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

Large-headed woolly yarrow 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:

tufted, green or reddish, densely lanate when mature, less hairy when young

Leaves:

alternate, simple, reduced in size upwards, to 0.8 cm wide, lance-shaped, shallowly to deeply pinnate, fern-like in appearance, lobes of leaf oval, crowded, densely white or yellowish woolly-hairy

Inflorescences:

heads several in round-topped inflorescence, lower flower stalks longer than the upper, < 10 cm broad; inflorescence stalk densely woolly-hairy; bracts in 3 – 4 rows, dry, densely woolly-hairy, outer rows smaller, inner row longer with conspicuous midvein, cream-coloured with brown edges; receptacle with dry scales or bracts

Flowers:

ray and disc flowers; ray flowers 5 – 12, pistillate, fertile, petals 4 – 6 mm long, white; disc flowers 10 – 75, perfect, fertile, yellow

Fruits:

achene oblong, flattened, hairless; pappus absent

ACHILLEA MILLEFOLIUM KEY FOR VARIETIES FOUND IN SASKATCHEWAN

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

2 Stems and leaves densely woolly (hairs covering stem surface); lobes of leaves oval, 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 woolly; 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