented with chemical control and determined the most effective chemical was Msm (Metsulfron methyl). Typical homeowner available formulations such as Triclopyr and Mecoprop are not effective. Glyphosate works but does not touch the seedbank. All chemicals can be avoided by cutting the flowering stem before seeds set, and doing the same until the seed bank is exhausted. (DNR report- pdf)
Toxicity: The chemical makeup of the plant is toxic to humans and animals, although the heart medicine, digitalis, is a derivative of this species and D. purpurea. The species contains the cardiac glycosides digoxin (digitalin) and digitoxin. Symptoms of digitalis poisoning include nausea, vomiting, severe headache, dilated pupils, and convulsions. Most reported cases of severe toxicity have been in wild food gatherers mistaking the plant for Comfrey. In controlled use the glycosides have been very beneficial in treating heart conditions, asthma, and wound treatment. Digitoxin is still obtained from the plant because synthesis of the chemical is very expensive, however, some uses are being replaced by the newer class of drugs such as beta blockers, calcium channel blocking agents and others. Similar glycosides are obtained from the Garden Foxglove, D. purpurea. This pdf (Article) from the British Heart Journal of 1985 explains how large amounts of D. lanata where produced and processed in the Netherlands following the Second World War.
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References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
©2014
Friends of the Wildflower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofeloisebutler.org"
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