Cladonia rangiferina(L.)Wigg.,Cladonia mitisSandst., andUmbilicaria muhlenbergii(Ach.) Tuck, were extracted with acetone while damp and after three different drying procedures. The extracts were chromatographed and scanned spectrophotometrically. Some of theC. rangiferinacompounds were not extractable from damp material. All of the lichen substances studied here decreased significantly in thalli which were dried in an oven at 80 deg;C, some to the point of imperceptibility. There was no qualitative difference between the complement of compounds found in lichen material dried at 22 deg;C and at 40 deg;C. We recommend that drying be carried out at a temperature not exceeding 40 deg;C. Chemical variability among thallus regions of different ages was studied inCladonia rangiferina, C. mitis, Umbilicaria muhlenbergii, andLasallia papulosa(Ach.) Llano. Fumarprotocetraric acid, atranorin, and usnic acid were present in significantly higher amounts in younger tissue than in older. Protocetraric acid inC. rangiferinawas detectable only in the older portions and would have been overlooked if young branches had been analyzed exclusively. In neither of the two umbilicate lichens was there any significant difference in the concentration of gyrophoric acid between younger and older thallus parts. Chemical variability among different-aged thallus parts was thus greater in the fruticose species than in the umbilicates examined here.
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