PITH AUTOLYSIS IN HERBACEOUS DICOTYLEDONOUS PLANTS - A PHYSIOLOGICAL ECOLOGICAL STUDY OF PITH AUTOLYSIS UNDER NATIVE CONDITIONS WITH SPECIAL ATTENTION TO THE WILD PLANT IMPATIENS-CAPENSIS MEERB

Pith autolysis, in the past studied only in herbaceous cultivated dico tyledonous plants, commonly occurs in wild plants. A survey of pith au tolysis in wild plants was conducted in several different biomes in bo th North Carolina, USA and in Belgium. An objective method and a subje ctive method were developed and used to estimate the amount of pith au tolysis in the internodes of bean (Phaseolus vulgaris L.) and the wild plant jewelweed (Impatiens capensis Meerb.) under experimental condit ions. A ranking system also was used to quantify pith autolysis in oth er wild plants. In the field, a positive correlation was found between the rate of internode elongation and pith autolysis. Injections of su crose solution were found to reduce the amount of pith autolysis devel oped in the upper internodes of jewelweed when compared to injections of control solution. Extracts from the nodal tissues of jewelweed incr eased the amount of pith autolysis developed by both jewelweed in the field and bean in the greenhouse. This increase in pith autolysis may be due to a principle present in the jewelweed nodes that signals or c auses the internodes to become hollow. (C) 1995 Annals of Botany Compa ny