This paper deals with the phylogeny and geographic distribution of the Tribe Astilbeae. Based on the theory of evolution, the general evolutionary trends of the angiospermous characters and outgroup comparison Penthorum, the polarity of the characters of Trib. Astilbeae is determined. The basic chromosome number (x=8) of Penthorum may be considered as the primitive one; x = 7 (8-1 ) of Astilbe and x = 17 (8 + 9) of Astilboides have evidently evolved from Penthorum, whereas x = 15 (7 + 8) of Rodgersia is derived from x =7 and x = 8 through hybridization. The striate reticulate ornamentation of pollen is more advanced than the striate. The Axile placentation is more primitive than the parietal. Carpels,

stamens, petals and sepals have evolved from more to fewer, then to absent in number.Veins of sepals have evolved from uninerviate and pinnate together (or uninerviate) to pinnate and arcuat together, then to arcuat. Leaves have evolved from simple to simple and compound together, then to compound.

     A schema showing phylogenetic tree of Trib. Astilbeae and its outgroup Penthorum is given according to a cladistic analysis using the method of maximal same steps by Xu (1989). In the schema, Rodgersia and Astilbaides is a monophyletic group having a sister group Astilbe, Rodgersia is more advanced than Astilbe; Astilboides is intermediate; while Penthorum is the most primitive and had a common ancestor with its sister group,

     The Trib. Astilbeae consist of three genera. Astilbe, Astilboides and Rodgersia. Based

on the present authort s revision, this tribe comprises 24 species and 13 varieties (excl. typi-

cal ones) in the total. Takhtajan‘s (1986) Eastern Asiatic Region has 32 species and vari-

eties (all of them are endemic) in three genera, ranking the first; the Malesian Region has

three species (endemic) in one genus; the North Amerian Atlantic Region has two species

(endemic) in one genus; the Irano-Turanian Region has only one species, ranking the last.

      In the Eastern Asiatic Region, Japan, Korea and eastern Jilin-Liaoning of China (The

main part of this area is Takhtajan‘s Japanese Korean Provine) has 17 species and varieties

in three genera, which constitute 45.9% of the total in Trib. Astilbeae and include the

groups at different evolutionary stages and 15 endemic species and varieties, of which Astilbe

platyphylla, A. simplicifolia and Rodgersia podophylla may be considered as the primitive

ones. However, the Hengduan Mountains region (west Sichuan and northwest Yunnan)

has 11 species and varieties (10 occur in west Sichuan, 9 in northwest Yunnan) in two gen-

era, which constitute 29.7% of the total number of species and varieties in Trib. Astilbeae

and include 5 endemic species and varieties. From the above mentioned the author suggests

that the centre of origin, present distribution and differentiation of Trib. Astilbeae should

be in Japan, Korea and eastern Jilin-Liaoning, while the Hengduan Mountains region should

be another centre of present distribution.

      The more advanced species, i. e. Astilbe biternata, A. crenatilobata, A. philippinensis,

A. a ‘poensis, A. indica, A. khasiana and Rodgersia nepalensis are found in the area far from

the centre of origin. Thus the Trib. Astilbeae plants may have migrated from Japan, Korea

and eastern Jilin-Liaoning northwards and then southeastwards to southeastern North

America through eastern Siberia and the Bering bridge, southwards to the philippines and

Java through South China, and southwestwards to the Himalayas through the Qinling-Daba

Mountains and the Hengduan Mountains. At present, in eastern Siberia and most parts of

North America there are no plants in the Tribe Astilbeae, Which may be explained by their

extinct ness there during the Quaternary glaciation.

      Both Astilbe and Rodgersia are distributed in the Asian continent and Japan. Japan has

been isolated from the Asian continent since the late Tertiary, so that both Astilbe and

Rodgersia had undoubtedly occurred before Japan was isolated (Early Tertiary). Therefore,

the origin time of the Tribe Astilbeae may be considered as the Early Tertiary or may be

traced back to the Late Cretaceous.

      The pollen morphology of Penthorum sedoides L., Astilbe grandis Stapf ex Wils. and