64 
JOURNAL OP THE ROYAL HORTICULTURAL SOCIETY. 
beautiful Tree Heath, a Juniper, and the native Pine formed 
moderately large forests up to 6,000 feet. The fourth and last 
zone was the region of the singular Retama bush, found only 
on the plateau at the foot of the peak, and of a few herbaceous 
plants and grasses found only on the Pealc itself. 
The Canary Islands have furnished facts of the most inter- 
esting character in regard to the distribution and migration of 
plants from the time of Humboldt to the present day. AVebb 
and Berthelot published in 1839 their great work, " Histoire 
Naturelle des lies Canaries," which was long regarded as 
exhaustive. Other workers have, however, explored the islands 
more thoroughly, bringing forth many new facts. 
More recently Mr. W. Botting Hemsley, F.R.S., has reviewed 
the vegetation of the Canary Islands in an able paper in Science 
Progress, ii. pp. 379-398. He bases his conclusions chiefly on 
the writings of Dr. Christ, who has thoroughly studied the 
Canary flora. Dr. Christ distinguishes three regions or zones 
in the islands — namely, the coast, cloud, and uppermost regions. 
The coast region includes the barrancos, or ravines, and the culti- 
vated areas, ranging from the seashore up to about 2,000 feet. 
It is in this region that most of the introduced plants are found. 
The most abundant of the latter are the Cochineal Cactus 
{Opuntia coccmellifera) and the Spiny Cactus (0. Dillcnii). They 
were purposely introduced in connection with the cochineal 
industry, and now that cochineal cultivation has been almost 
abandoned the plants remain as a scourge. The cloud region is 
the zone above cultivation. It is almost constantly enveloped 
in clouds, engendering a green and leafy vegetation. Under 
the shade of trees grow many Ferns, the giant Buttercups 
the Geraniums, the Canary Foxglove, and clumps of the white 
downy-leaved Sideritis. Above this, in Teneriffe only, is the 
singular Alpine region already described. 
There is very little truly herbaceous vegetation in any of the 
Canaries. The plants met with are mainly the weeds of cultiva- 
tion. Of native bulbous plants specially noteworthy there arc 
PancrcUiurii canarieme and two species of lloDiulca. These 
practically exhaust the list. 
