Manchester Memoirs, Vol. Ixii. (1918), No. 8. 15 



curtain. It culminates in the cone of the Peak, which overlooks the 

 desolate region of the Canadas. We have here a rarefied atmos- 

 phere of great clearness, strong insolation by day with rapid fall of 

 temperature after sunset, great atmospheric dryness and a decided 

 winter, more or less snow lying upon the Peak from November till 

 April. Stretches of loose pumice, cones of cinders, scorched cliffs 

 of lava are lit up by a glare of sunshine which renders the shadows 

 correspondingly deep and well-defined. Here, where, reasoning 

 from experience, we might expect a vegetation similar to that of the 

 Alps, we find but the scantiest trace of such a flora. There is in fact 

 no soil to support one. The only plant with a familiar Alpine facies 

 is Arabis albida. The characteristic plant of these high-lying wastes 

 is the broom-like Retdma (Spartocytisus nubigenus), dark, rigid and 

 leafless throughout the winter, clothing itself with silvery-grey foliage 

 in early spring and breaking out into masses of snowy blossom in 

 May. The escobbn and codeso reach the Canadas, but do not dis- 

 pute them with the all-pervading retdma, whose upward range is, 

 moreover, much greater. It dies out upon the Peak rather below 

 the level of 3050 m. (10,000 ft.). The endemic Viola cheiranthi 'folia 

 was found growing in the loose pumice of the Montana Blanca, which 

 flanks the base of the Peak, sending down its long tap-root deep into 

 the substratum. Not a trace of other vegetation bore it company. 

 Silene nocteolens was noted at 2740 m. on the Pico Viejo and 

 Chrysanthemum anethifolium at about the same level. Serratula 

 canariensis also occurs here, but is rare. No phanerogamic plant 

 reaches the shelter-hut, 3262 m. (10,700 ft.), where it was difficult 

 to find even a trace of lichen. At 3570 m. a moss, Grimmia apocarpa, 

 was seen, maintained by condensation of moisture from a volcanic 

 vent. In the crater itself (3760 m., 12912 ft.) a small quantity of 

 a black crustaceous lichen was found with difficulty. A fine Echium 

 (E. auberianum) , with flower spikes four feet high, occurs at the base 

 of the Riscos above Vilaflor. Here, also, ancient specimens of 

 Juniperus cedrus, riven and contorted, are seen clinging to the crags. 

 Elsewhere the demand for its wood has led to the complete eradica- 

 tion of the " cedro." Rosa canina, var. Armidce, was seen at the Pass 

 of Guajara, 2436 m. Two species of Sorbus are said to occur. The 

 " semper vivums " find here their last representative in Greenovia 

 rupifragum and G. aizoon. Mentha sylvestris, var. Teydea, marked 

 the line of a slender runnel of water fed by one of the rare springs of 

 this all but rainless region. Several weeds of the lower levels, Lotus 

 campy locladus, Psoralea bituminosa, Wahlenbergia lobelioides, with a 

 few scattered grasses (Air a, Festuca), growing amongst the retdma, 

 slightly redeem the poverty of this scanty flora which, however, 

 further embraces the following : — Cheiranthus scoparius ; Rhamnus 

 integrifolia ; Polycarpaea aristata ; Pimpinella Buchii ; Pterocephalus 

 lasiospermus ; Senecio palmensis ; Carlina xeranthemoides ; Tolpis 

 Webbii ; Scrophularia glabrata ; Micromeria julianoides ; Plantago 

 Webbii ; Oryzopsis ccerulescens, var. Teneriffce, and a fern, Cheilanthes 

 guanchica. 



