| 白豆杉的胚胎发育及其系统位置的商榷 |
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| 引用本文： | 陈祖铿,王伏雄.白豆杉的胚胎发育及其系统位置的商榷[J].中国科学院研究生院学报,1978,16(2):1-10. |
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| 作者姓名： | 陈祖铿 王伏雄 |
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| 作者单位： | (中国科学院植物研究所) |
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| 摘 要： | 白豆杉属(Pseudotaxus Cheng)是我国裸子植物特有属之一，它的胚胎发育十分类似于红豆
杉属。白豆杉受精卵经4次有丝分裂，形成16个游离核的原胚，紧接着形成细胞壁。简单多
胚普遍存在，但没有裂生多胚。在后期胚胎发育中，根原始细胞主要向上分化形成原形成层和
胚皮层，向下提供根冠较少。因此，根冠组织弱小，而次生胚柄系统则十分发达。成熟胚具2
枚子叶，下胚轴中没有髓部，也没有任何分泌分子。
通过白豆杉胚胎发育的研究，作者认为白豆杉属在红豆杉科中的排列位置是：红豆杉属、
白豆杉属、澳洲红豆杉属、穗花杉属和榧树属。其中红豆杉属和白豆杉属比较原始，而榧树属
则比较进化。同时作者认为：从胚胎学资料看，将红豆杉科从松柏目中分离出来，单独成立红 豆杉目，这种观点得不到支持。
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Embryogeny of Pseudotaxus chienii in relation to its systematic position |
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| Chen Tsu-Keng,Wang Fu-Hsiung.Embryogeny of Pseudotaxus chienii in relation to its systematic position[J].Journal of the Graduate School of the Chinese Academy of Sciences,1978,16(2):1-10. |
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| Authors: | Chen Tsu-Keng Wang Fu-Hsiung |
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| Institution: | (Institute of Botany, Academia Sinica) |
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| Abstract: | The embryogeny of Pseudotaxus chienii Cheng, a member of Taxaceae, has been
investigated. Pseudotaxus is endemic to China and its distribution is restricted to
Lung-chuan County, Chekiang, Ching-kang Mountains, Kiangsi and Sze-ming Moun-
tains, Kwangsi. The material used for the embryological study was collected in 1964
from Lung-chuan, the type locality of Pseudotaxus.
Fertilization took place within the last week of May, 1964. The fertilized egg
undergoes four mitotic divisions in succession without wall formation and a proem-
bryo of 16 free nuclei is formed. Then the wall formation follows. The 16 cells of
the proembryo are arranged in two groups, the upper one being the open tier (O)
and the lower, the primary embryo cells (PE). The relative number of cells (O :PE)
is usually 9:7, occasionally 10:6 or 8:8, rarely 7:9. The cells in the open tier are
often not walled above. The division of the open tier results in the formation of the
upper tier and the prosuspensor. While the prosuspensor cells begin to elongate the
divisions of the primary embryo cells give rise to the embryo cells (12-18 cells).
Usually two archegonia in the same ovule are fertilized and two embryonal sys-
tems are developed. Thus, simple polyembryony prevails. In addition, several su-
pernumerary embryonic masses may be found above the prosuspensor cells but they
are usually ephemeral because of lack of sufficient nutrients in later stage. Cleavage
polyembryony is absent in Pseudotaxus.
A cap cell is usually formed at the apex of the young embryo. In later stages
of embryonal development root initials contribute mainly to the procambium and
embryonic cortex but less to the root cap. The embryo matured about the middle
of September, 1964. The mature embryo has two cotyledons. No pith is formed in
the central cylinder. No secretory elements are developed in any part of the embryo.
The suspensor is well developed and becomes massive while the root cap is rather
weak. The similarities in the embryogeny between Pseudotaxus and Taxus are very
striking. They have a similarity in the development and general structure of the
proembryo; cleavage polyembryony is absent while simple polyembryony prevails;
both have no pith and no secretory elements in the mature embryo.
Based upon the results obtained from the present investigation in Pseudotaxus
the authors consider that the systematic position of Pseudotaxus in Taxaceae may be
arranged as follows: Taxus, Pseudotaxus, Austrotaxus, Amentotaxus and Torreya.
Among them Taxus and Pseudotaxus are relatively primitive and Torreya is the most
advanced, while Austrotaxus and Amentotaxus are between. The embryological data
do not support the viewpoint of Florin that Taxaceae should be removed from Coni-
ferales and a parallel order Taxales should be established.
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