Epipogium aphyllum is a rare European obligate mycoheterotrophic orchid lacking chlorophyll. It has not been studied previously with respect to pollination biology. We studied the association between the composition of floral scent emission and its pollination systems. Field observation indicates that the main pollinators of Epipogium aphyllum are representatives of the genus Bombus (Hymenoptera), B. lucorum, B. hortorum, B. terrestris, B. pascuorum and B. proteus, and the genus Apis (Hymenoptera) namely A. mellifera. The main potential vector (observed to accidentally carry pollen), is most likely Episyrphus balteatus (Diptera, Syrphidae). The chemical composition of the floral extracts of 4 populations of Epipogium aphyllum Sw. growing naturally in Poland and the Czech Republic was examined by gas chromatography coupled with mass spectrometry (GC-MS) and high-performance liquid chromatography coupled with diode-array detection and electrospray ionization mass spectrometry (LC-ESI-MS) techniques. According to GC-MS analysis, 9-tricosene, nonadecane, 1-nonadecene and nonacosane predominated in the floral extracts. The studied samples were also characterized by relatively high amounts of benzenoids, e.g. methyl cinnamate, which is known as an attractant to the males of various orchid bees. LC-ESI-MS revealed the presence of flavor compounds such as vanillin (4-hydroxy-3-methoxybenzaldehyde) and its derivative acetovanillone, together with higher amounts of aliphatic and phenolic acids. Additionally, we detected the presence of indole and morphine derivatives.

Epipogium aphyllum is a European-Asian obligatory mycoheterotrophic orchid containing no chlorophyll. Flowers are not resupinate with a sack-shape spur and cordate lip, which is divided into two parts: the basal (hypochile) and distal one (epichile). The floral analysis provides strong evidence to conclude that nectar is secreted on the upper surface of pink-coloured papillate ridges and epidermal (adaxial) cells at different place in spur, especially at the apex. The exudation on papillae has been observed through the entire anthesis and it has been stained on polysaccharides, proteins, and lipids. The dense cytoplasm of papillae contains profuse endoplasmic reticulum, plentiful vesicles (bigger ones with tannin-like materials), numerous mitochondria, sometimes dictyosomes, starch grains, and plastids with tubular structures. The large electron-dense bodies in cell walls are structurally the same as tannin-like materials from vesicles that are in contact with plasmalemma. The rupture of thin layer of swelled cuticle is caused by pressure of gathered substances exuded due to granulocrine secretion. The idioblasts with raphides occur mainly in tepals tissue. The dynamic changes of the nectar exudation, released through endocrine secretion, have been noticeable during the anthesis: both on the lip and inside the spur. The nectar secretion is not dependent on the colour form of E. aphyllum blooming shoots. The floral biology and ultrastructure differ from mycoheterotrophic plants known up to date.