Platanthera dilatata var. albiflora - White Bog-orchid

Phylum: Magnoliophyta - Class: Liliopsida - Order: Orchidales - Family: Orchidaceae

Above: White Bog Orchid in Rocky Mountain National Park

We first encountered this orchid on the drive down from the Alpine Ridge towards the west side of Rocky Mountain National Park. It was growing on the roadside at the bottom of a steep slope, in ideal position to take advantage of the moister conditions created by the run-off of rainwater from the higher ground above it.

Growing to a maximum height of around 50cm in ideal conditions, the pure white flowers are fragrant, echoing orchids of the same genus that occur in Europe, both in flower shape and fragrance, namely Platanthera chlorantha (Great Butterfly Orchid) and Platanthera bifolia (Lesser Butterfly Orchid).

Distribution

The range of this lovely wildflower is throughout the western mountains of North America, and White Bog Orchid grows in both Yellowstone National Park and in the Rocky Mountain National Park.

Habitat

The White Bog Orchid only grows in wet areas in meadows, along stream banks and in wet flushes; it occurs in lowlands and in subalpine areas throughout the west and central areas of the Rocky Mountains.

Etymology

The genus name Platanthera comes from Greek and means 'broad or wide anther', referring to the wide separation of the bases of the two pollinia in the Lesser Butterfly Orchid, which is the type species of the genus. (Not all Platanthera species display this charcter, however.) The specific epithet dilatata means 'expanded', while the subspecies name albiflora means 'with whote flowers'.

Flowering time

In the mountains this orchid blooms in August and September.