田麻属和平当树属的系统位置兼论椴树科与梧桐科的界限
唐亚
学位类型博士
导师吴征镒
1990
学位授予单位中国科学院昆明植物研究所
学位授予地点中国科学院昆明植物研究所
摘要田麻属和平当树属是东亚特有的两个少型或单型属,对这两个属的研究几乎是空白。在不同系统学者的处理中,田麻属属于椴树科或属于梧桐科,平当树属置于梧桐科或归入木棉科。本文从形态学、解剖学、孢粉学、细胞学和胚胎学方面对这两个属进行了研究,并和相关类群进行比较,以充分的证据论证了两个属的系统位置。此外,还根据资料探讨了椴树科和梧桐科之间的界限。一、田麻属的综合特征:花单生,雄蕊 5-15,1-3个一束,与5个舌状或条状的退化雄蕊相间着生于一轮,二者基部合生;子叶先端具缺刻;背腹叶,中脉维管束半圆形,叶柄维管束近环形;上下表皮具气孔,不规则型或不等细胞型;复管孔,由2或3个管孔组成,团状或径列,管孔数目很多,导管分子弦向直径30-55μ,长89-272μ,轴向薄壁组织少,射线单列,异型;花粉粒3孔,外壁具刺,球形;体细胞染色体数20,基数10;小孢子四分体四面体形,孢质分裂同时型,腺质绒毡型,绒毡层细胞二核,花粉散出时具二细胞;胚珠倒生,双珠被,厚珠心,外珠被2 层细胞厚,内珠被3层细胞厚,单细胞孢原为主,四分体线形,合点端大孢子发育,珠孔由内外两层珠被构成,反足细胞在胚囊中宿存至受精。通过上述综合特征与有关类群的比较,作者支持将田麻属作为梧桐科成员,但位于Dombeyeae族之后,是一独立的族。二、平当树属的综合特征:伞形聚伞花序,稳定的16枚雄蕊,3个一束,与5个舌状退化雄蕊相间着生,二者在基部结合成围绕子房的雄蕊筒,花被果时宿存,花药2室,子叶中央具缺刻;等面叶,中脉维管束2 束,弓形,叶柄维管束2 束,圆形;气孔限于下表皮,不等细胞型,稀短平列型;外各皮5-6层细胞厚,内各皮3-4层细胞厚;导管分子弦向直径54-83μ,长240-515μ,复管孔常由10-20个管孔组成,排列成显著的径列管孔链,管孔数量很多,轴向薄壁组织极少,单列及2-3细胞宽的射线,异型;花粉具3孔,外壁具刺,球形或近球形;体细胞染色体数20,基数10,核仁在前期 消失。根据上述特征,作者支持平当树属保留在梧桐科Dombeyeae中,是向田麻族过渡的类群。二、根据所收集到的资料,结合作者的一些观察研究,表明在椴树和梧桐科之间,形态学上有一不甚分明的界限,主要是雄蕊群的特征;细胞学上主要基数不同,椴树科主要为8和9,梧桐科主要为10;胚胎学的反足细胞存在时间不同,珠孔构成也不相同,即椴树科中反足细胞在胚囊形成后很快消失,珠孔通常由一层珠被构成,而梧桐科中反足细胞存在至爱精时,珠孔通常两层珠被构成或珠心裸露;在其它特征上两个科相似或有明显的过渡。各方面的综合特征表明两个科的界限不分明。尽管文中没袭传统概念将两个科视为独立的科处理,未来深入的研究可能会将二者合为一科。三、作者确认田麻属中有1 种1 变种,归并了1 种2变种,降级一种;平当树属2种,归并一种。
其他摘要The opinions about the systematic position of two genera Corchoropsis and Paradombeya are not accordant. Based on the little studies it is difficult to ascertain their systematic position. In more than two and a half years, studies have been carried out on the morphology, anatomy, palynology, oytology and embryology of these two genera. Descriptions of morphology, leaf anatomy, wood, pollen, chromosome, microsporogenesis, and macrosporogenesis are presented and comparisons are made to related taxa. The comprehensive results support their inclusin in the Sterculiaceae. One species and one variety in Corchoropsis and two species in Paradombeya are recognized. And lastly, the delimitation between Tiliaceae and Sterouliaceae has been briefly discussed. The more in detaial are given as follows. I. The systematic position of the genus Corchoropsis Morphology: Subshrub to herb, with dentate, simple and alternate stipulate leaves; flowers bisexual, axillary, solitary; bracteoles three and verticillate on the upper pedicel, deciduous; calyx 5-partite, petals 5, yellow, deciduous; stamens 5-15, 1-3 in cluster alternate with the 5 staminodes on the same whorl; ovary 3-locular, loculi 6-10-ovuled, placenta axile, style simple, subclavate, stigma 3-toothed; capsule siliquiform, cylindric, loculicidally 3-valved, with persistent reflexed calyx; seed small, cotyledon 2-lobed in the middle of the upper margin; indumentum stellate. WOOD: The arrangement of pores groups is mostly multiples of 2-3 cells, in cluster or in small radial chain, rarely solitary. Pore outline is elliptic. Tangential pore diameter averages 48u, with a range of 30-55u. Perforation plates are exclusively simple, gemerally with elliptic or round perforation. Vessel element length averages 198u, with a range of 89-272u. Intervascular pitting is alternate, 4.2u in diameter. Pits to ray are similar to intertascular pitting. Vascular rays are heterogeneous, uniseriate (Kribs Heterog. III), averages 17 per mm. with a range of 14 to 19 per mm., narrower than pores in transvorse seotion, ray height averages 0.85mm., ranging from 0.723mm to 1.00mm. Tile cells are numerous. Contents are observed in some preparations. Axial xylem parenohyma is very scanty. Regarding the wood anatomy, the arrangement of pores, pore size vessel element length and pore number per sq.mm.etc recall some Sterculiaceae, especially Byttnerioidae, but differ so much from Tiliaceae, in which the pore size is usually larger, the multiples consist of more cells, the pore number. pre sq.mm. is fewer. But there are some characteristics different from both Tiliaceae and Sterculiaceae, such as the uniseriate heterogeous ray(Kribs Heterog. III) and scantiness of axial xylem parenchyma. II The systematic position of the genus Paradombeya Stapf MORPHOLOGY: Shrub or a small tree, with serrate, stipulate, simple, alternate leaves; flowers bisexual, axillary, in umbel-like cyme, with three verticillate bracteoles on the upper half pedicel, deciduous and left articuliform trace; calys 5-partite, petals 5, yellow, marcescent; stamens 15, 3 in cluster between staminodes, the middle one shortest, staminodes 5, liquiform, much longer than stamen; the stamens and staminodes fuse in lower part into staminal column; anther dithocal; ovary sessile, densely tomentose, 2-or 5-locular, loculi 2-ovuled, placenta axile, style simple; capsule subspherical, densely tomentose, surrounded by persistent perianth; seeds ladybud-like with copious endosperm and foliaceous cotyledons 2-lobed in the middle of upper part and epigaeous, the seedling is of Magnolia Type (Ye 1983). III The delimitation of Tiliaoceae and Sterouliaceae In the order Malvales the delimitation between and among families is obscure. The distinction between Tiliaceae and Sterliaceae is so obscure that it is usually difficult to determine a concrete specimen to which family. The two families are discussed in the respects of morphology, anatomy, cytology, embryology and phytochemistry in order to ascertain whether the dolimitation between them can be drawn. Morphologically an obscure distinction between two families presents. Namely, in Sterculiaceae the stamens are usually definite and the filaments usually fuse at the base to form a column, the presence of staminodes arranged in the same whorl with stamens, while in Tiliaceae, stamens are numberous, filaments are free and if staminodes present they are often arranged in the outer whorl. But this does not always function, for there are some mixtures of features in two families. In anatomy, many features of leaf anatomy, seed anatomy, secondary xylem anatomy and so on in the two families are very similar or same or shows obvious transition, it is difficult to distinguish them anatomically. Concerning the cytology, the basic chromosome numbers in Tiliaceae are 7, 9, 8, 10 and 41.47 is for Corchorus, 10 for two genera, 41 for Tilia, the most frequent numbers are 8 and 9. In Sterculiaceae the most frequent stomatic chromoosome numbers are 20 and 40. The basic chromosome numbers are 6, 7, 8, 9, 10, 21, etc. But the number 10 is for most taxa. In the sense of main basic chromosome numbers, two families can be separated but cannot in the sense of whole information of cytology.
页数212
语种中文
文献类型学位论文
条目标识符http://ir.kib.ac.cn/handle/151853/916
专题昆明植物所硕博研究生毕业学位论文
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唐亚. 田麻属和平当树属的系统位置兼论椴树科与梧桐科的界限[D]. 中国科学院昆明植物研究所. 中国科学院昆明植物研究所,1990.
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