Taxonomic implications of phenolic variation in leaves of birch (Betula L.) species

The phenolic composition of the seedling leaves of 10 birch species was compared. The results fit rather well to the infrageneric classification proposed for birches, except for B. schmidtii, which exhibited a flavonoid composition similar to white birches. Among white birches, differences in phenolic profiles were small, except for B. pubescens, which contained several flavonoids not detected in other species. Qualitative chemotypes were distinguished from five species, and in white birches they were mostly based on presence or absence of the same compounds. The results support the view that the diploid white birches form a continuum of closely related taxa. (C) 1999 Elsevier Science Ltd. All rights reserved.