Vesicular‐arbuscular Mycorrhizae From the Triassic of Antarctica

Silicified roots from the Triassic of Antarctica show features of extant vesicular‐arbuscular mycorrhizae (VAM). Nonseptate fungal hyphae occur within and between well‐preserved parenchymatous cells of the central cortex. Terminal and intercalary swellings comparable to chlamydospores and vesicles are also present within the roots. In addition, three‐dimensionally branched structures nearly fill the host cell and resemble modern day arbuscles. Although possible mycorrhizae have been reported as early as the Devonian, and are widely accepted, fossil arbuscles, the most definitive feature of VAM, have not been previously described. The fungi associated with the Antarctic roots provide the most complete and convincing evidence for pre‐Pleistocene VA mycorrhizae in the fossil record.