Mycoheterotrophic Plants

How many of them are there?


Mycoheterotrophic plant species (MHP, Leake 1994) lack chlorophyll and depend on their mycorrhizal fungus for carbon and nutrient supply. MHP were first counted by Johow (1889), who estimated 160 species of “achlorophyllous humus plants” in 43 genera and 5 families. Schmucker (1959) already counted 352 “holosaprophytic” species in 48 genera and 6 families. Furman and Trappe (1971) referred to “roughly 400 species”, 50 genera and 7 families. In an review on MHPs Leake (1994) lists 417 MHP species in 87 genera and 11 families. My own preliminary reassessment of Leake's list in 2008 resulted in 438 species/84 genera/10 families, but was just a rough estimate. The most recent assessment is of Merckx (2013) in his introducing chapter to the first book exclusively dedicated to MHP: Mycoheterotrophy - The Biology of Plants living on Fungi. On page 9 he says: "At least 514 species of angiosperms and a single liverwort species entirely depend on fungal carbon during their complete life cycle". This website aims to set up a list of all mycoheterotrophic plants on earth, combined with additional informations such as synonymy, taxonomic history and a bibliography. So far, the list of accepted species with taxonomic comments as well as synonyms (listed above the accepted taxa, both in alphabetic order) are complete except for Orchidaceae. The bibliography (1391 references) collects the bibliographic data of the taxonomic literature mentioned up to now, as well as other articles dealing with all aspects of mycoheterotrophic plants. The citations in the taxonomic comments (pages) are hyperlinked with the bibliographic data. You find the taxonomic comments under the flag 'Descriptions' when choosing a species name in the taxonomy 'Mycoheterotrophic Plants'.
To the date of 14th of December 2018 this list enumerates 2 families/2 genera/4 species of Bryophytes, 1 Gymnosperm, 6 families/28 genera/254 species of non-orchid monocots, and 3 families/17 genera/47 species of eudicots. This sums up to 12 families/48 genera/306 species of non-orchid mycoheterotrophic plants. Dictyostega orobanchoides, Hypopitys monotropa, Voyria aurantiaca, and V. corymbosa are subdivided in subspecies, Afrothismia winkleri, Monotropastrum humile, and Thismia hexagona have one variety each, and Epirixanthes papuana as well as E. elongatata have a form alba, respectively. I added more specific statistics in the 'Desriptions' of each family.
Aditionally, 21 genera and 106 species of mycoheterotrophic orchids are listed, however, this is far from being complete.

The criterium to be included in this list is "optical achlorophylly" or at least nearly such. We are aware of intergrading dependences on the mycorrhizal fungus even in green plants (see the pages The case of "Pyrola aphylla", Obolaria and Bartonia or Stemona aphylla), as well as of different amounts of chlorophyll content, which often is even hidden by other colouring compounds.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith