论西藏蒿属植物区系

<正> In Xizang there are 57 species and 6 varieties under the genus Artemisia Linn, which can be divided into 2 subgenera and 6 sections (see P. 82-85).Sect. Absinthium of the genus Artemisia is possibly the most primitive, because the heads are bigger and the flowers on a head are numerous, over 40-100- The inner most flowers of the disk are sterile, the corolla of the outer flower (margine) is similar to the inner ones with 4 (not 2) corolla-teeth. Sometimes there are sterile androecia in the outer flowers. The receptacle is covered with hairs which are developed from the scales in the species of Tribus Heliantheae. Sect. Abrotanum arising from Sect. Absinthium is the intermediate with glabrous receptacle, and the advanced Sect. Artemisia may have arisen from Abrotanum. In this Sect, heads are small and flowers on each head are not very many (< 20). In South-West China (a plant refuge in the Age of Ice of the Quaternary), Sect. Viscidipubes Y. R. Ling may have arisen from Sect. Artemisia or Sect. Abrotanum, and has all the stems, branches, leaves and bracts of the heads clothed with glandular-hairs. With the exception of Subgenus Dracunculus arising from Subgenus Artemisia, Sect. Latilobus Y. R. Ling posseses broader leaf lobes and often occurs in the forest, while Sect. Dracunculus produces narrower leaf lobes and often occurs in the steppe or desert-steppe.Sect. Artemisia in Xizang migrated from the original centre of the genus, which occured possibly in the mountain regions of N. Asia by the middle of Tertiary Period and at the beginning of Quaternary Period. They migrated across C. Asia (East)-Mongolia (West), or through the Sichuan-Yunnan plateau secondary original centre into Xizang and even gave rise to many endemic species of Xizang (for the development system of Artemisia see Fig. 1).The floristical elements of Artemisia in Xizang are so diverse that they are to be summarized as follows: (table l)1. Holartic (subholartic) subkingdom.(1) Tertiary ancient endemic species.2 . Eurasia steppe or semidesert-steppe subkingdom.

ON THE GENUS ARTEMISIA LINN. IN XIZANG

In Xizang there are 57 species and 6 varieties under the genus Artemisia Linn, which can be divided into 2 subgenera and 6 sections (see P. 82-85).Sect. Absinthium of the genus Artemisia is possibly the most primitive, because the heads are bigger and the flowers on a head are numerous, over 40-100- The inner most flowers of the disk are sterile, the corolla of the outer flower (margine) is similar to the inner ones with 4 (not 2) corolla-teeth. Sometimes there are sterile androecia in the outer flowers. The receptacle is covered with hairs which are developed from the scales in the species of Tribus Heliantheae. Sect. Abrotanum arising from Sect. Absinthium is the intermediate with glabrous receptacle, and the advanced Sect. Artemisia may have arisen from Abrotanum. In this Sect, heads are small and flowers on each head are not very many (< 20). In South-West China (a plant refuge in the Age of Ice of the Quaternary), Sect. Viscidipubes Y. R. Ling may have arisen from Sect. Artemisia or Sect. Abrotanum, and has all the stems, branches, leaves and bracts of the heads clothed with glandular-hairs. With the exception of Subgenus Dracunculus arising from Subgenus Artemisia, Sect. Latilobus Y. R. Ling posseses broader leaf lobes and often occurs in the forest, while Sect. Dracunculus produces narrower leaf lobes and often occurs in the steppe or desert-steppe.Sect. Artemisia in Xizang migrated from the original centre of the genus, which occured possibly in the mountain regions of N. Asia by the middle of Tertiary Period and at the beginning of Quaternary Period. They migrated across C. Asia (East)-Mongolia (West), or through the Sichuan-Yunnan plateau secondary original centre into Xizang and even gave rise to many endemic species of Xizang (for the development system of Artemisia see Fig. 1).The floristical elements of Artemisia in Xizang are so diverse that they are to be summarized as follows: (table l)1. Holartic (subholartic) subkingdom.(1) Tertiary ancient endemic species.2 . Eurasia steppe or semidesert-steppe subkingdom.(2) C. Asia (East)-Mongolia (West) steppe or semidesert-steppe region.3 . Qinghai-Xizang plateau subkingdom.(3) Tangut region.