SEASONAL DEVELOPMENT OF SECONDARY PHLOEM IN POPULUS TREMULOIDES
SEASONAL DEVELOPMENT OF SECONDARY PHLOEM IN POPULUS TREMULOIDES
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DOI：
10.1086/336406
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发表时间：
1968-01-01
影响因子：
--
通讯作者：
EVERT, RF
中科院分区：
文献类型：
--
作者：
DAVIS, JD;EVERT, RF
从1年期间（1962年4月至1962年8月）的大量收藏来看。（1963），杨树韧皮部发育的季节循环如下。形成层的活动（分裂）开始于3月底或4月初，主要产生筛元、伴细胞和薄壁细胞的组合。到5月中旬，大约一半的新韧皮部生长已经产生。7月底或8月初筛元分化完成。在9月下旬或10月初，随着传导韧皮部外缘筛子中决定性胼胝质的形成，功能开始停止。到11月下旬，所有筛元都没有内容物，它们的伴生细胞塌陷。韧皮部分化早于木质部分化，开始于5月中旬，大约早一个半月；木质部和韧皮部的分化几乎同时停止。
Judging from numerous collections made over a 1-year period (April, 1962-Aug., 1963), the seasonal cycle of phloem development in Populus is as follows. Cambial activity (division) begins in late March or early April, giving rise primarily to assemblages of sieve elements, companion cells, and parenchyma cells. By mid-May about half of the new phloem increment has been produced. By the end of July or early Aug. sieve element differentiation is completed. Cessation of function begins in late Sept. or early Oct. with formation of definitive callose in sieve elements on the outer margin of the conducting phloem. By late Nov. all sieve elements are devoid of contents and their companion cells collapsed. Phloem differentiation precedes xylem differentiation, which begins in mid-May, by approximately a month and a half; xylem and phloem differentiation ceases almost simultaneously.