1915-16.] BOTANICAL SOCIETY OF EDINBURGH 5 



G. Forrest ; P. helodoxa, Balf. fil. ; TJialictrum sp. ; Coclon- 

 opsis sp. ; Aconitum sp. (twiner); Allium sp. ; Cory- 

 dalis sp. ; Polygonum sp. ; Senecio sp. ; Rumex sp. (7 feet 

 high); and several Umhelliferae were prominent constitu- 

 ents. Several species were identical with those found 

 on the Mekong-Salween divide, on the other side of the 

 Salween. 



A not less characteristic association of the Mekong- 

 Salween divide is the undergrowth of the temperate rain 

 forest, which includes the following : — 



Uinhelliferae (giant herbs, up to 7 feet high) ; Thalictrum 

 Delavayi, Franch. (also up to 7 feet high); Arisaema (3 

 species); Aquilegiasp.; Ribes sip-p. ; Paris sp.; Gonvallaria 

 sp. ; Oligobotrya sp. ; Lilium giganteuTn, Wall, (plants 6 

 to 7 feet high with racemes of 8 to 12 flowers); Boragin- 

 aceae ; Filices (nearly all Polypodiaceae, though in con- 

 siderable variety). 



Liliaceae — including L. giganteum, Wall., and other lilies, 

 several fritillarias, etc. — are not less chai'acteristic of the 

 open forests in the Burmese hinterland above 7000 feet; 

 also Arisaema, ferns, Ribes, and so on. But here many 

 ground orchids and begonias add a more tropical touch, 

 which is enhanced by epiphytic orchids, many climbing- 

 plants, and trees with plank-buttress roots. The very large 

 leaves of the Arisaema spp. and Lilium giganteum are 

 characteristic of these open forests unencumbered with 

 bush undergrowth. 



Comparing now the flora of the Mekong-Salween divide 

 with that of the Mekong- Yangtze divide to the east, we 

 And considerable difl'erences. The Mekong valley itself 

 is very arid, and displays a characteristic association of 

 plants comprising compact low thorny shrubs {Sophora 

 viciifolia, Hance, is the commonest; also a Berberis) and 

 a number of I'ock plants, of which a hedgehog-like 

 Selaginella is the most conspicuous. In some places a fine 

 juniper tree grows on the rocky banks close to the water's 

 edge. Ascending the Mekong-Salween divide, this forma- 

 tion rapidly growing richer (including now a Gupressus ; 

 Daphne calcicola, W. W. Sm. ; Androsace Bulleyana, G. 

 Forrest ; Amphicome arguta, Lindl. ; Didissandra lanugi- 

 nosa, Clarke ; and many more species) presentl}^ passes 



