THE CAMBIUM AND SEASONAL DEVELOPMENT OF THE PHLOEM IN ROBINIA PSEUDOACACIA
THE CAMBIUM AND SEASONAL DEVELOPMENT OF THE PHLOEM IN ROBINIA PSEUDOACACIA
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DOI：
10.1002/j.1537-2197.1967.tb06903.x
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发表时间：
1967-02
影响因子：
3
通讯作者：
W. F. Derr;R. Evert
中科院分区：
文献类型：
--
作者：
W. F. Derr;R. Evert
刺槐的形成层始终由多层细胞组成。形成层再活化（分裂）之前是形成层细胞原生质体密度降低和细胞壁增厚，但不是细胞扩大。在形成层活动恢复期间，整个形成层区发生平周分裂。早期分裂主要发生在韧皮部一侧。形成层最活跃的时期与早期木材形成相一致。根据两个季节（1960年10月至1962年10月）的大量采集，韧皮部发育的季节循环如下。韧皮部分化始于4月上旬，结束于9月下旬。产生的韧皮部的数量是相当可变的（范围：每年1-10个筛分子带）。功能的停止开始于在第一次形成的筛分子中的最终胼胝质的积累，并扩展到最近形成的筛分子。到11月下旬，除了最后形成的筛元件外，所有的筛元件都崩溃了。所有的筛分子在冬季中期和春季新韧皮部生产恢复之前都崩溃了。韧皮部分化先于木质部分化至少1周，并且明显功能性的筛元件在新的功能性导管元件之前3周存在。在大多数树木中，木质部和韧皮部的产生同时结束。
The cambium in black locust consists of several layers of cells at all times. Cambial reactivation (division) is preceded by a decrease in density of cambial cell protoplasts and cell wall thickening but not by cell enlargement. During the resumption of cambial activity, periclinal divisions occur throughout the cambial zone. Early divisions contribute largely to the phloem side. The period of greatest cambial activity coincides with early wood formation. Judged by numerous collections made during two seasons (October, 1960-October, 1962) the seasonal cycle of phloem development is as follows. Phloem differentiation begins in early April, ends in late September. The amount of phloem produced is quite variable (range: 1-10 bands of sieve elements per year). Cessation of function begins with the accumulation of definitive callose in the first-formed sieve elements and spreads to those more recently formed. By late November all but the last-formed sieve elements are collapsed. All sieve elements are collapsed by mid-winter and before the resumption of new phloem production in spring. Phloem differentiation precedes xylem differentiation by at least 1 week, and apparently functional sieve elements are present 3 weeks before new functional vessel elements. Xylem and phloem production ends simultaneously in most trees.