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In New South Wales P. xanthopus is limited to an area of 70 by 10 km, about 150 km north-east of Broken Hill. The distinctive habitat consists of cliffs, wind-blown caves and angled boulders jumbled together. The temperature and relative humidity differed by 11�C and 21 % between the outside and the inside of one cave. The vegetation is abundant and diverse, and indicates a moisture regime more favourable to the species than is that of the surrounding plain. The conservation of the species is discussed.

Seed was collected from jojoba [Simmondsia chinensis (Link) Schneider] plants growing at three field sites in two years. The wax percentage was determined by nuclear magnetic resonance and the compositions of the wax and the ethanolysis products (one site only) were determined by gas chromatography. The mean wax concentration varied from 49.2 to 55.1% over all sites and years. The percentage of long-chain wax esters (>C40) decreased linearly with increase in mean maximum temperature during the period of linear seed growth (r� = 0.93). The decrease in long-chain esters was associated with a decrease in the C22 and C24 fatty acids and alcohols. Data from controlled environment studies and from field studies were used to assess the effect of temperature on the percentage elongation, reduction and esterification of acyl-CoAs of carbon lengths 18-22. High temperature lowered the specificity for elongation of C20-C22 and of C22-C,24 and increased the specificity for reduction of the C20 acid to its corresponding alcohol. The amount of C42 wax ester was greater than would be expected by random association of the alkoxy-acyl groups but this preference was not as great at high temperatures.

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