Family: Sorophulariaceae, Digitalis species
Source: Simon, J.E., A.F. Chadwick and L.E. Craker. 1984.
Herbs: An Indexed Bibliography. 1971-1980. The Scientific Literature
on Selected Herbs, and Aromatic and Medicinal Plants of the Temperate
Zone. Archon Books, 770 pp., Hamden, CT.
Foxglove is the common name for plants of the Digitalis
species, primarily represented by common foxglove, Digitalis
purpurea L., and Grecian foxglove, Digitalis lanata
J. F. Ehrh. These biennial or perennial plants, native to the
Mediterranean region, reach heights of 1.2 to 2 meters. The plants
have lanoeolate to ovate leaves and showy bell-shaped flowers
in racemes. Foxglove, almost always produced under commercial
contract, has traditionally been grown in Germany, England, India,
and several eastern European countries.
The reported life zone for common foxglove is 6 to 21 degrees
centigrade with an annual precipitation of 0.3 to 2.1 meters and
a soil pH of 4.5 to 8.3 (4.1-31). The hardy, easy to grow
plant flourishes in well-drained loam soil. Because of the
small seed size and nonuniform germination of the typical heterogenous
seed lots, plants are usually transplanted into the field to obtain
the desired plant density. Leaves are harvested late in the first
fall or in the following spring. Plants are dried in the shade
or with artificial heat. Exposure to sunlight or moisture decreases
the medicinal value of the leaves.
There are many natural, secondary, and other derived compounds
from Digitalis species. The important cardenolides or cardiac
glycosides include digitoxin, digoxin, gitoxin, from the lanatosides
A, B, and C, and from purpurea glycoside A and B. The important
saponins include digitonin, tigonin and gitonin. Additional medicinally
useful steroids and cortical hormones can be made from the plant
steroids. The glycoside content of tissue varies with the individual
plant, the stage of development, the growth environment, and the
time and method of harvest. Comfrey leaves have been reported
to be used as an adulterant (11.1-50).
There are several varieties of ornamental foxglove available,
differing in size and flower color. The primary value of foxglove,
however, is as a source of the medicinally important glycosides
found in the plant. Digitalis, a cardiovascular drug extracted
from the leaves, is the most effective drug available for heart
failure caused by hypertension or arteriosclerosis (11.1-96).
It is also used medicinally as a heart regulator, a diuretic,
and an expectorant. Digoxin and lanatoside C from foxglove are
effective in the correction of arrhythmias (11.1-95). Folk
remedies use foxglove as a cardiac tonic and in the treatment
of circulatory failures (11.1-154). The cardenolides slow
and strengthen the heart beat.
Digitalis is poisonous, and symptoms include vomiting, headache,
irregular heartbeat, and convulsions (11.1-96). Overdoses
can be fatal.
Several wild strains and cultivated varieties of foxglove exist
and are collected or produced for their ornamental and medicinal
[Note: References listed above in parentheses can be found in
full in the original reference].
Last modified 6-Dec-1997