Structure of Stems in Relation to Differentiation and Abortion of Blossom Buds

Abstract

Plants of Salvia splendens, Xanthium echinatum, Cosmos sulphureus, Mathiola incana, and Glycine max were either induced to flower or kept vegetative by means of appropriate photoperiod and temp. environments. Glycine and Salvia require 9, Cosmos 12, and Xanthium 5 days of short-day treatment for the initiation of blossom primordia. Stock is a long-day plant and requires about 18 long, cool days for appearance of blossom primordia. Previous observations showed that the anatomical structure of stems of plants in flower was different from those kept vegetative. From observations made on the above list of plants it was found that alterations in the anatomical structure of stems occur before or at least as early as the formation of blossom primordia. These structural changes are a decrease in number of cambial cells with a resulting decrease in the formation of vascular tissue. The cell walls of the vascular tissue become thicker-walled. If the plants are not kept in an environment favorable for blossoming for a greater length of time than just the induction period the structural changes do not persist. In this case the cambium resumes its activity; xylem and phloem cells are differentiated, and the blossom primordia fail to develop into buds.