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Mount Sheldon butterweed, Mount Sheldon ragwort, Mt. Sheldon ragwort

alkali marsh groundsel, alkali-marsh butterweed, alkali-marsh ragwort, water groundsel, water ragwort

Habit Perennials, 30–40(–50) cm (caudices branched, fibrous-rooted). Perennials (biennials?), 40–100(–200) cm (caudices foreshortened, roots fleshy-fibrous).
Herbage

glabrous or with scattered hairs near leaf bases and among heads.

(often sea-green, usually glaucous) glabrous.

Stems

single or loosely clustered.

single or 2–4 loosely clustered.

Leaves

evenly distributed;

petiolate or subsessile;

blades lanceolate, 4–10 × 2–4 cm, bases ± tapered, margins denticulate (distal leaves sessile, smaller).

progressively reduced distally; ± petiolate;

blades elliptic to oblanceolate, 5–20+ × (1–)2–10 cm, bases tapered, margins denticulate or entire (mid and distal leaves sessile, bractlike).

Ray florets

± 8;

corolla laminae ± 10 mm.

(0) ca. 5;

corolla laminae 3–5 mm.

Phyllaries

± 13, 7–10 mm, tips black (hairy).

± 8 or ± 13, 5–8 mm, tips frequently black.

Calyculi

of 3–7 bractlets (0.5–3 mm).

of 2–4+ bractlets (less than 2 mm).

Heads

(1–)3–5(–6) in cymiform arrays.

20–40(–80+) in compound corymbiform arrays.

Cypselae

glabrous.

glabrous.

2n

= 40.

Senecio sheldonensis

Senecio hydrophilus

Phenology Flowering late Jul–mid Aug. Flowering spring–early summer.
Habitat Subalpine meadows and valleys Marshes, swampy places, standing water, alkaline sites
Elevation 1200–1800 m (3900–5900 ft) (0–)200–2500 m ((0–)700–8200 ft)
Distribution
from FNA
BC; NT; YT
[BONAP county map]
from FNA
CA; CO; ID; MT; NV; OR; SD; UT; WA; WY; BC
[WildflowerSearch map]
[BONAP county map]
Discussion

Senecio sheldonensis is infrequently collected and poorly understood. The treatment here is provisional.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 20, p. 567. FNA vol. 20, p. 557.
Parent taxa Asteraceae > tribe Senecioneae > Senecio Asteraceae > tribe Senecioneae > Senecio
Sibling taxa
S. actinella, S. amplectens, S. ampullaceus, S. aphanactis, S. arizonicus, S. aronicoides, S. astephanus, S. atratus, S. bigelovii, S. blochmaniae, S. californicus, S. cannabifolius, S. clarkianus, S. crassulus, S. elegans, S. elmeri, S. eremophilus, S. ertterae, S. erucifolius, S. flaccidus, S. fremontii, S. hydrophiloides, S. hydrophilus, S. integerrimus, S. jacobaea, S. lemmonii, S. lugens, S. lyonii, S. megacephalus, S. mohavensis, S. multidentatus, S. neowebsteri, S. parryi, S. pattersonensis, S. pseudoarnica, S. pudicus, S. quaylei, S. rapifolius, S. riddellii, S. sacramentanus, S. scorzonella, S. serra, S. soldanella, S. spartioides, S. sphaerocephalus, S. spribillei, S. squalidus, S. sylvaticus, S. taraxacoides, S. triangularis, S. viscosus, S. vulgaris, S. warnockii, S. wootonii
S. actinella, S. amplectens, S. ampullaceus, S. aphanactis, S. arizonicus, S. aronicoides, S. astephanus, S. atratus, S. bigelovii, S. blochmaniae, S. californicus, S. cannabifolius, S. clarkianus, S. crassulus, S. elegans, S. elmeri, S. eremophilus, S. ertterae, S. erucifolius, S. flaccidus, S. fremontii, S. hydrophiloides, S. integerrimus, S. jacobaea, S. lemmonii, S. lugens, S. lyonii, S. megacephalus, S. mohavensis, S. multidentatus, S. neowebsteri, S. parryi, S. pattersonensis, S. pseudoarnica, S. pudicus, S. quaylei, S. rapifolius, S. riddellii, S. sacramentanus, S. scorzonella, S. serra, S. sheldonensis, S. soldanella, S. spartioides, S. sphaerocephalus, S. spribillei, S. squalidus, S. sylvaticus, S. taraxacoides, S. triangularis, S. viscosus, S. vulgaris, S. warnockii, S. wootonii
Synonyms S. hydrophilus var. pacificus
Name authority A. E. Porsild: Canad. Field-Naturalist 64: 43. (1950) Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 411. (1841)
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