Obolaria and Bartonia

Additionally to the species listed here, two more genera of the Gentianaceae are also considered to be partially mycoheterotrophic. Obolaria virginica is the only species in its genus, having scale like leaves at the lower stem which become bigger to spathulate-obdeltoid leaves towards the inflorescence. The fleshy stem and the leaves are purplish-green. The roots, however, are coralloid like many of the Voyria species and mycorrhizal (Gilg, 1895, Holm 1897, Gillett 1959, Wood and Weaver 1982).
Bartonia comprises four species, B. virginica, B. verna, B. paniculata, the latter of which has two subspecies (Gillett 1959), and B texana (Correll 1966). All species have only scale leaves but an overall green appearance. In contrast to Obolaria virginica the Bartonia species are more delicate plants. However, also Bartonia has a fleshy, sparsely branched and mycorrhizal root system (Holm 1906).