THE ORIGIN AND DEVELOPMENT OF THE PHELLOGEN IN ROBINIA PSEUDACACIA L.

Abstract

The ontogenetic development of the phellogen in Robinia pseudacacia plants was studied. The first phellogen differentiates in the seedling stage from collenchyma cells in the second or third layer beneath the epidermis. The subsequent phellogen is periodically derived from phloem parenchyma cells. The site of phellogen initiation was shown to be affected by climatic conditions as well as by various growth substances. Under long‐day and high‐temperature conditions the phellogen was initiated in a lower internode, as compared with plants grown under the other three combinations of photoperiod and thermoperiod, Gibberellic acid and naphthalene acetic acid had distinct retarding effects on initiation Kinetin and tri‐iodo‐benzoic acid treatments showed no effect. Copyright © 1968, Wiley Blackwell. All rights reserved