Venus' Looking Glass: Triodanis biflora and Triodanis perfoliata

Two Triodanis species - Triodanis biflora and Triodanis perfoliata – grow in this area. For quite a while I didn’t realize I was looking at two different species but I finally figured it out. The flowers looked identical. These species are differentiated by their vegetative growth. T. biflora is commonly called Small Venus' Looking-glass; T. perfoliata is called the Clasping Venus' Looking-glass. T. biflora has a slender stalk with non-perfoliate leaves (leaves not through the leaves) and few flowers. T. perfoliata growth is much heavier in appearance with perfoliate leaves and many flowers. In this area, T. biflora begins blooming a little earlier than T. perfoliata but the blooming seasons overlap.

The flowers

A developing bloom.

In full bloom.

Triodanis biflora

The slender stem with non-perfoliate leaves. (These flower stems are usually upright)

A close up of a bloom on a non-perfoliate stem

Triodanis perfoliata

A sturdier stem with multiple flowers

The perfoliate leaf

Blooms in various stages of development

Triodanis perfoliata is native to the United States and Canada. This species grows in all of the lower states in the United States except Nevada; it also grows in British Columbia, Ontario, and Quebec.

Tridanis biflora is also native to the United States but only grows in the lower U. S. from Oregon and California through Arizona and New Mexico. It also grows in states south of and including Nebraska, Missouri, Illinois, Kentucky and Virginia as well as in New York State and Pennsylvania.
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Distribution Map:
United States Department of Agriculture Plants Database:
- Triodanis biflora (Small Venus' Looking-glass)
- Triodanis perfoliata (Clasping Venus' Looking-glass)
University of North Carolina Herbarium:
- Triodanis perfoliata
- Triodanis biflora

Identification resources:
Southeastern Flora:
- Venus' Looking-glass (Triodanis biflora)
- Venus' Looking-glass (Triodanis perfoliata)
Natural and Naturalized Plants of the Carolinas and Georgia: Triodanis perfoliata
Missouri Plants:
- Specularia biflora
- Specularia perfoliata

Related posts:
- 2010: Year Of The Wildflower