Untreated, intact plants of Mirabilis jalapa showed vigorous growth of the main axis with neither abscission nor the formation of an abscission zone in internodes during the period of these experiments. 2. Plants decapitated in the upper portion of the first internode when the second internode had just started to elongate and given no additional treatment showed cessation of growth in the internodes, followed by their abscission after 2 weeks or longer. Preceding abscission, two transverse meristems developed. The upper formed across the base of the internode and developed into the zone in which abscission occurred. The lower meristem, invariably present when the upper developed, seemed to play no active role in the process of abscission. Relatively little storage starch remained in the cotyledonary nodal region of these plants at 2 weeks after decapitation. 3. Plants similarly decapitated and treated with a 2% indoleacetic acidlanolin mixture on the cut surface showed continued growth of the internodes, complete disappearance of stored starch, and the entire absence of abscission or of an abscission zone at the bases of the internodes.
No takes yet. Share an insight, caveat, or question.
Beal et al. (1945) studied this question.