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The biology and the life cycle of the fungus Endogone (Glomus; see gerdemann and Trappe) the cause of vesiculararbuscular (V—A) mycorrhiza was investigated in relation to two host plants; Festuca ovina and Alliuim cepa. Although much studies have been done about this type of mycorrhiza, most of these have been centered around the ecological and nutritional relationship between the endophyte and its hosts. Very little work has been done to understand its life cycle. Particular problems facing the investigators in this respect have been the lack of germination of spores and growth of the fungus in the laboratories under artificial conditions and the establishment of some stages in the life cycle of the fungus apart from the host.
This investigation reveals for the first time that seven marked and distinguishable phases can be observed in the life cycle of the fungus. These are; (I) the germination of chlamydospores, (2) the establishment of extrametrical mycelium, (3) the direct epidermal penetration phase, (4) growth of internal mycelium, (5) formation of arbuscules, (6) formation of vesicles, and (7) extra-matrical mycelium and formation of chlamydospores.