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The fatty acid, sterol and hydrocarbon compositions of the fresh leaves from eleven species of mangroves, cultivated in a shadehouse, are reported. The fatty acid and sterol analyses, whilst generally typical of higher plants, showed several chemotaxonomically significant differences between the species. The epicuticular wax hydrocarbons and fatty acids were low in abundance compared to previous reports of mangrove leaf lipids, which may reflect the importance of environmental influences on this group of compounds. Cluster analysis of selected subsets of the data showed clear chemotaxonomic divisions amongst the mangroves. The results grouped the mangroves into genera, except for the Rhizophora and Ceriops tagal which were not separated, and grouped the family Rhizophoraceae distinct from all other species except Xylocarpus granatum. Avicennia marina var. resinifera was able to be distinguished from Avicennia marina by cluster analysis, supporting its assignment as a distinct variety. The results show that the lipids of mangroves are chemotaxonomically significant.

The sterol and fatty acid compositions of fresh leaves of the seagrasses Cymodocea serrulata , Enhalus acoroides , Halodule uninervis , Halophila ovalis , H. ovata , H. spinulosa and Thalassia hemprichii are reported. The major fatty acids were palmitic acid, linoleic acid and linolenic acid as expected. H. ovalis and H. ovata were characterized by the relatively high abundance ( ca 5%) of the acid hexadeca-7,10,13-trienoic acid (16:3 ). The sterol compositions were typical of higher plants, with sitosterol and stigmasterol accounting for 60–90% of the observed sterols. 28-Isofucosterol was a major sterol (20–30%) only in the Halophila spp. Cluster analysis of the sterol composition data clearly separated the Halophila spp. from the other seagrasses and enabled the distinction of Enhalus sp. from Cymodocea , Halodule and Thalassia spp. The seagrass species were clearly separated into five chemical groups using the combined fatty acid and sterol composition data and the need for a reappraisal of the taxonomic position of Halophila was indicated.

Zonarene (II) and its epimer (I) have been identified as constituents in nine essential oils. Their structures and absolute configurations are established through chemical interrelationship with amorphenes and circular dichroism studies. Diene I occurs in both enantiomeric forms in nature.

Two new sesquiterpene hydrocarbons, bicyclosesquiphellandrene and 1-epibicyclosesquiphellandrene have been isolated from Piper cubeba oil and Ocimum basilicum oil respectively. Their structures were elucidated spectroscopically and their stereochemistry by acid rearrangement and hydrogenation studies.