Ruth and I cowrote today’s entry:
First of all, we would like to thank Kevin Deboer for today’s photographs, posted in the Cephalanthera austiniae photo gallery on the E-Flora BC site (and used here with permission).
Who would have thought that the dainty and glamorous Orchidaceae would supply two of Halloween week’s specimens? This ghostly species, Cephalanthera austiniae, is commonly known as the phantom orchid. The common name is due to its white colouration and preferred habitat — mature and old-growth forests, where it resides in understories with few competitors.
Due to the lack of any colouration, it is readily apparent that this species does not photosynthesize. Instead, it is a mycoheterotroph; “an achlorophyllous, nonphotosynthetic plant that obtains fixed carbon from photosynthetic plants via mycorrhizal fungi” (ref.). This mechanism is similar to the one employed by Monotropa uniflora. In the case of Cephalanthera austiniae, it grows in association with fungal species in the Thelophoraceae. As noted by Brian Klinkenberg in this article on the phantom orchid in British Columbia, it is actually a subset of the Thelophoraceae — a group known as the black thelophorids — in which it shares an association. Black thelophorids are restricted to mature forests, hence one of the restrictions on phantom orchid distribution and abundance.
Cephalanthera austiniae is a native to British Columbia and extends south to Washington, Oregon, California and Idaho. In British Columbia, the phantom orchid is restricted to thirteen sites in three general locales: the Saanich Peninsula on Vancouver Island, Salt Spring Island and near Chilliwack. This restricted range and low number of plants (only 42 flowering stems observed within BC in 2000) has led to it being designated a red-listed species in British Columbia. BOO!