Senecio integerrimus

Perennials (possibly biennials), (10–)20–70 cm (caudices buttonlike, roots fleshy-fibrous). Herbage arachnose, loosely tomentose, or villous (hairs crisped, jointed), glabrescent. Stems single. Leaves progressively reduced distally; ± petiolate; blades elliptic, lanceolate, linear, oblanceolate, rounded-deltate, or suborbiculate, 6–25 × 1–6 cm, bases ± tapered or truncate to cordate, margins entire or ± dentate (distal leaves sessile, bractlike). Heads 6–20(–40+) in corymbiform arrays (peduncle of terminal head often shorter than others). Calyculi of 1–5+ linear to filiform bractlets (seldom more than 2 mm). Phyllaries usually ± 13 or ± 21, rarely ± 8, (4–)5–12(–15) mm, tips usually black, sometimes green. Ray florets usually ± 8 or ± 13, sometimes 0; corolla laminae 6–15(–20) mm (usually yellow, ochroleucous to white in one variety). Cypselae usually glabrous, sometimes hirtellous (mostly on angles). 2n = 40, 80.

Distribution

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Alta., B.C., Man., Sask., Calif., Colo., Idaho, Iowa, Kans., Minn., Mont., N.Dak., N.Mex., Nebr., Nev., Oreg., S.Dak., Utah, Wash., Wyo.

Discussion

Varieties 5 (5 in the flora).

The varieties of Senecio integerrimus are distinguished by morphology and geography.

Selected References

None.

Lower Taxa

Senecio integerrimus var. exaltatus, Senecio integerrimus var. integerrimus, Senecio integerrimus var. major, Senecio integerrimus var. ochroleucus, Senecio integerrimus var. scribneri

Key

1	Basal leaves with distinct petioles, blades usually ovate to rounded-deltate, sometimes obovate to oblanceolate; ray corollas white or ochroleucous	Senecio integerrimus var. ochroleucus
1	Basal leaves with or without distinct petioles, blades elliptic, lanceolate, oblanceolate, rounded-deltate, sublinear, or suborbiculate; ray corollas yellow (or rays 0)	> 2
2	Herbage glabrous or glabrate at flowering (except in leaf axils and among heads); phyllaries linear-subulate, tips usually green, minutely (if at all) black	Senecio integerrimus var. integerrimus
2	Herbage usually arachnose, tomentose, or villous at flowering; phyllaries lanceolate to linear-subulate, tips black (if minutely so, then narrowly lanceolate and broader than subulate)	> 3
3	Basal and proximal leaves oblong or lanceolate to sublinear; heads 3–6(–16+); phyllaries 10–15+ mm	Senecio integerrimus var. scribneri
3	Basal and proximal leaves mostly elliptic to oblanceolate, sometimes elliptic or rounded-deltate to suborbiculate; heads usually 6–15(–30+; if fewer than 6, leaves lanceolate or broader); phyllaries 5–12 mm.	> 4
4	Plants copiously arachnose, tomentose, or villous at flowering; phyllaries linear-subulate, 8–12 mm, tips minutely, if at all, blackened	Senecio integerrimus var. major
4	Plants copiously to sparsely arachnose, tomentose, or villous at flowering; phyllaries mostly lanceolate (seldom as narrow as linear-subulate), 5–10 mm, tips black	Senecio integerrimus var. exaltatus