1. Symphytum officinale L. (common comfrey)

Map 1308, Pl. 310 a, b

Plants perennial herbs, with stout, somewhat fleshy taproots. Stems 30–1200 cm long, ascending or arched, solitary or more commonly few to several, unbranched or few- to several-branched below the inflorescence, moderately to densely pubescent with minute, spreading hairs often having microscopically hooked tips and also sparse to moderate longer, stiff, spreading to somewhat downward-curved, usually strongly pustular-based hairs. Leaves alternate and basal, the basal leaves mostly with long, usually winged petioles, the stem leaves mostly short-petiolate, the upper leaves sometimes sessile, the bases mostly extending down the stem as wings, these often narrow. Leaf blades 4–35 cm long, 15–150 mm wide, ovate to elliptic, those of the uppermost leaves sometimes lanceolate, tapered at the base, tapered to a sharply pointed tip, the upper surface roughened-pubescent with shorter and longer, stiff, spreading, usually strongly pustular-based hairs, the shortest of these often minutely hooked at the tip, the undersurface moderately to densely hairy with short, soft, curved hairs, with usually 4–7 noticeable pairs of lateral veins (these arched, forming a faint network). Inflorescences not paired, terminal on the branches, appearing as dense clusters at the start of flowering, then becoming slightly elongated into short, more or less scorpioid, spikelike racemes with often pendant flowers, these continuing to elongate as the fruits mature, sometimes appearing aggregated into leafy panicles, the flowers with stalks 2–10 mm long, these elongating to 4–15 mm at fruiting, usually spreading to drooping, the flowers lacking bracts. Cleistogamous flowers not produced. Calyces actinomorphic or nearly so, 5-lobed about 3/4 of the way to the base, the lobes 3–6 mm long at flowering, elongating to 5–10 mm at fruiting, narrowly triangular to nearly linear, densely pubescent with minute, spreading hairs having microscopically hooked tips and scattered, longer, stiff, spreading, pustular-based hairs, persistent and ascending at fruiting. Corollas 12–18 mm long, narrowly funnelform to narrowly bell-shaped, actinomorphic, purple to dull purplish blue (rarely cream-colored to pale lemon yellow elsewhere), the tube 6–12 mm long, the throat with small, scalelike appendages, the lobes often spreading to outward-curled, 1–2 mm long. Stamens inserted near the midpoint of the corolla tube, the filaments relatively short (shorter than the anthers), the anthers oblong, not exserted from the corolla. Ovary deeply 4-lobed, the style elongate, twisted just below the tip, exserted slightly from the corolla, usually somewhat withered but persistent at fruiting, the stigma capitate, unlobed. Fruits dividing into mostly 4 nutlets, these 4–6 mm long, erect or ascending, more or less angular-ovoid with a blunt ventral keel, attached to the relatively flat gynobase at the base or nearly so, the attachment scar surrounded by a low, collarlike ring with an irregularly toothed margin, mostly bluntly pointed at the somewhat oblique tip, the surface smooth, black, shiny. 2n=24, 32, 40–48, 56. June–August.

Introduced, uncommon and sporadic, thus far mostly in the eastern half of the state (native of Europe, introduced nearly throughout the U.S., Canada). Roadsides and disturbed areas.

Comfrey once was grown widely for animal feed, being very rich in minerals and protein, and the young leaves have been used by humans in teas and salads. It also has a long history of medicinal use, often taken in the form of teas, extracts, and poultices. The lengthy register of putative uses includes treatment in various types of applications for lung diseases, diarrhea, colds, gangrene, burns, anemia, ulcers, wounds, headaches, tuberculosis, bee stings, insect bites, and broken bones (Al-Shehbaz, 1991). However, the presence of pyrrolizidine alkaloids and potential liver toxicity makes Symphytum species a potential health risk for human consumption (Burrows and Tyrl, 2001).