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..
Erect coarse hairy perennial branching herbs, with thick mucilaginous roots, alternate entire leaves, those of the stem mostly clasping, the uppermost tending to be opposite, the lower long-petioled. Flowers yellow, blue, or purple, in terminal simple or forked scorpioid racemes. Calyx deeply 5-cleft. Corolla tubular, slightly dilated above, 5-toothed or 5-lobed, the lobes short, the throat with 5 crests below the lobes. Stamens 5, included, inserted on the corolla-tube; filaments slender. Ovary 4-divided; style filiform. Nutlets 4, obliquely ovoid, slightly incurved, wrinkled, inserted by their bases on the flat receptacle, the scar of the attachment broad, concave, dentate. [Greek, grow-together, from its supposed healing virtues.]
About 15 species, natives of the Old World. Type species: Symphytum officinale L. Leaf-bases decurrent.
1. S. officinale.
Leaf-bases not decurrent, or but slightly decurrent.
2. S. aspemmum.
Symphytum officinale L. Sp. Pl. 136. 1753.
Roots thick, deep; stem erect, branched, 2°-3° high. Leaves lanceolate, ovate-lanceolate, or the lower ovate, pinnately veined, 3-10' long, acute or acuminate at the apex, narrowed into margined petioles, or the uppermost smaller and sessile, decurrent on the stem; petioles of the basal leaves sometimes 12' long; flowers numerous, in dense racemes or clusters; pedicels 2"-4" long; calyx-segments ovate or ovate-lanceolate, acute or acuminate, much shorter than the corolla; corolla yellowish or purplish, 6"-10" long; nutlets brown, shining, slightly wrinkled, 2" high.
In waste places, Newfoundland to Minnesota, south to Virginia and North Carolina. Naturalized or adventive from Europe. Native also of Asia. June-Aug. Back- or black-wort. Bruisewort. Knit-back. Boneset. Consound. Gum-plant.
Symphytum tuberosum L., with thickened tuberous roots, the nutlets granular-tuberculate, not shining, has been found in sandy meadows in Connecticut.
S. asperrimum Donn; Sims, Bot. Mag. 24: pl. 929. 1806.
Similar to S. officinale, but the pubescence rougher, the hairs stiff and reflexed. Leaves ovate-lanceolate to oblong-lanceolate, long-acuminate at the apex, narrowed at the base, all but the uppermost petioled, slightly or not at all decurrent, the lower often 8' long; flower-clusters rather loose; calyx about half as long as the corolla-tube, its segments hispid; corolla bluish-purple.
Waste grounds, Massachusetts to Maryland. Ad-ventive or naturalized from Europe. June-Aug.