Monographs Details: Hieracium
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 - Fls all ligulate and perfect, yellow to sometimes orange or red; invol cylindric to hemispheric, its bracts ± imbricate; achenes terete or prismatic, mostly narrowed below, truncate or occasionally narrowed toward the summit, ± strongly ribbed- sulcate; pappus of numerous whitish to more often sordid or brownish capillary bristles; fibrous- rooted perennial herbs from an elongate or very short rhizome (or mere crown), with milky juice, and alternate or all basal, entire or ± toothed lvs; heads in various sorts of infls, or solitary; most spp. with at least a few stellate hairs on the herbage or invol. (Pilosella) Thousands of names, perhaps hundreds of spp., mostly in temperate (or mountainous tropical) regions. Spp. 1–6 (all intr.) belong to a huge polyploid-apomictic complex without clear specific boundaries, and spp. 7–12 (some native, some intr.) to another. Spp. 13–18, all native, are diploid so far as known; they produce occasional hybrids, some of which have been named.