Digitalis

Herbs [shrubs], biennial or perennial. Stems erect, simple or branching from base, glabrous, glabrate, pilose, or villous. Leaves basal and cauline, alternate, smaller distally; petiole absent [present]; blade not fleshy, not leathery, margins entire or serrate to coarsely doubly serrate. Inflorescences terminal, racemes, often secund; bracts present. Pedicels present; bracteoles usually absent. Flowers bisexual; sepals 5, distinct, narrowly triangular to lanceolate or ovate-lanceolate, calyx ± bilaterally symmetric, campanulate; corolla brown, yellow, pink to purple, or white, bilaterally symmetric, ± bilabiate, funnelform, tubular-funnelform, or globular to ovoid, tube base not spurred or gibbous, lobes 5, abaxial 3, adaxial 2; stamens 4, adnate to corolla, didynamous, filaments glabrous or hairy; staminode 0; ovary 2-locular, placentation axile; stigma 2-lobed or punctiform. Fruits capsules, dehiscence septicidal, sometimes secondarily loculicidal. Seeds 20–60, brown to black, prismatic or cylindric to ovoid, wings absent. × = 28.

Distribution

Europe, w Asia, introduced also nearly worldwide.

Discussion

Species 22 (4 in the flora).

All species of Digitalis are poisonous, containing cardiac glycosides including digitoxin. In addition to the following species, D. ferruginea Linnaeus is sometimes found in cultivation in North America. It has yellow to yellow-brown corollas, like D. lanata, but the corolla tubes are elongate, not globular.

Selected References

Aronson, J. K. 1986. An Account of the Foxglove and Its Medicinal Uses, 1785–1985. Oxford.

Werner, K. 1965. Taxonomie und Phylogenie der Gattungen Isoplexis Lindl. und Digitalis L. Repert. Spec. Nov. Regni Veg. 70: 109–135.

Lower Taxa

Digitalis grandiflora, Digitalis lanata, Digitalis lutea, Digitalis purpurea

Key

1	Corolla tubes globular to ovoid; leaf blade margins entire.	Digitalis lanata
1	Corolla tubes funnelform or tubular-funnelform; leaf blade margins serrate or serrate at least distally.	> 2
2	Corolla tubes 13–15 mm; throats 5–7 mm diam.	Digitalis lutea
2	Corolla tubes 25–60 mm; throats 14–25 mm diam.	> 3
3	Corolla tubes pale yellow; leaf blade margins finely and evenly serrate distally.	Digitalis grandiflora
3	Corolla tubes purple-pink to white; leaf blade margins coarsely serrate.	Digitalis purpurea