Western spiderwort (Tradescantia occidentalis) COSEWIC assessment and status report: chapter 3

Species Information

Name and classification

Scientific name:

Tradescantia occidentalis (Britt.) Smyth

Common Name:

Western Spiderwort

Family:

Commelinaceae; spiderwort family

Major Plant Group:

Monocot flowering plant

Description

Western spiderwort (Tradescantia occidentalis (Britt.) Smyth) is an erect perennial with slender stems, 5-61 cm in height (Figure 1). The leaves are linear, with conspicuously ribbed, curved sheaths, swollen at the juncture with the node. The roots are stout and fleshy with slender fibrous roots. The flowers are in terminal few- to many-flowered cymes which are subtended by elongated bracts that are similar in appearance to the foliage leaves. Petals are 10-15 mm long, rose to dark blue in colour, arranged in threes, slightly pointed at the tips. There are six stamens, hairy, with bright yellow anthers. The fruiting structure is a dry papery capsule, 0.4-1.0 cm in length, containing 2-6 seeds. Tradescantia is the only genus in the family Commelinaceae that is native to Canada. There is only one other native Canadian species of Tradescantia, namely, Tradescantia ohiensis Raf., a species restricted to southwestern Ontario in distribution. Tradescantia virginiana L. is known from Ontario only as a garden escape.

Figure 1. Illustration of western spiderwort (courtesy of Manitoba Conservation, Wildlife and Ecosystem Protection
Branch).

Figure 1. Illustration of western spiderwort (courtesy of Manitoba Conservation, Wildlife and Ecosystem Protection Branch).

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