论五福花科的分类、进化与分布

ON THE TAXONOMIC SYSTEM,PHYLOGENY AND DISTRIBUTION I ADOXACEAE

根据对五福花科植物的细胞学、花基数变异、花部维管结构及花序形态特征的比较研究，重新提出了五福科的分类系统，并讨论了该科的系统演化及分布区形成。本文将五福花科划分为３属４种。四福花属Ｔｅｔｒａｄｏｘａ具有最低的染色体数２ｎ＝３６，总状花序，顶花侧花同型同数，花部维管结构整齐对称，雄蕊束与花瓣束分离，无疑是代表该科原始祖先性状的属；五福花属Ａｄｏｘａ２种。头状花序，顶花侧花异型异数，五福花Ａ．ｍｏｓｃｈａｔｅｌｌｉｎａ的染色体数为２ｎ＝３６，５４，东方五福花Ａ．ｏｒｉｅｎｔａｌｉｓ的染色体数为２ｎ＝１０８，后者显然在该属中是较进化的；华福花属Ｓｉｎａｄｏｘａ具有复合程度最高的花序和最减化的单花结构，顶花侧花异型异数。此外在根状茎、叶、花萼和子房等方面较前两属有较多特化，因此该属被认为是科内进化水平最高的属。长期以来，五福花科被认为是环北温带分布的１个“单型科”。８０年代初发现在亚洲腹地存在１个纬度最靠南（达Ｎ２７°），面积最大的孤立分布区，而且其东部海拔２３００ｍ处分布着该科最原始的类群四福花属ＴｏｔｒａｄＯｘａ，在该分布区的西部海拔３９００－４８００ｍ的地带分布着核科最进化的类群华福花属Ｓｉｎａｄｏｘａ。因此?

Based on the comprehensive studies of most taxa in Adoxaceae dealing with the evi-dences of cytology,variation analysis of floral parts and basic numbers,the floral vasculature andmorphology of inflorescence,the taxonomic system of Adoxaceae is reinstated and the phylogenyand distribution of Adoxaceae are discussed in detail.Adoxaceae is now divided into 3 genera 4species,of which Tetradoxa has the minimal chromosome numbers 2n=36,racemoseinflorescence,terminal flower and lateral flowers sharing the same type and equal numbers of flo-ral parts(4,4,4,4;4,4,4,4),floral vasculature being regular and symmetrical and the staminalbundles and petally bunles being separated.It can be presumed that Tetradoxa seems to have more primitive characters suggesting an ancestral form of Adoxaceae. The bispecific Adoxa is rela- tively advanced than Tetradoxa,with capitate(actually cymosecapitate)inflorescence,teminal flower and lateral flowers being of different types and unequal numbers of floral parts,A. moschatellina(2,4,4,4; 3,5,5,5),A. orientalis(2,4,4,2;3,6,6,3) between them A. orientalis has the maximal chromosome numbers in the familv 2n=108 is obviously much advanced than A. moschatellina 2n=36,54.The most highly complicated inflorescence of Sinadoxa is a spike with several glomerate interrupted clusters, but each flowers is much reduced. The basic numbers of teiminal and lateral flowers represent as 2,3,3,1, and 3,4,4,1.Besides these it differs widely from Adoxa and Tetradoxa especially in the charecters of rhizome,leaf,calyx and ovary,thus it is con- sidered as the most advanced genus in the family.Adoxaceae has long been known as a monotypic kmilv with cirboreal distribution. During the early time of eighties this century,two new genera nd a largest isolated distribution area of Adoxacaeae were discovered from central Asia to west China. The southern boundary ofthis area were extended south to 27 northernlatitude. Tetradoxa,the most primitive genus located to the east of this area 2300 m above sea level,while Sinadoxa,the most advanced one distributed in the west 3900-4800 m above sea level,In view of these facts,Adoxaceae may be assumed to originate during Tertiary from the subtropical mountains of southeast Asia especially west China. During the stage Adoxa from southern mountainous region had been expelled down to northern flatland and then being gradually adapted to the new enviroment of Taiga forests,thus ending the everenlarged continual distribution,This pattern of distribution area is coincided with that of Spruce forest from southern subalpine to northern tiagaland,and also coincided with the distribution areas of Pyrolaceae and Diapensiaceae.The hnnation of the distribution area pattern of Adoxaceae may be recognized as a prominent exam- ple to illustrate the origination of the North-Temperate(including the Arctic Alpine)distribution area pattern.