Despite the considerable effort expended in the exploration of alternative, large-scale sources of eicosanoids, the first-discovered nonmammalian source--the gorgonian Plexaura homomalla--remains by far the most impressive. The evolutionary reasons for the huge concentrations of prostaglandins in this coral and the origin of the dependence of C-15 configuration on geographical location still constitute fascinating areas for speculation and research. Although the coral provided an extremely valuable interim source of prostaglandins between the eras of biosynthesis and total chemical synthesis, the best of the many synthetic routes now available offer the advantages of versatility and unlimited scale-up potential, and are economically competitive as well. Partial synthesis from various readily available iridoid glycoside intermediates still appears to be an attractive alternative for the preparation of selected eicosanoids. The discovery of unusual eicosanoids such as hybridalactone and the clavulones demonstrates that the oxidative metabolism of C20 unsaturated fatty acids may be considerably more complex than yet realized. The discovery of additional structurally novel, biologically significant eicosanoids from both animal and plant sources can be predicted with virtual certainty. Given the low levels of C20 unsaturated fatty acids in most plants, it is not surprising that the levels of oxidized eicosanoids (e.g., prostaglandins) observed to date in plants have also been very low. The levels were sufficient, however, to dispel the long-popular notion that prostaglandins existed only in the animal kingdom. Plants such as the mosses and ferns mentioned earlier (3,55), which contain unusually large amounts of arachidonic acid, seem to be particularly promising species in which to search for additional novel eicosanoids. In addition to new structures, further information regarding the physiological role of eicosanoids in plants will undoubtedly be forthcoming.