This paper deals with the floristic phytogeography of Pteridophytes of Dulongjiang, which is situated in the north-west of Yunnan, the west of Hengduan Mountains and the south-east margin of Qingzhang Plateau. 41 families, 102 genera and 275 species (including 5 varieties and forms) of pteridophytes have been recorded from this region up to now. The Polypodiaceae is the largest family among this pteridoflora. The geographical distribution of genera and species have been divided into 16 distribution-types and 13 distribution-types in this paper separately (see table 3 and table 4) . In addition, the similarity coefficients between this pteridoflora and those of other 15 regions are included in the present paper in table 5. Ac-cording to the results of the comparison with the species number per unit area, the analysis of geographical elements of the genera and species and the study on the similarity coefficients etc.

Dulongjiang lies in the northwest of Gongshan county of Yunnan province. The cytological data with respect to the plants distributed in this area had been a complete blank up to now in China. The cytological study about these plants is very important and significant in exploring the origin, and evolution of the flora in Dulongjiang area. Several investigations about the plants there have been carried out. The present paper deals with cyological materials of some monocots from Dulongjiang area for the first time.

This paper deals with the ecological types of pteridophytes of Dulongjiang region. It puts forward that the study on the ecological types should be based on the ecological factors. Therefore, the pteridophytes in Dulongjiang region can be divided into 16 ecological types separately according to the effects of ecological factors, i.e.heliophytes, sciophytes, tolerophytes, megatherm,submegatherm.mesotherm,submesotherm,microtherm,xerophytes,mesophytes, hygrophytes, epiphytes, terraphytes, lithophytes, acidophytes and calnciphytes. Finally, the ecological features of Pteridophytes in this region are: (1) Diversified ecological type; ( 2)Rich in the species of sciophytes, submegatherm and mesophytes; (3)High proportion of the species of epiphytes; (4) Few proportion of the spe-cies of xerophytes and lithophytes.

The genus Remusatia with 4 species is distributed in tropical Africa and Asia. The primitive species R.vivipara occources in an area with the same range as large as that of the genus Remusatia. The origin, development and disjunction of R. vivipara's distribution area is closely related to the genus. The writer of the present paper considers that the genus Remusatia as well as R. vivipara might be originated in Indian peninsula of Gondwanaland. During Oligocene period, Remusatia vivipara pas-sed through Arabian peninsula and furthered into Africa. In other word, they migrated directly into oth-er tropical forest regions.

The genus Rhododendron possesses 58 species,2 subspecies and 8 varieties in Dulongjiang region and these species belong to 6 subgenera. Among them, 1 / 4 are compara-tively more primitive species. There are not many alpine groups and species in this region . which demonstrates that this area is old in geological age and less influenced by the uplift of Qinghai-Xizang Plateau. There are 9 epiphytic species along the river valley which reflects the relic of the tropical ecological enviroment. By the analysis of the endemic species and the distri-bution of other species, this region is regarded as an independent floristic area different to the Hengduan Mountains and Qinghai-Xizang Plateau, but has a close relationship with northeast Burma and its adjacent south-east Xizang. In geological history, they might belong to the same old massif.

After biological and phytogeographical analysing the species of Stachyuraceae, this paper is concluded as followings: 1) The everygreen species Stachyulus cordatulus Merr. with special venation and bisexual flowers is considered as a primitive species in the family; 2) The origin of Stachyuraceae, may be, lies in the region of Dulongjiang area and North Burma, i. e. in West Yunnan-Shanban-Malaya block. It means that Stachyulus species owes its origin to north part of Gandwana land mass before late Paleozoic; 3) Befofre Tertiary period the species of Stachyuraceae was dispersed to different areas of East Asia, so that the family Stachyuraceae has extended into existence since late Cretaceous.

In this paper, the diagnoses of 22 new species and 1 new variety of pteridophytes from Yunnan, 3 new combinations of the genera Osmundastrum Presl. Cyclosorus Link and Phymatopteris Pichi-Serm. , 2 new statuses of the genera Athyriopsis Ching and Polypodiodes Ching are presented, and 14 species of pteridophytes new to China or Yunnan are reported.

Remusatia Schott and Gonatanthus Klotzsch are two closely related genera of Colocasieae-Steudnerinae in Araceae. Both genera characteristically produce branched or unbranched aerial bulbiliferous shoots. All species of them with same basic chromosome num-bers ( 2n= 28) are diploid or triploid. Remusatia is distinguished from the genus Gonatanthus only on its parietal rather than basal placentation. But, the placentiaion is usu-ally various in the same species ( Remusatia ornata, Gonatanthus yunnanensis) . In fact Gonatanthus is so similar to Remusatia that we have to make a combination of them as following.

Species S. cathayensi Merr. et Petrry affinis sed inflorescentiis axillares et in ramulo elaminatis affixa,calycis semiorbiculatis differt.

Habitu L.leucostachyo A.Camus simillimus,sed differt foliis tenuioribus perameneo-chartaceis,nervulis reticulatis gracilioribus distinctis,spicae infructescentibus ad 20 cm longis,cupulis coa1escentibus glande tota inclusis,glande minori lcm alta a basi ad apicem 2/3 partem cum muro cupulae coalescente.

Smilax myrtillus A. DC. var. dulongensis H. Li, var. nov. A typo caule ramisque sine spinis, umbellis 6-10-floris differt. Yunnan: Gongshan Xian, Dulongjiang Area, alt. 1300m, 22 March 1991, Dulongjiang Bot. Expedition 4748 ( Holotypus, KUN), loc. ibid. 1500m, 28 April, 1991, coll. ibid. 6681; coll. ibid. 424, 438, 596, 844, 864, 1282, 1399, 1420, 1541, 3361, 3378, 3592, 3817, 4152 etc. loc. ibid. Nujian Bot. Expedi-tion 790813, 790814, 791155; F. M. Feng 24162; Lianghe Xian .

Species nova R. decursivae (Roxb.) Schott affinis sed foliis subcoriaceis, nervis lateralibus in partitionibus pluris, spadice minore l0 cm longe l.8 cm crasse,sessili rotundato differt.

Species P. forrestii (Takht.) H. Li affinis sed foliis 4, 5, obovatis, rugosis, 10-l5 longis et 6.3-l0 cm latis; ovario 4-5 loculari, staminibus 12 vel l5 differt.

A varietate typica differt foliis latioribus (usquead 5 cm latis) margine lateris latioris l0-dentatis cystolithis 0.05-0.2 mm longis densis praeditis, petiolis usque ad 7 mm longis.