Species: Thalictrum occidentale var. occidentale Gray

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Thalictrum occidentale var. occidentale Gray

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TAXONOMY

Family:

Ranunculaceae

Genus:

Thalictrum

Species Synonyms:

none

Common Names:

western meadowrue

DISTRIBUTION

Canada:

southern Yukon – southwestern Mackenzie District, British Columbia – Alberta – southwestern Saskatchewan

Saskatchewan:

southwestern Saskatchewan; Cypress Hills – Coriander

Ecoregion:

Cypress Upland, Mixed Grassland

HABITAT

Saskatchewan:

in aspen or pine woods

RARITY STATUS

Provincial Status According
to Harms (2003):

Threatened

Nature Conservancy Status:

G5 S1S2

Saskatchewan Species at
Risk Status:

None

COSEWIC Status:

None

Thalictrum occidentale var. occidentale is threatened because of rarity in Saskatchewan. It is regionally restricted to the southwestern portion of the province. Some local populations are small and some larger. Possible threats have been identified for this species.

SPECIES DESCRIPTION

Height:

30 – 100 cm

Roots:

fibrous, thin, yellow to dark brown or black; rhizomes often present

Stems:

erect, glabrous

Leaves:

mostly cauline, blades 3 – 4-ternately compound

Leaflets:

10 – 30 mm wide, orbicular to obovate or cordate, tip 3-lobed, not distinctly veined, glabrous to glandular, lobed margins coarsely crenate

Inflorescence:

panicle, branches all about the same length, terminal, occasionally with some flowers in axils of leaves, open, many-flowered

Flowers:

unisexual; calyx 3.5 – 4.4 mm in staminate flowers, 1.5 – 2 mm in pistillate flowers, ovate, whitish, greenish or purplish tinged; corolla absent; stamens numerous, filaments 4 – 10 mm, purplish; stigmas often purplish

Fruits:

achene 6 – 9, spreading or reflexed, short-stalked, tapering at both ends, glandular, strongly 3-veined

THALICTRUM KEY FOR SPECIES FOUND IN SASKATCHEWAN

1 Achenes strongly flattened; flowers bisexual, perianth segments 5, stigmas included	T. sparsiflorum var. richardsonii
1 Achenes inflated; at least some flowers unisexual, perianth segments 4 or less, stigmas exserted	2

2 Leaflets entire (may be 3-lobed); leaf barely stalked, oblong, dark green above	T. dasycarpum
2 Leaflets with 5 to several crenate lobes; leaf stalked, nearly round, pale green above	3

3 Peduncles widely spreading, all about the same length; leaves thin, not distinctly veined	T. occidentale var. occidentale
3 Peduncles ascending, varying lengths; leaves thick, prominently veined	T. venulosum