Monday, November 8, 2010

Northern Twayblade (Listera borealis)

All the Listeras are small with small flowers, but if it is possible to have a favorite among them, this would be mine.  Perhaps that is only because it brings back memories of several fabulous backpacking trips in Mount Robson Provincial Park in British Columbia, but it is nonetheless the species in this genus that stands out in my mind.

The plant is only 10-20 cm tall and the 5-15 flowers, fewer in number than Listera banksiana, are only about a cm long.  The plant has two and occasionally three leaves opposite each other about midway up the stem and flowers early in the summer, though we have found it well into August at higher elevations, usuall as single plants and often growing with Listera cordata.

The plant is found from Alaska all across Canada and in the northwestern United States as far south as Utah and Colorado.  It is reported to be rare and local, but we have found it in fairly large numbers in the Mount Robson area, usually growing in damp shaded areas at the edge of woodlands.  We have not, however, found it in Washington.

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