Burke: Cirsium scariosum vs. Cirsium undulatum

	Cirsium scariosum	Cirsium undulatum
	elk thistle, meadow thistle	wavy leaf thistle
Habit	Herbaceous perennial from a taproot, often acaulescent, or the stem up to 1 m. tall, thick and succulent, tapering slightly upward, somewhat spider-webby.	Stout, short-lived perennial from a tap-root, branched above and sometimes below the surface, 3-12 dm. tall, densely, closely, and persistently white-woolly throughout.
Leaves	Leaves numerous in a basal rosette in the acaulescent form, alternate in the cauline form; leaves spider-webby on the upper surface, slightly woolly below, weakly spiny, coarsely toothed to pinnatifid, broadly linear.	Leaves up to 3 dm. long, coarsely toothed to pinnatifid, the lobes ovate or deltoid, usually over 7mm. wide, the margins spiny.
Flowers	Heads densely clustered at the top of the stem, over-topped by the subtending leaves; involucre 2-3.5 cm. high, nearly glabrous, its bracts broad, well imbricate, the outer with short, erect spine tip, the inner less spiny and often with a scarious, fringed tip; flowers all tubular and perfect, the corollas whitish to pale pink or purplish, unequally cleft, the deepest sinuses 5-8 mm. deep, the tube about twice as long as the throat.	Heads several to numerous at the ends of the branches; involucre 2.5-4 cm. high, its bracts with a glandular-glutinous dorsal ridge, the inner with pointed tips, the others with spine tips 3-5 mm. long; flowers all ligulate, pink-purple, but often so pale as to appear dirty-white.
Fruits	Achene.	Achenes 4-7 mm. long, light brown.

	Cirsium scariosum	Cirsium undulatum
Flowering time	June-August	May-September
Habitat	Wet meadows, moist, sometimes alkaline ground, and forest openings from the foothills to fairly high elevations in the mountains.	Dry hillsides and plains at low elevations.
Distribution	Occurring east of the Cascades crest in Washington; British Columbia to California, east to the Rocky Mountains. [WildflowerSearch map] [BONAP county map]	Occurring east of the Cascades crest in Washington; British Columbia to California, east to Michigan and Texas. [WildflowerSearch map] [BONAP county map]
Origin	Native	Native
Conservation status	Not of concern	Not of concern
Sibling taxa	C. arvense, C. brevifolium, C. brevistylum, C. edule, C. flodmanii, C. hookerianum, C. inamoenum, C. remotifolium, C. undulatum, C. vulgare	C. arvense, C. brevifolium, C. brevistylum, C. edule, C. flodmanii, C. hookerianum, C. inamoenum, C. remotifolium, C. scariosum, C. vulgare
Web links	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria, Turner Photog. WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria, Turner Photog. WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Cirsium scariosum

Cirsium undulatum

elk thistle, meadow thistle

wavy leaf thistle

Habit

Herbaceous perennial from a taproot, often acaulescent, or the stem up to 1 m. tall, thick and succulent, tapering slightly upward, somewhat spider-webby.

Stout, short-lived perennial from a tap-root, branched above and sometimes below the surface, 3-12 dm. tall, densely, closely, and persistently white-woolly throughout.

Leaves

Leaves numerous in a basal rosette in the acaulescent form, alternate in the cauline form;

leaves spider-webby on the upper surface, slightly woolly below, weakly spiny, coarsely toothed to pinnatifid, broadly linear.

Leaves up to 3 dm. long, coarsely toothed to pinnatifid, the lobes ovate or deltoid, usually over 7mm. wide, the margins spiny.

Flowers

Heads densely clustered at the top of the stem, over-topped by the subtending leaves;

involucre 2-3.5 cm. high, nearly glabrous, its bracts broad, well imbricate, the outer with short, erect spine tip, the inner less spiny and often with a scarious, fringed tip;

flowers all tubular and perfect, the corollas whitish to pale pink or purplish, unequally cleft, the deepest sinuses 5-8 mm. deep, the tube about twice as long as the throat.

Heads several to numerous at the ends of the branches;

involucre 2.5-4 cm. high, its bracts with a glandular-glutinous dorsal ridge, the inner with pointed tips, the others with spine tips 3-5 mm. long;

flowers all ligulate, pink-purple, but often so pale as to appear dirty-white.

Fruits

Achene.

Achenes 4-7 mm. long, light brown.