Species: Achillea millefolium var. megacephala (Raup) Boivin

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Achillea millefolium var. megacephala (Raup) Boivin

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TAXONOMY

Family:

Asteraceae or Compositae

Genus:

Achillea

Species Synonyms:

none

Common Names:

large-headed woolly yarrow
largehead yarrow

DISTRIBUTION

Canada:

Lake Athabasca

Saskatchewan:

Lake Athabasca, south shore

Ecoregion:

Athabasca Plain

HABITAT

Saskatchewan:

sand dunes and lakeshores

Associated Species:

Picea glauca

RARITY STATUS

Provincial Status According
to Harms (2003):

Threatened

Nature Conservancy Status:

G5T1 N5T1 S1

Saskatchewan Species at
Risk Status:

Vulnerable

COSEWIC Status:

Special Concern

Achillea millefolium var. megacephala is threatened because it is endemic to northern Saskatchewan. In addition, most local populations are small. This species occurs at least in part in the Athabasca Sand Dunes Provincial Wilderness Park and is protected under Provincial Park legislation; however, the sand dune habitat in which it grows is very fragile.

SPECIES DESCRIPTION

Height:

30 – 80 cm tall

Roots:

rhizomes woody, reddish-brown

Stems:

caespitose; green or reddish, densely lanate when mature, less hairy when young

Leaves:

alternate, simple, reduced in size upwards, to 0.8 cm wide, lanceolate, pinnate-pinnatifed, fern-like in appearance, lobes of leaf ovate, crowded, densely white or yellowish-tomentose

Inflorescences:

heads several in round-topped corymb, < 10 cm broad; peduncle densely tomentose; phyllaries in 3 – 4 rows, dry, densely tomentose, outer rows smaller, inner row longer with conspicuous midvein, cream-coloured with brown margins; receptacle chaffy

Flowers:

ligulate and tubular flowers; ligulate flowers 5 – 12, pistillate, fertile, ligule 4 – 6 mm long, white; tubular flowers 10 – 75, perfect, fertile, yellow

Fruits:

achene oblong, flattened, glabrous; pappus absent

ACHILLEA MILLEFOLIUM KEY FOR VARIETIES FOUND IN SASKATCHEWAN

1 Phyllaries with straw coloured margins	var. occidentalis
1 Phyllaries with dark brown to black margins	2

2 Stems and leaves densely lanate (hairs covering stem surface); lobes of leaves ovate, crowded; lower leaves to 0.8 cm wide; heads to 5 mm wide, 4 – 6 mm long; flowers large in proportion to leaves (for Achillea)	var. megacephala
2 Stems and leaves more or less lanate; lobes of leaves narrow and thin, not crowded; lower leaves to 2.5 cm wide; heads to 3 mm wide, 2 – 5 mm long; flowers small in proportion to leaves	var. borealis