THE FLORA OF NORTH-WESTERN YUNNAN. 205 



R. racemosum, &c, are seen at their best when in a soil largely composed 

 of limestone rubble, or a strong, red limy marl. From these points it 

 is natural to conclude that, in some form, lime must be absorbed by 

 the plants, and is therefore necessary for their best development. 



The country between Talifu and Lichiang, though mountainous 

 to a degree, is, nevertheless, a dry area. This is probably caused by 

 the huge bulk of the Tali range acting as a rain-screen in the S.W. 

 The plains are well irrigated by streams which mostly have their 

 origin beneath the mountains, but on the alps long barren stretches 

 of limy grassland are frequent. The region is volcanic, and here 

 again, as at Tengyueh, hot springs abound. The most prolific of the 

 intervening ranges is, that forming the watershed between the valleys 

 of Lang Kong and Hoching. There also Delavay did some collecting, 

 Primula pulchella, P. malvacea, P. vincaeflora, P. bullata, P. rafa, 

 and P. blattariformis being the best of his finds. 



The Sung-kwei pass (fig. 71), one of the least frequented between 

 those two valleys, is of most interest from the extensive Rhododen- 

 dron forests covering many miles of the summit. Nowhere in Yunnan, 

 not even in the more prolific regions of the N.W., is there such a display 

 of bloom during the months of April and May. Forests of tree Rhodo- 

 dendrons, comprising fully a dozen of the finer species, are flanked 

 and backed by moors and meadows which are literally carpeted by 

 masses of dwarf cushion species, bearing flowers of every imaginable 

 shade, from the deepest purple to the palest lilac-blue. 



Though Pere Delavay did not collect on the Lichiang range 

 himself, through collectors employed by him he secured much that 

 was good, but only of those species found at the lower altitudes. It 

 was left to those who followed to skim the cream of the flora nearer 

 the top. 



The plain, descending from the southern base of the range to the 

 col separating the Lichiang from the Hoching valley, is of 8,200 feet 

 altitude, and has, unquestionably, at one time been a lake. The whole 

 formation is purely lacustrine, varying in depth from a few to fully 

 100 feet. The main streams irrigating the lower levels of the valley, 

 and which originate on the mountain flanks, disappear at the base, 

 reappearing towards the centre of the plain. Owing to this, the 

 northern portion is of a most barren nature. The vegetation is 

 mostly xerophytic, consisting chiefly of a stunted form of evergreen 

 spinous-leaved oak. There are also patches of Eriobotrya priono- 

 phylla ; and in the gutters and water channels worn by the summer 

 rains is found a scanty mixed scrub composed of Philadelphus sp., 

 Deutzia sp., Lonicera Mackii, Indigofera pendula, Berberis sp., Wik- 

 stroemia sp., Viburnum sp., Rhamnus sp., Ligustrum ionandrum, 

 Corylus sp., &c., all much stunted. The herbaceous vegetation con- 

 sists, principally, of many species of the least succulent grasses. 

 There are many large stretches covered, to the exclusion of all 

 else, with Spenceria ramalana, a striking plant when growing in 

 masses, a few dwarf Anemones, Gentians, Pedicularis, Campanulas, 

 vol. xu. p 



