Fatty acids with conjugated unsaturation occur in many seed oiIs. Thirty of these acids are reviewed with emphasis on their detection, isolation, and structure determination. Their distribution among plant families is shown, and a botanical source of each acid is given. Some reactions, derivatives, and methods of determining configuration are described. Current theories of their biosynthesis in the seed, involving oxygenated precursors, are summarized.

The seed oils of 11 species ofSapindaceae were examined, and their fatty acid composition was determined.cis-11-Eicosenoic acid was identified as the major fatty acid ofKoelreuteria paniculata. It was present in nine of the 11 species in amounts from 8-60% of the total fatty acids and is evidently a common component of oils of this plant family. Arachidic acid was present in amounts up to 11%. Only three of the oils had acids of chain length greater than C-20. Seed oils of certain species ofKoelreuteria andCardiospermum are good potential sources of 11-eicosenoic acid.

Mixed pollen, gathered by honey bees, contained a free fatty acid which was isolated and identified as octadeca-trans-2,cis-9,cis-12-trienoic acid. The acid was shown to be an attractant for the honey bee. It is evidently produced by the plant and acts as a food marker for the insect.

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The seed oil of Tragopogon porrifolifoliz~s I,. was found to contain about 4y0 of conjugated diene hydroxy fatty acids, identified as 9-hydroxy-10,12-and 13-hydroxy-9,ll-octadecadienoic acids. On dehydration, the products were 8,10,12-and 9,11,13-octadecatrienoic acids. The diene acids were cis,trans or lra?rs,cis and the trierle acids were judged to be all-trans.The conjugated triene acid of Calendr~la ofici?zalis L. seed oil was isolated and identihed as trans,8:trans,l0:cis,12-octadecatrienoic acid by spectral analysis, by the structure of the il~aleic anhydride adduct, and by ideiltification of degradation products. All-tra?rs-8,10,12-octadecatrienoic acid was found to react with rnaleic anhydride a t both the 8.11 and 10,13 positions.