CUTICULAR STRUCTURE OF TWO ANGIOSPERM FOSSILS IN NEOGENE FROM TENGCHONG，YUNNAN PROVINCE AND ITS PALAEOENVIRONMENTAL SIGNIFICANCE
CUTICULAR STRUCTURE OF TWO ANGIOSPERM FOSSILS IN NEOGENE FROM TENGCHONG，YUNNAN PROVINCE AND ITS PALAEOENVIRONMENTAL SIGNIFICANCE
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发表时间：
2003
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通讯作者：
S. Nian;C. Yun;Yan Fei;Xie Sanping
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作者：
S. Nian;C. Yun;Yan Fei;Xie Sanping
本文着重描述了采自云南腾冲新近纪的两种被子植物化石Betula mioluminifera Hu et Chaney和Carpinus subcordata Nathorst的表皮特征。其近亲物种（NLR 物种）、Betula luminifera Winkler 和 Carpinus cordata B1.var 的表皮特征。 mollis Cheng 等人进行了分析。本实验获得了C.subcordata的下表皮，其特征如下：仅保留叶的中、下部分；长约7.5厘米，宽约5厘米。中脉强健；腹腔与中脉夹角40°—50°；越靠近底座，角度越大；微静脉，多于12对。上表皮稍厚，脉网状，无气孔；表皮细胞排列圆形，多角形，长宽20～30μm；网的长度约350μm，宽度约200μm；神经走行宽度50μm，平行细胞3—4排；神经管内的细胞呈长圆形，长度约为宽度的2-3倍。下表皮薄，有气孔；发现毛状体；表皮细胞的排列与上表皮相同。气孔分布无规则；气孔器类型 Anomocytic;气孔稍凹陷；保卫细胞呈肾形，略低于周围细胞；保卫细胞内表面厚；保卫细胞被数个表皮细胞包围。角质层及其气孔代表了植物与大气的界面，其角质层厚度、气孔密度（SD）、气孔指数（SI）和气孔比（SR）等特征被很好地用作古环境指标。因此，我们可以通过研究对大气CO 2 浓度变化敏感的化石植物的气孔参数来分析古环境的变化。在本实验中，我们得到了C.subcordata的气孔参数，这表明新近纪大气CO 2 浓度高于今天。通过比较C.subcordata与其NLR C.cordata的表皮特征，我们得出结论：滇西新近纪气候温暖湿润，属热带至亚热带或暖温带。此外，C.subcordata和B.mioluminifera也存在同样的特征，其表皮细胞均呈圆形排列。这可能是桦科植物的特性，也可能是植物叶片中细脉过多造成的现象。预计未来将得到证明。综上所述，C.subcordata的叶子可以作为古大气CO 2 浓度的生物指示剂。
This paper emphatically describes the cuticular characteristics of two fossil angiosperm species Betula mioluminifera Hu et Chaney and Carpinus subcordata Nathorst collected from Neogene in Tengchong, Yunnan. The cuticular characteristics of their Nearest Living Relative species (NLR species), Betula luminifera Winkler and Carpinus cordata B1.var. mollis Cheng et Chen, are analysed. In this experiment, we have got the lower epidermis of C.subcordata, whose characteristics are described as follows: Only the middle and lower parts of leave preserved; length about 7.5 cm, width 5 cm. Midrib strong; angle between ventricumbent and midrib 40°—50°; nearer to the base, bigger the angle; venulose, more than 12 pairs. Upper epidermis a little thicker and net-veined, stomata not found; epidermic cells arrayed rotundly, polygonal, length and width 20—30 μm; length of the net about 350 μm, width about 200 μm; width of nervecourses 50 μm with 3—4 rows of parallel cells; cells in nervecourses oblong, length about 2—3 times of width. Lower epidermis thin with stomata; trichome found; arrangement of epidermic cells as the same of upper epidermis. Distribution of stomata ruleless; type of stomatal apparatus Anomocytic; stomata slightly sunken; guard cells kidney-shaped and slightly lower than surrounding cells; inner surface of guard cells thick; guard cell surrounded by several epidermic cells. The cuticle, with its stomatal pores, represents the interface between plants and atmosphere, and its features such as cuticle thickness, stomatal density (SD), stomatal index (SI) and stomatal ratio (SR) are well used as a palaeoenvironmental indicator. Therefore, we can analyse changes in palaeoenvironment by studying the stomatal parameter of fossil plants which are sensitive to the change in atmospheric CO 2 concentration. In this experiment, we have got the stomatal parameter of C.subcordata which indicates that atmospheric CO 2 concentration in Neogene was higher than that of today. By comparing the cuticular characteristic of C.subcordata with that of its NLR, C.cordata, we concluded that the Neogene climate in western Yunnan was warm and humid, belonging to tropical zone to subtropical zone or warm temperate zone. In addition, the same feature exsists in C.subcordata and B. mioluminifera, whose epidermic cells are all arrayed as rotundity. This maybe is the characteristic of Betulaceae, or the phenomenon due to excess of veinlet in plant leave. It is expected to be proved in the future. From this brief review, the leaf of C.subcordata may be taken as a bio-indicator of palaeoatmospheric CO 2 concentration.