Mycoheterotrophic Plants

How many of them are there?

Families and genera statistics

Four species of  MHP occur in Bryophytes. Two species in the genus Aneura (Aneuraceae) and two species in Buxbaumia (Buxbaumiaceae).

One species of gymnosperms, Parasitaxus usta (Podocarpaceae) is mycoheterotrophic and parasitic at once.

Burmanniaceae comprise 8 genera and 67 species of MHP. Apteria, Dictyostega, Marthella and Miersiella contain 1 species each, Dictyostega orobanchoides has 3 subspecies. Campylosiphon and Hexapterella include 2 species, Burmannia 23 achlorophyllous species (plus some more species with various reductions of photosynthetic ability) and Gymnosiphon 36 species.

Thismiaceae include 5 genera and 126 species. By far the largest genus is Thismia with 103 species and 1 variety. Hence, in competition with the orchid genus Gastrodia (97 species), it is the largest mycoheterotrophic genus in the plant kingdom. Afrothismia has 15 species and 1 variety, Oxygyne 6 species. Haplothismia and Tiputinia have 1 species each. Some authors keep Afrothismia gabonensis as a valid taxon (counting 16 species), which, however, hast been attributed as synonym to A. saingei by Maas-van de Kamer and Maas (2010). Likewise, Thismia versteegii became synonymized with T. crocea by Jonker (1938), which has been challenged by Larsen (1965). Unfortunately, the type material of T. versteegii got lost.

Triuridaceae have 8 genera and 66 species. The largest genus is Sciaphila with 50 species and one variety, Triuris encompass 4 species, Kihansia, Kupea, Lacandonia, Peltophyllum and Triuridopsis contain 2 species each, Soridium is monotypic. Seychellaria spp., for years kept in an own genus, became included in Sciaphila by Christenhusz et al. (2018).

Corsiaceae include 3 genera and 28 species. Arachnitis has 2 species, Coriopsis 1 species and Corsia 25 species and 1 variety.

Iridaceae includes 1 MHP genus (Geosiris) with 3 species.

Orchidaceae encompass 44 genera with mycoheterotrophic representatives, 326 orchid species are fully mycoheterotrophic. The genus with the most MHP is Gastrodia with 97 species, next in size is Lecanorchis with 23 species and 7 varieties. Didymoplexis inlcudes 22 species and 4 varieties, Aphyllorchis 20 species and 1 variety, Neottia has 16 species, Eulophia 13 species, Dipodium 12 species, Corallorhiza 11 species including 7 varieties and 1 form, Bletia 10 species. Didymoplexiella (together with Didymoplexiopsis challenged in its genus rank by Suetsugu & Hsu (2019)) comprises 8 species, Pseudovanilla and Cyrtosia contain 7 species each, Cephalanthera encompass 6 species. Epipogium, Rhizanthella, and Yoania have 5 species each, 4 species of MHP are included in each case of Odontochilus, Silvorchis, Uleiorchis, Galeola and Auxopus, 3 of them belong to any of the genera Cystorchis, Danhatchia, Limodorum, Chamaegastrodia and Tropidia. Brachycorythis, Corybas, Crepidium, Erythrorchis, Pogoniopsis and Wullschlaegelia all encompass 2 MHP species, and, finally, the following genera only have 1 achlorophyllous representative: Cymbidium, Degranvillea, Didymoplexiopsis (challenged as a genus by Suetsugu & Hsu 2019), Platanthera, Risleya, Stereosandra, Arthrochilus, Aspidogyne, Burnettia, Cremastra, Cryptostylis and Thaia.

Petrosaviaceae, an isolated family in its own order, with only 2 species in the genus Petrosavia.

Ericaceae have 17 species of MHP in 13 genera, most of which are monotypic. Cheilotheca has 3 species, Monotropsis and Monotropastrum contain 2 species, Monotropastrum humile with one additional variety. Hypopitys has 2 subspecies. Pyrola contains 42 species, but only a variant of Pyrola picta is mycoheterotrophic.

In Polygalaceae only the genus Epirixanthes, comprising 7 species and 2 forms, is entirely devoid of chlorphyll. Other species in Polygala and Salomonia show reductions in photosynthetic surface, e.g. Polygala setacea (Long and Lakela 1971) or Salomonia ciliata (van der Meijden 1988), However, they are, according to our criterium, not included here.

Gentianaceae include 4 genera with 27 mycoheterotropohic species. Voyria is the largest genus with 21 species and 3 varieties, Exacum encompasses 4 species, whereas Exochaenium and Voyriella have 1 species each.

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