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lambstongue ragwort, western groundsel

alkali marsh butterweed, water groundsel

Habit Herbs perennial or biennial, (1)2–7 dm; caudices button-like, with fleshy, fibrous, unbranched roots. Herbs perennial or biennial, 4–10(20) dm; caudices short and button-like, with fleshy, fibrous, unbranched roots.
Stems

1, loosely arachnoid-tomentose, or villous, glabrate with age.

1, or 2–4 and loosely clustered, often bluish green, usually glaucous and glabrous.

Leaves

mostly basal;

cauline progressively reduced distally; ± petiolate;

basal and lower cauline elliptic, lanceolate, linear, oblanceolate, rounded-deltate, rarely suborbiculate, bases tapered or truncate to cordate;

margins entire or dentate;

distal becoming sessile and bract-like.

progressively reduced distally; thick; fleshy-turgid;

basal and lower cauline elliptic to oblanceolate, bases tapered;

margins entire to denticulate; ± petiolate; middle and upper cauline bract-like;

surfaces glaucous, sessile.

Inflorescences

corymb-like arrays;

bracts 0 or inconspicuous.

compound corymb-like arrays;

bracts 0.

Involucres

urn-shaped.

cylindric or narrowly urn-shaped.

Ray florets

5, rarely 0;

rays 6–15(20) mm, yellow or white to pale yellow.

5, sometimes 0;

rays 3–5 mm.

Disc florets

35–45.

20–35.

Phyllaries

(8)13 or 21;

tips usually black, sometimes green.

8 or 13, 5–8 mm;

tips usually black.

Calyculi

1–5+, inconspicuous, usually < 2 mm.

2–4+ bractlets, inconspicuous, usually < 2 mm.

Fruits

2.5–3 mm, usually glabrous, sometimes hairy along ribs.

2.5–3 mm, glabrous.

Heads

6–15(30+).

20–40(80).

2n

=40, 80.

=40.

Senecio integerrimus

Senecio hydrophilus

Distribution
[WildflowerSearch map]
[BONAP county map]
[WildflowerSearch map]
[BONAP county map]
Discussion

Western North America. 5 varieties; 3 varieties treated in Flora.

Standing water in marshes, swampy places, alkaline sites. Flowering Jun–Aug. 0–2100 m. BR, BW, Casc, CR, ECas, Lava, WV. CA, ID, NV, WA; north to British Columbia, northeast to MT, east to SD, southeast to CO. Native.

Senecio hydrophilus and S. hydrophiloides can be very difficult to distinguish on herbarium specimens. There are, however, significant ecological differences, with the former species restricted to alkaline soils and the latter found in damp but not alkaline places.

Source Flora of Oregon, volume 2, page 339
Debra Trock
Flora of Oregon, volume 2, page 339
Debra Trock
Sibling taxa
S. aronicoides, S. crassulus, S. ertterae, S. fremontii, S. hydrophiloides, S. hydrophilus, S. jacobaea, S. serra, S. sphaerocephalus, S. sylvaticus, S. triangularis, S. viscosus, S. vulgaris
S. aronicoides, S. crassulus, S. ertterae, S. fremontii, S. hydrophiloides, S. integerrimus, S. jacobaea, S. serra, S. sphaerocephalus, S. sylvaticus, S. triangularis, S. viscosus, S. vulgaris
Subordinate taxa
S. integerrimus var. exaltatus, S. integerrimus var. major, S. integerrimus var. ochroleucus
Web links