Species: Tradescantia occidentalis (Britt.) Smyth

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Tradescantia occidentalis (Britt.) Smyth

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TAXONOMY

Family:

Commelinaceae

Genus:

Tradescantia

Species Synonyms:

none

Common Names:

western spiderwort
prairie spiderwort
spiderwort

DISTRIBUTION

Canada:

southeastern Alberta, south-central Saskatchewan, southwestern Manitoba

Saskatchewan:

south-central Saskatchewan; Elbow Sand Hills

Ecoregion:

Moist Mixed Grassland

HABITAT

Saskatchewan:

southwest-facing slopes on semi-active to stabilized sand dunes and sandy prairies

Associated Species:

hairy prairie clover, Indian ricegrass, needle and thread grass, purple prairie clover, sand dune wheatgrass, Schweinitz’s sedge

RARITY STATUS

Provincial Status According
to Harms (2003):

Endangered

Nature Conservancy Status:

G5 S1

Saskatchewan Species at
Risk Status:

Endangered

COSEWIC Status:

Threatened

Western spiderwort is endangered because it is regionally restricted and the Saskatchewan population is isolated from the populations in Manitoba, Alberta, and the United States. Also, this plant thrives in a delicate sand dune environment and may be affected by cattle grazing and other human uses of the land. This species is usually locally numerous within each population, but threats like leafy spurge invasion may cause population decline in the future.

SPECIES DESCRIPTION

Height:

30 – 70 cm

Roots:

fibrous roots fleshy

Stems:

herbaceous perennial, erect, branched, persistent leaf bases papery, bluish-green, hairless, mucilaginous; nodes 2 – 6, swollen, internodes to 25 cm long;

Leaves:

alternate, sheathing, sheath inflated to 2 – 4 times width of blade, blade 9 – 33 cm long, 4 – 12 mm wide, often folded, grass-like, linear, venation parallel, somewhat bluish-tinged, hairless, mucilaginous, margin smooth

Inflorescence:

terminal flowers mature first, inflorescence terminal at ends of main branches and stems, few to many-flowered, 1 – 2 flowers open at a time per inflorescence; bracts 2, leaf-like, 6 – 20 cm long, hairless; flower stalks to 20 mm, glandular

Flowers:

sepals 3, 8 – 13 mm, 2 – 3 mm wide, elliptic to lance-shaped, green, glandular-hairy; petals 3, 8 – 15 mm long, ovate, dark purple to light purple to pink, exude colour when touched; stamens 6, filaments purple or pink, hairy, anthers bright yellow; ovary superior, 3-carpellate; stigma and style purple, glandular to hairless

Fruits:

capsule 3-valved; seeds 2 – 6, 2 – 4 mm long, compressed oblong

*HOW TO IDENTIFY TRADESCANTIA* IN SASKATCHEWAN**

Western spiderwort is the only member of the Commelinaceae native to Saskatchewan. Although this plant may look grass-like in its vegetative state, it can easily be identified by the purple flowers, mucilage, and inflated leaf sheaths.