Burke: Cirsium altissimum vs. Cirsium scariosum

	Cirsium altissimum	Cirsium scariosum
		elk thistle, meadow 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.
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.
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.
Fruits		Achene.

	Cirsium altissimum	Cirsium scariosum
Flowering time		June-August
Habitat		Wet meadows, moist, sometimes alkaline ground, and forest openings from the foothills to fairly high elevations in the mountains.
Distribution	[WildflowerSearch map] [BONAP county map]	Occurring east of the Cascades crest in Washington; British Columbia to California, east to the Rocky Mountains. [WildflowerSearch map] [BONAP county map]
Origin		Native
Conservation status		Not of concern
Sibling taxa	C. arvense, C. brevifolium, C. brevistylum, C. edule, C. flodmanii, C. hookerianum, C. inamoenum, C. remotifolium, C. scariosum, C. undulatum, C. vulgare	C. arvense, C. brevifolium, C. brevistylum, C. edule, C. flodmanii, C. hookerianum, C. inamoenum, C. remotifolium, C. undulatum, C. vulgare
Web links	Local Web sites: Flora NW, PNW Herbaria 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 altissimum

Cirsium scariosum

elk thistle, meadow 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.

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.

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.

Fruits

Achene.