In 1975 some higher herbaceous plants of two different habitats were investigated according to seasonal variations of their caloric values both on a dry weight base and on an ash-free dry weight base. In eight speceis of a meadow and an old-field community, which were harvested each second month from February to December 1975, there were slight changes in energy content despite the fact that only flowering stages have been analysed. The reasons for these variations are climatic resp. endogenous ones.