Autotrophy, though common among plants, isn’t the only way plants make a living. Some plants have lost all photosynthetic abilities and instead rely on symbiotic relationships with fungi. Even some leafy green plants that appear fully autotrophic meet a portion of their energy demands via partnerships with fungi.
These plant adaptations fall into the category of mycoheterotrophy. Here, Hynson et al. synthesise the largest data set available on the ecophysiologies of mycoheterotrophs in the families Ericaceae and Orchidaceae. They find that enrichment patterns of carbon and nitrogen stable isotope composition, together with nitrogen concentrations reveal plant trophic status and familial identity.
Nicole A. Hynson, Julienne M.-I. Schiebold, Gerhard Gebauer, 2016, 'Plant family identity distinguishes patterns of carbon and nitrogen stable isotope abundance and nitrogen concentration in mycoheterotrophic plants associated with ectomycorrhizal fungi', Annals of Botany, vol. 118, no. 3, pp. 467-479 http://dx.doi.org/10.1093/aob/mcw119