1.
Petasites frigidus
(Linnaeus) Fries, Summa Veg. Scand. 182. 1845.
Arctic sweet coltsfoot, Arctic butterbur
Tussilago frigida
Linnaeus, Sp. Pl. 2: 865. 1753;
Nardosmia frigida
(Linnaeus) Hooker
Plants
10—60(—120) cm.
Rhizomes
much branched, creeping, often forming long-lived, spreading clones.
Basal leaves:
blades mostly reniform, orbiculate-cordate, cordate, ovate, triangular, or sagittate, margins subentire to coarsely dentate to wavy, or shallowly to deeply pinnipalmately or palmately lobed, lobes obtuse to acute, often again lobed or toothed, abaxial faces densely white-tomentose to lanate, adaxial faces densely lanate or floccose, glabrescent, or glabrous.
Staminate heads
2—53 (ray florets: 0 or 1—70, styliferous and sterile, corolla laminae 1.1—12 mm; disc florets 11—78, functionally staminate; style branches 0—2.3 mm, papillate or hairy).
Pistillate heads
5—60 (ray florets 30—139, pistillate and fertile, corolla laminae 0.6—6.3 mm; disc florets 1—12, functionally staminate, style branches 0—2.3 mm, papillate or hairy).
Phyllaries:
staminate 3.6—12.8 × 1—4.4 mm, pistillate 1—9.5 × 0.7—3.3 mm, margins entire or serrate.
Cypselae
1.7—3.5 mm;
pappi
(longest, pistillate heads) 7—17.3 mm.
Varieties 4 (4 in the flora): North America, Eurasia.
