This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Tall biennial or perennial herbs, the stems simple, or branched at the base, with alternate dentate or entire leaves, and large showy purple yellowish or white flowers, in long terminal commonly 1-sided racemes. Calyx 5-parted, the segments imbricated. Corolla declined, somewhat irregular, the tube contracted above the ovary, then rather abruptly expanded, longer than the 4-5-lobed slightly 2-lipped limb; upper lip broadly emarginate or 2-cleft; lower lip 3-lobed, the middle lobe largest, the lateral ones exterior in the bud. Stamens 4, didynamous, ascending, mostly included; anthers approximate in pairs. Style slender; stigma 2-lobed. Capsule ovoid, septicidally dehiscent. Seeds numerous, rugose. [Latin, digitate, the finger of a glove, which the flowers resemble.]
About 20 species, native of Europe and Asia, the following typical.
Digitalis purpurea L. Sp. Pl. 621. 1753.
Usually biennial, pubescent; stem stout, erect, 2°-5° high. Basal and lower leaves ovate or ovate-lanceolate, 6'-10' long, slender-petioled, acute at the apex, narrowed at the base, dentate: upper leaves similar, smaller, sessile; racemes 1° long or more, dense, 1-sided; flowers purple to white, 1 1/2'-2' long, drooping; upper calyx-segment narrower than the four other foliaceous ones; corolla spotted within.
Cape Breton Island and New York, naturalized from Europe, sparingly escaped from cultivation; also from Washington to California. June-Aug. Among some 60 English names are folk's-glove [by corruption fox-glove], i.e., fairy's-glove, fairy-thimbles, -fingers, -weed, fairy-bells, pop-dock, or -glove. Rabbit's-flower. Cottagers. Lion's-mouth. Scotch mercury. Throatwort. Lady-fingers, -glove, -thimble. Dog's-finger. Witches'-thimbles.