sábado, 23 de noviembre de 2013

Flora and vegetation

Aeonium nobile

Ever since the first expeditions by Victorian naturalists, the flora of the Canary Islands has maintained its exotic appeal . The English botanical artist Marianne North was among the first to depict the curious plants she observed on Tenerife, where, in 1875, she devoted several months of her prolific career. The results of her work can be admired at the  Marianne North gallery in Kew Gardens. 

Nowadays, with the advent of global travel, the flora of these islands is perhaps no longer quite so "exotic" as it once was, yet there are still various plants which have a distinctly "African" feel, and others which evoke tropical rainforests...

As a result of the climatic variations due to altitude, the vegetation on La Palma can be classified into five clearly recognnisable zones or belts... plus a handful of other ecological niches not strictly dependent on altitude (watercourses, rock faces, etc.). The five zones in this simplified system are, in ascending order: coastal, thermophile, laurel forest, pine forest, and summit scrub. On the leeward side of the island, isolated from the humid influence of the Trade Winds, the third zone (laurel forest) is absent, and pine forest consequently extends over a larger area.

The first photograph at the head of this post shows one of the most spectacular members of the Aeonium genus, A. nobile, a species exclusive to La Palma. These succulents are generally found at lower elevations, typically clinging to ledges on rock faces, especially on the arid, west side of the island.

Euphorbia mellifera var. canariensis

Laurel forests are particularly rich in endemic plants; one of the most unexpected elements in these subtropical woodlands - since most other spurges on the Canaries are confined to dry, coastal areas - is the Euphorbia species shown above, a plant with a very restricted distribution on La Palma.

La Palma Violet, Viola palmensis
Undisputed star among the island's endemisms, the "La Palma Violet" even features in a well-known local legend. These pretty little plants flower profusely on the summits of the island in May and June.

Summit broom, Genista benehoavensis
Above is another high mountain specialist, endemic to La Palma. In this particular broom species the golden-yellow flowers are tightly clustered, and the foliage is greyish-green in colour, making these bushes easy to differentiate from the more abundant codeso brooms (Adenocarpus viscosus) which dominate the slopes above the treeline.

All five of La Palma's five vegetation zones are still well represented on the island: why not consider a guided walk to identify the key species of each zone?