OregonFlora: Eriophorum chamissonis vs. Eriophorum

	Eriophorum chamissonis	Eriophorum
	russet cottongrass	cottongrass
Habit		Herbs perennial, rhizomatous.
Culms	somewhat trigonous; (20)30–70(80) cm; stout; to 1.5(4) mm thick basally.	solitary or clustered, trigonous or terete.
Leaves	blades filiform, trigonous-channeled; (2)3–10 cm × 1–2 mm; distal 1–2 leaf sheaths bladeless.	basal and cauline; cauline leaves sometimes consisting of bladeless sheaths; ligules present; blades to 25 cm × 2.5–4 mm.
Inflorescences	involucral bracts absent.	terminal; spikes 1–10(30); involucral bracts 1–several; scale-like or blade-bearing and leaf-like throughout.
Spikes	1; floral scales blackish to purplish brown; proximal 1–7 scales empty, obovate or trigonous-obovate, 4–20 mm; margins white or paler; as wide as dark portion; apex blunt; distal scales obovate to ovate-lanceolate; margins hyaline, 1 mm wide or wider.	floral scales (10)20–200, spirally arranged; each subtending a flower or the proximal few empty.
Flowers	perianth bristles 20–40 mm, red-brown to white; anthers (0.6)1.5–3 mm.	bisexual; perianth persistent; of (8)10–25 hair-like; smooth bristles, greatly elongate, essentially straight, usually obscuring most of scales in spike; much longer than achene; stamens 1–3; styles deciduous; stigmas 3.
Achenes	oblong-obovoid, 2–2.7 mm; as wide as long.	trigonous.
2n	=58.

	Eriophorum chamissonis	Eriophorum
Distribution	[WildflowerSearch map] [BONAP county map]	[BONAP county map]
Discussion	Coastal bogs and marshes. 0–50 m. Est. ID, WA; north to AK, east to WI, southeast to CO; Eurasia. Native. Eriophorum chamissonis is a lovely plant with large, shiny, dense heads of long, red-brown or bronze hairs.	Mostly in cool temperate, alpine, and arctic regions of the northern hemisphere. Approximately 25 species; 3 species treated in Flora.
Source	Flora of Oregon, volume 1, page 244 Barbara Wilson, Richard Brainerd, Nick Otting	Flora of Oregon, volume 1, page 244 Barbara Wilson, Richard Brainerd, Nick Otting
Sibling taxa	E. angustifolium, E. gracile
Subordinate taxa		E. angustifolium, E. chamissonis, E. gracile
Web links	Local floras: BC, OR, WA Local Web sites: 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: 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

Eriophorum chamissonis

Eriophorum

russet cottongrass

cottongrass

Habit

Herbs perennial, rhizomatous.

Culms

somewhat trigonous; (20)30–70(80) cm; stout; to 1.5(4) mm thick basally.

solitary or clustered, trigonous or terete.

Leaves

blades filiform, trigonous-channeled; (2)3–10 cm × 1–2 mm;

distal 1–2 leaf sheaths bladeless.

basal and cauline;

cauline leaves sometimes consisting of bladeless sheaths;

ligules present;

blades to 25 cm × 2.5–4 mm.

Inflorescences

involucral bracts absent.

terminal;

spikes 1–10(30);

involucral bracts 1–several; scale-like or blade-bearing and leaf-like throughout.

Spikes

1; floral scales blackish to purplish brown;

proximal 1–7 scales empty, obovate or trigonous-obovate, 4–20 mm;

margins white or paler; as wide as dark portion;

apex blunt;

distal scales obovate to ovate-lanceolate;

margins hyaline, 1 mm wide or wider.

floral scales (10)20–200, spirally arranged; each subtending a flower or the proximal few empty.

Flowers

perianth bristles 20–40 mm, red-brown to white;

anthers (0.6)1.5–3 mm.

bisexual;

perianth persistent; of (8)10–25 hair-like; smooth bristles, greatly elongate, essentially straight, usually obscuring most of scales in spike; much longer than achene;

stamens 1–3;

styles deciduous;

stigmas 3.

Achenes

oblong-obovoid, 2–2.7 mm; as wide as long.

trigonous.

=58.