Monographs Details: Petasites
Authority: Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Description:Genus Description - Subdioecious; heads of male plants with the fls all tubular and functionally staminate, or sometimes with a few outer pistillate fls like those of the female heads; heads of female plants with the fls all pistillate and fertile, or sometimes with a few central functionally staminate fls; pistillate fls with tubular-filiform cor, the outer ones sometimes provided also with a ligule; invol a single series of equal, ± herbaceous bracts, sometimes with a few basal bracteoles; receptacle flat, naked; achenes linear, 5–10-ribbed; pappus of numerous capillary bristles, elongating in fr, that of the sterile fls ± reduced; ± white-tomentose or woolly perennial herbs with large basal lvs, merely bracteate stems (the bracts alternate), and several or many medium- sized, purple, white, or rarely yellowish heads, flowering before the lvs expand. 15, N. Hemisphere.