Similar species: Symphytum asperum is very similar to S. Roots: branching, thickened, and secreting a sticky, bitter, gelatinous substance (mucilage). The basal stalk-like structure of each nutlet fits into a central pit of the otherwise flattish base of the remnant flower, thereby holding the nutlets at a slight upward angle with the tips pointing toward the center. Fruit: a cluster of four, rough, wrinkled, approximately 4 mm tall, somewhat egg-shaped, incurved nutlets with a lengthwise ridge on the inner side, and a prominent toothed basal rim surrounding a short, stalk-like, basal appendage.

The style and stigma are just longer than the petal tube. Pistil: with one, four-lobed, two-chambered, superior ovary and a single, slender, threadlike style with a single stigma. Stamens: five, filaments narrower than anthers, very short, attached to top inside of petal tube, but anthers never extended beyond petal tube. Petals: five, but fused into a long cylindric tube for most of their length, then separating into five, tooth-like lobes which are much shorter than the tube portion. After flowering the calyx elongates to 1 - 1.7 cm long in fruit. Sepals: bristly and prickly-hairy, five, but fused at base, then separating into 2.5 - 4 mm long, somewhat lance-shaped, obviously pointed lobes. Flowers: pink turning blue, 1 - 1.5 cm tall, radially symmetric, narrowly bell-shaped with long, cylindric petal tube, and very short, erect, tooth-like lobes. Inflorescence: of several to many, often paired, nodding, stout, short, prickly-spiny, modified spike-like branches near top of stem and often in upper leaf axils, with individual flowers stalked. Leaves: alternate, mostly stalkless (rarely with leaf tissue continuing down the stem), non-toothed, harshly prickly-hairy, large (over 6 cm long and wide), somewhat egg-shaped or lance-shaped, usually longer than wide. Perennial herb 30 cm - 1.5 m tall Stem: stout, branching, covered with very prickly, stout, flattened, recurved, and spiny hairs with broad bases similar to tiny rose thorns.