Roots of Voyria truncata retain the primary root structure, even though they can grow as thick as 2 mm in diameter. These root diameters are due to a retained capability for cell division in the cortex
parenchyma. This is explained as a vital adaptation to its life form.
Based on the extraradical mycelium, the mode of penetration, the structurally incompatible intraradical phase, the presence of intercellular vesicles in the root cortex, and the occurance of immediate hyphal bridges from arbuscular mycorrhizal roots of neighboring plants, the mycorrhiza of V. truncata is described as an arbuscular mycorrhiza (AM), although the characteristic arbuscles are missing. Special features of the AM in V. truncata are interpreted as an improved efficiency in taking advantage of the mycorrhiza.
Root connections with roots of neighbouring plants are common and preferred locations for fungal infections. An evolutionary tendency towards parasitism of higher plants is discussed.
Keywords: Voyria, Gentianaceae, AM, mycotrophy, heterotrophy, phylogeny.