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Is plant parasitism on fungi. It is best known from orchids, as all of the approximately 28000 orchid species are mycoheterotrophs for at least part of their lives - so-called initial mycoheterotrophs. However, about 200 species are parasites on fungi for their entire lives. Mycoheterotrophy is most common in the tropics, where it is also found in many other families that together number about 400 species all over the world.
Mycoheterotrophy evolved more than 40 times and it appeared in monocots, dicots, ferns or lycopodiophyta.....
An example
An example
of the orchid Anacamptis morio, which is initially mycoheterotrophic but probably autotrophic as an adult. Recent studies do not completely exclude the possibility that there is some carbon gain from fungi in adulthood, but this species, as well as the majority of all orchids, is thought to be fully atotrophic in adulthood.
Not an orchid
Not an orchid
but a gentian! This is Voyria from the Amazon rainforest, which is completely mycoheterotrophic throughout its life. It lives underground as a nest of thick roots, only coming to the surface when it needs sex - to flower. It is a difficult plant to find.
Not mycoheterotrophic but close to be
Not mycoheterotrophic but close to be
as these species have some chlorophyll. Not much, so it basically acts like a normal mycoheterotroph, but is still capable of a little photosynthesis, as you can see on this picture. Most of the time this species is more brown and was thought to be completely mycoheterotrophic.
Mixotrophs are green
Mixotrophs are green
like this Moneses uniflora (Ericaceae). This pyroloid (as it belongs to the subfamily Pyroloideae) is almost completely autotrophic as an adult.
Mycoheterotrophs share! well at least traits...
Mycoheterotrophs share! well at least traits...
Mycoheterotrophic plants that evolved independently, even on opposite sides of the phylogenetic tree, such as orchids and pyroloids, share similar traits such as dust-seeds or embryo reduction. Both groups even share protocorm formation, unipolar development and even the use of trehalose. Trehalose is a fugal sugar and normal plants (unlike orchids and protocorms) cannot use it as a carbon source.
Rarely mixotropic albinos occurs
Rarely mixotropic albinos occurs
and this is a completely wrong title, because most of them are no longer mixotrophs but mycoheterotrophs. If they are completely white, as in the picture, they no longer have their own photosynthesis. Such albino variants are mostly found in mixotrophic species because they already know how to steal fungal carbon. In other plants, mutations leading to albinism are usually lethal.
Mixotrophs are step towards MH
Mixotrophs are step towards MH
Mycoheterotrophy evolved probably through intermediate step - mixotrophy. It is unlikely that albinism would be intermediate step towards evolution of mycoheterotrophy. Slower step by step evolution via reduction of leaves and slow loss of photosynthetic pigments seem sto be more likely.
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