| 从胚胎发育和解剖结构讨论红豆杉科的系统位置 |
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| 引用本文： | 王伏雄,陈祖铿,胡玉熹.从胚胎发育和解剖结构讨论红豆杉科的系统位置[J].中国科学院研究生院学报,1979,17(3):1-7. |
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| 作者姓名： | 王伏雄 陈祖铿 胡玉熹 |
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| 作者单位： | (中国科学院植物研究所) |
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| 摘 要： | 红豆杉科的原胚发育属标准型，除榧树属兼具裂生多胚外，其他各属均为简单多胚。多数
属的雌配子体经8或9次分裂后形成细胞。本科木材的交叉场纹孔多属柏木型，稀为杉木型；
无射线管胞，树脂道缺如。树皮中除澳洲红豆杉属尚未观察外，其余4属均具含晶韧皮纤维。
根据上述胚胎和解剖学特征，红豆杉科成立为一个自然群是不成问题的。但Florin只根
据“胚珠单个、顶生”而把它们提升到“目”一级的分类单位，与松柏目并列，从胚胎和解剖学资 料看，是不适当的。我们认为红豆杉科的系统位置，应该置于松柏目之下。
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On the systematic position of Taxaceae from the embryological and anatomical studies |
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| Wang Fu-Hsiung,Chen Zu-Keng,Hu Yu-Shi.On the systematic position of Taxaceae from the embryological and anatomical studies[J].Journal of the Graduate School of the Chinese Academy of Sciences,1979,17(3):1-7. |
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| Authors: | Wang Fu-Hsiung Chen Zu-Keng Hu Yu-Shi |
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| Institution: | (Institute of Botany, Academia Sinica) |
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| Abstract: | Florin has suggested that the Taxaceae should be separated from the Coniferales
to erect an order of its own. His basic argument is that the ovule of the taxads is
terminal while the ovules of the conifers are lateral. Florin's idea was accepted by
many taxonomists and some of them make an even higher taxon as Taxopsida. The
present paper deals with the systematic position of Taxaceae from the embryological
and anatomical studies in comparison with those of other members of the Coniferales.
The extant Taxaceae includes five genera, namely, Taxus, Pseudotaxus, Austro-
taxus, Amentotaxus and Torreya.
The mature pollen grains of Taxaceae contain two ceils (Torreya) or one cell only
(Taxus, Pseudotaxus and Austrotaxus). No prothailial cells are formed. Two sperms
are of unequal size. The number of free nuclei formed in the female gametophyte is
256(-512). The arehegonia vary from I to 25, with 2 to 8 as the usual range. The
proembryo of Torreya forms 4 or 8 free nuclei, while all other genera of the Taxaceae
usually contain 16(-32). Cleavage polyembryony is present in Torreya, but absent
in other genera. The proembryogeny belongs to the standard type of the Coniferales.
The bark of the Taxaceae possesses erystalliferous fibers. No crystals are formed
in parenehyma Rays are homogeneous and consist of ray parenchyma cells only.
Growth rings of the wood in Taxaceae are distinct. Axial tracheids with bordered
pits usually uniseriate, occasionally paired or biseriate, with spiral thickenings. Wood
parenchyma is present in Amentotaxus and Austrotaxus, but absent in Pseudotaxus,
Taxus and Torreya. Cross-field pits cupressoid. Resin canals and ray tracheids are
absent.
Considering Taxaceae as a natural taxon each of the main embryological and
anatomical characters is to be seen in other families of the Coniferales though the
combination is unique, making it a distinct family. Many differences between Taxa-
ceae and other families of the Coniferales fall within the range of the variation in the
conifers. However, Pinaceae is a rather specialized family among the Coniferales.
Thus, the difference between Taxaceae and Pinaceae is quite striking.
Florin agreed with Wilde (1944) that some species of Podoca rpus with single
ovule are derived from that with multiple ovulate cone and represent the last stage
of reduction of the cone. On the other hand, the taxads with their terminally borne
ovule are considered as primitive. It is obvious that Florin's explanation is hardly
convincing. Many authors such as Chamberlain (1935), Takhtajan (1953) and others
pointed out that single ovulate cone of the Taxaceae was very probably derived from
the one with multiple ovulate cone. Recently Keng (1969) considered that the
Taxaceae is closely related to Cephalotaxaceae on one hand and connected with the
Podocarpaeeae by way of Phyllocladus on the other hand. It is concluded that Florin's
suggestion is not supported by our investigations based upon the embryological and
anatomical features ef the Taxaceae by comparing them to those of other families of
the Coniferales. The systematic position of the Taxaceae should be placed under theConiferales. |
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