Sources of Carbohydrate for Germination and Growth of Orchid Seedlings

Ever since 1840, when Linck observed the endophytic fungus in orchid roots, the symbiotic relationship between these interesting plants has been studied by mycologists, plant physiologists, and horticulturists.We may roughly divide the research that has been done since 1840 into two main periods.The first period consisted in efforts to verify the universality of the endophytie infection and to link this mycorrhizal condition with various phenomena of germination.Wahrlich (786) was the first to establish the generality of the occurrence of the endophyte.He examined the roots of five hundred species of orchids and found all to be contaminated with a fungus which he held to be species of Nectria.Since the time of Wahrlich, the taxonomy of the fungal symbiont has passed through a complex and varied evolution, but a discussion of this phase of orchid research is beyond the scope of the present paper.The existence of the endophyte was further verified by Prillieux (756, '60), Prillieux and Rivière (56), and by Fabre (756).Bernard (700) early suspected the relationship between the germination of orchid seeds and the presence of the endophyte.He obtained good germination on sawdust which was kept in the same greenhouse as the parent plants, and pointed out that this was probably due to an infection of the sawdust by the fungus from the parent plants.The publication of these results was followed by a number of other papers (702, '03, '04, '06),