芍药科植物独特性与起源

Distinctive Characters and Origin of Paeoniaceae

芍药科 Paeoniaceae为单属科 ,其系统发育具有一系列的独特性 ,在被子植物中是独一无二的。绒毡层与花粉母细胞同源 ;珠心细胞与大孢子母细胞同源 ;有众多的大孢子母细胞 ;胚胎发育合子第一次分裂后不产生细胞壁 ,有一个游离核发生阶段 ;具木本习性的牡丹组 ( Sect.Moutan)生殖特性 ,具有根状茎、块根、根出条多种形式的以营养繁殖为主、种子繁殖为辅和专性种子有性生殖的两种类型 ;胚具有上胚轴、下胚轴两段休眠特性 ,打破休眠需按一定的程序和两种不同的温度条件 ;……。与石松亚门某些种类植物具有许多相似性。胚胎发育初期游离核阶段与裸子植物苏铁、银杏基本相同 ;但是 ,游离核原胚细胞化后并不导致胚的直接产生 ,又与苏铁、银杏不同 ,可以解释为与裸子植物平行演化的结果。中国是芍药科植物原始类群起源、演化、分化发展和多样性中心。起源时间可以追溯到古生代的石炭纪 。

Paeoniaceae,a monomarphic family,has distinctive characters for its phylogeny in Angiosperm,such as:both of tapetum and microspore mother cell are homologous,and so are nucellus cell and macrospore mother cell;there are many macrospore mother cells.There is a stage of free nuclei in embryo development,but zygote doesn't produce cell wall in its first division;the Sect.Moutan has two different reproduction ways:obligate seed reproduction and amphitrophic reproduction;the dormitory of its embryo has two stages of epicotyl and hypocotyl;the dormitory could be end if it is treated with two temperature conditions.The family is similar to some species of Lycopdispermae.The free nuclear stage in its earlier embryo development is basically the same as that of Cycads and Ginkgo.But its embryo can't be developed directly from the pro embryo of free nuclei,this is different from that of Cycads and Ginkgo.The authors consider that the family and Gymnosperm might be in parallel evolution. China is one of the centers for species origin,development and species diversity in the world.Based on the formation and separation of pan continent,the origin time of ancient species of Paeoniaceae might be back to the carboniferous of Paleozoic,and was not later than early Mesozoic.The modern species of the family flourished in Jurassic and early Cretaceous.