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Ergosterol peroxide (ep), synthetic or from fungal extracts, is shown to be a mixture of isomers arising from α- and β-attack by O 2(1Δg) on ergosterol; the stereochemistry of the peroxide bridge is assigned.

The structure of hircinol, a phytoalexin isolated from Loroglossum hircinum has been established as 2, 5-dihydroxy-4-methoxy-9,10-dihydrophenanthrene. This phytoalexin, the second to be identified in the Orchidaceae, is less effective than orchinol, and its isomeric co-metabolite, loroglossol, 5-hydroxy-2,4-dimethyoxy-9,10-dihydrophenanthrene, is inactive. © 1973.

Summary: Leaf‐tips of Epidendrum and Laeliocattleya (Orchidaceae) have been cultured in vitro. Epidendrum seedling leaf‐tips form calli on Murashige‐Skoog medium (MS) or after being transferred to Knudson C agar following prior growth on MS. Plantlets also develop from tips of young leaves of mature Laeliocattleya plants cultured in Heller's medium or in a solution specifically devised for orchid shoot‐tip cultures. In Heller's medium plantlet development is preceded by callus formation whereas in the shoot‐tip medium protocorm‐like bodies are formed first. These tissues when subcultured from Heller's medium or the shoot‐tip solution to Knudson C agar also produce plantlets which resemble orchid seedlings. The results are discussed in relation to the components of each medium, the requirements of germinating orchid seeds and protocorms, and the difficulties encountered in attempts to culture tissues of mono‐cotyledonous plants.

The effects of sugars and other carbohydrates, vitamins, hormones, complex additives, temperature, light, pH, atmosphere and its components, and moisture are reviewed. Orchid mycorrhiza, symbiosis and asymbiotic nutrition are also reviewed.

Ergosterol '5β,8β-peroxide' has been identified as 9,11-dehydroergosterol peroxide.