OregonFlora: Cirsium altissimum vs. Cirsium

	Cirsium altissimum	Cirsium
		thistle
Habit		Herbs perennial or biennial; taprooted or from creeping roots.
Stems		erect, branched or simple, sometimes spiny-winged.
Leaves		basal and cauline, alternate; margins entire to deeply toothed or pinnately lobed; lobes and teeth usually spiny.
Inflorescences		heads solitary at branch tips or distal axils, or in raceme- or panicle-like arrays.
Receptacles		flat to convex; very bristly; paleae 0.
Florets		corollas bilateral, white or cream-colored to pink, red, or purple; style tips elongate.
Phyllaries		many in 5–20 series, imbricate or not; margins usually entire or occasionally scarious, ciliate-spiny, or erose; midveins sometimes with glutinous ridges.
Fruits		compressed; ovoid, tan to dark brown, glabrous, attachment scar off-center; pappi in 3–5 series, persistent or deciduous in rings.
Heads		discoid, pedunculate or sessile.

	Cirsium altissimum	Cirsium
Distribution	[WildflowerSearch map] [BONAP county map]	[BONAP county map]
Discussion		Africa, Asia, Europe, North America. ~200 species; 15 species treated in Flora. The taxonomy of Cirsium is complicated by hybridization and a high level of morphological variation within species. Style tips are measured including the somewhat swollen nodes and fused portions of style branches. Cirsium ochrocentrum var. ochrocentrum has been collected once in Oregon (2013) but does not appear to be naturalized.
Source		Flora of Oregon, volume 2, page 224 Bridget Chipman
Sibling taxa	C. andersonii, C. arvense, C. brevifolium, C. brevistylum, C. ciliolatum, C. cymosum, C. douglasii, C. eatonii, C. edule, C. edule x Cirsium remotifolium, C. inamoenum, C. occidentale, C. ochrocentrum, C. remotifolium, C. scariosum, C. undulatum, C. vulgare
Subordinate taxa		C. andersonii, C. arvense, C. brevifolium, C. brevistylum, C. ciliolatum, C. cymosum, C. douglasii, C. eatonii, C. edule, C. inamoenum, C. occidentale, C. ochrocentrum, C. remotifolium, C. scariosum, 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: 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

thistle

Habit

Herbs perennial or biennial; taprooted or from creeping roots.

Stems

erect, branched or simple, sometimes spiny-winged.

Leaves

basal and cauline, alternate;

margins entire to deeply toothed or pinnately lobed;

lobes and teeth usually spiny.

Inflorescences

heads solitary at branch tips or distal axils, or in raceme- or panicle-like arrays.

Receptacles

flat to convex; very bristly;

paleae 0.

Florets

corollas bilateral, white or cream-colored to pink, red, or purple;

style tips elongate.

Phyllaries

many in 5–20 series, imbricate or not;

margins usually entire or occasionally scarious, ciliate-spiny, or erose;

midveins sometimes with glutinous ridges.

Fruits

compressed; ovoid, tan to dark brown, glabrous, attachment scar off-center;

pappi in 3–5 series, persistent or deciduous in rings.

Heads

discoid, pedunculate or sessile.

Cirsium altissimum

Cirsium

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Africa, Asia, Europe, North America. ~200 species; 15 species treated in Flora.

The taxonomy of Cirsium is complicated by hybridization and a high level of morphological variation within species. Style tips are measured including the somewhat swollen nodes and fused portions of style branches. Cirsium ochrocentrum var. ochrocentrum has been collected once in Oregon (2013) but does not appear to be naturalized.

Source

Flora of Oregon, volume 2, page 224
Bridget Chipman

Sibling taxa