Abstract
The stems from etiolated seedlings of Sorghum bicolor were separated into epidermal and endodermal fractions by manually removing the stele from the cortex. The epidermal fraction was shown to contain a lipid polymer whose monomeric composition was characteristic of cutin with dihydroxyhexadecanoic acid as a major component (25%). The endodermal fraction contained a lipid polymer whose monomeric composition was characteristic of suberin: hexadecanoic acid 12%, octadecenol 6%, octadecenoic acid 23%, omega-hydroxyhexadecanoic acid 17%, hexadecanedioc acid 8%, omega-hydroxyoctadecenoic acid 8%, and octadecenedioic acid 12%. This endodermal polymer is thought to be the suberin component of the Casparian band.