OF SOUTH-EAST SIKKIM. 
835 
Transition to Tibetan Flora. 
It has already been noted that the change in the flora as one proceeds 
northward is a gradual one in the Chola Range. This is in striking 
contrast to the Singalela and the area lying to the north of it. Th(i 
two ridges on either side of the Zemu are so uniformly high and un- 
broken by any southward-tending valley that the aspect of the flora to 
the north (Llonakh) is quite Tibetan. In the Chola the ranges are 
lower and are much divided by lateral valleys so that the change to the 
conditions of Lachung and the Donkia (though these are ultimately 
quite Tibetan) does not appear so abrupt. 
]Xew species from the area. 
The following are the new species collected on the tour : — 
ParoxygrapJiis sikknnensis, Draba cholaenns, Arenaria Balfouriana, 
Potentilla microphylla Don, var. pusilla^ Sarifraga Gageana^ Saxifraga 
pluviarum, Trachydium affine, Leycesteria BeJliana, Senecio liligulatiie, 
Senecio Kingianus, Senecio Lagotis, Senecio Chola, Saussurea nimhorum, 
Saussnrea Laneana, Gentiana pluviarum^ Swertia ramosa, Swertia Bur- 
killiana, Bedicularis sipkonantha Don, var. prostrata Bonati, Pedicularis 
sikkimensis Bonati. Two species of Juncus may prove, to be undes- 
cribed species but they require fuller investigation and comparison with 
ampler material of the genus. 
General Sur^^ey of the Alpine Flora, 
The sub -alpine area, 8 — 10,000 feet above the region of oaks, maples 
and laurels, presented a nearly uniform level of mixed forest from 20 — 40 
feet high, broken only by the tall Abies IF ebbiana. Rhododendrons formed 
a large part of this, especially at the upper limit. The zone above 
10 — 12,OoO feet "consisted chiefly of Pirus, Salix, Viburnum and again a 
majority of Rhododendrons, shrubs rarely exceeding 15 feet in height, 
though in sheltered areas the Abies reappeared. In this zone meadows 
became more prominent but were never extensive. The zone 
above 12,000 feet was partly a kind of 'heath ^ formed by the smaller 
species of BJiododendron and Salix and partly subglacial fell-field with 
a mixture of herbaceous species. In this region annuals were few and 
bulbous and tuberous species only sparingly represented by Codonopsis, 
Mandragora, Cortia, Cochlearia scapiflora, Arisama, Habenaria, Polygo- 
natum, Allium, Fritillaria, Jbloydia. Towards the ridges the density 
of vegetation fell away very rapidly and the chaotic masses of bare 
rocks at the top sheltered only a few hardy forms such as Chysosplenium 
