The corolla changes from pink to blue as in Mertensia.

1. Upper leaves decurrent, with elongate narrow wings extending down the stem; calyx at anthesis ca. (5.5–) 6–9 mm long; pubescence spreading but not thorn-like; nutlets smooth and shiny between the ridges on the angles; connective between the anther sacs extending slightly beyond them.

S. officinale

1. Upper leaves not or scarcely (less than 1 cm) decurrent; calyx at anthesis ca. 3–4 mm long (soon elongating); pubescence of stem and inflorescence partly of strong recurved prickles or “thornlets” (± flattened and broad at base, like miniature rose prickles); nutlets papillose and coarsely reticulate between the angles; connective shorter than the anther sacs (the anthers appearing bifid at the apex).

S. asperum

All species found in Symphytum

Symphytum officinaleCOMMON COMFREY 


MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. March 29, 2017.