Mycoheterotrophs: A Wander in the Woods

Botanists studying mycoheterotrophic plants were recently excited by the discovery of one missing for some 150 years. Thismia neptunis was first found in 1866 in the wilds of Sarawak. Now Czech researchers have announced its rediscovery in the journal Phytotaxa. If you like to wallow in the weird, you'll rejoice in mycoheterotrophs. Better yet, you don't have to risk visiting remote rainforests to discover examples. A wander through local woods could prove rewarding.

If you want to prove informed you can call them MHPs but by what ever designation, mycoheterotrophs are a strange bunch. Unlike the majority of higher plants, they lack chlorophyll and so cannot photosynthesize. They depend on their nutrition for a symbiotic relationship with mycorrhizal fungi. This explains their botanical assignation. As usual, the Greeks had words for it: mykes (fungus) + heteros (another) + trophe (nutrition) This mode of life means MHPs spend almost all their life below ground, safe from herbivores and botanists. They only emerge with the urge to procreate, pushing forth their blooms above ground. These are often strange and unusual in appearance. The one thing they have in common: the lack of leaves. One of the most widely occurring is Monotropa uniflora, variously known as Indian Pipe, Ghost Plant or, grimly, Corpse Plant. Not only is it to be found across Canada and much of the US, but also in temperate European Russia, Asia and even northern South America. The strange white flowers, just four to 10 inches tall, do rather resemble old-fashioned clay pipes and are pollinated by small bumblebees. They may be found in damp shady woods, often of beech. We've found them in such habitats south of Ontario's Algonquin Park after heavy rain. Reportedly the shoots are edible, tasting like asparagus but probably toxic. Closely related is the slightly taller Pinesap, Monotropa hypopithys, pushing through the leaf mould under pines or firs in temperate regions of the Northern Hemisphere. According to the US Forest Service it is widely distributed throughout US and Canada. Pine woods of West Virginia, Maryland southwards may harbour Sweet Pinesap or Pygmy-Pipes, often hidden by fallen foliage. Appropriately formally named Monotropsis odorata it emits the fragrant odour of violets. Yet another mycoheterotrophic denizen of northeastern North American pine woods is the odd Pterospora andromedea, the Giant Bird's-Nest or Pinedrops, local but widespread in Canada.

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All these species tend to support pale blooms although these do appear prominent in the dim light of forest floor. Different are the spectacular red blooms of the Snow Plant, Sarcodes sanguinea, from montane areas of northwestern North America. While you are walking the woods why not also look out for mycoheterotrophic orchids. Orchids, you say, in North America? Yes, Canada has about 60 or so species, and the United States around 200 (although almost a 100 of these are from Florida). Like so many of these main stream orchids though, those species of MHPs throw up small spikes of blooms. There are about a dozen species of Corallorhiza, all but one restricted to North America. That is the Northern Coralroot, Corallorhiza trifida, found from Newfoundland to California but also across Eurasia According to database Mycoheterotrophic Plants: How many of them are there? 48 non-orchid genera contain MHP species, and 280 non-orchid species are mycoheterotrophic. This leaves out an unknown number of the Orchidaceae. Thismia neptunis is one of a genus known from Hong Kong through Thailand and Southeast Asia through to Australia and New Zealand. Surprisingly, another Thismia was described in 1910 from the United States. T. americana, known as the Banded Trinity, was found in the wetlands surrounding Chicago's Lake Calumet. It remains a mystery how it was completely isolated from rest of genus. But don't go searching for it. Its habitat was 'developed' as an industrial site. Today T. americana is believed extinct. Sic transit gloria mundi.