Wybrane zagadnienia z morfogenezy liści drzew. II. Występowanie młodocianych form liści w koronach drzew buka zwyczajnego (Fagus silvatica L.) [Studies on the mohprogenesis of tree-leaves. II. The occurrence of juvenile forms of leaves in the crowns of beech trees (Fagus silvatica L.)]

It was fairly often observed that Fagus silvatica L. leafed twice during one vegetational season. This secondary growth occurred on all trees, when the first leaves underwent destruction, e.g. in consequence of late spring frost. The leaves of secondary growth differed pronouncedly from normally developed ones by their shape and irregular nervation and were similar to the juvenile leaves of one-year-old seedlings of beech. Observations of leaf buds showed that the nerves appeared in leaf-primordia of Fagus silvatica as late as the latter part of July and if the secondary leaves developed at the end of July, they were normal in shape and bad regular nervation. Leaf-primordia compelled to an earlier development gave leaves of different form and irregular nervation