Alexander von Humboldt

Humboldt in Tenerife

     The great explorer and humanist Alexander von Humboldt was born in 1769 into a prominent and wealthy Prussian family. Educated by the finest teachers in Berlin, he soon abandoned his law studies to turn his attention to science, particularly the fields of geology, physical geography, oceanography, meteorology, botany and anthropology.
    He carried out numerous experiments and field studies across all these disciplines: he analysed the currents of the Pacific; he introduced the use of isobars and isotherms in the creation of climate maps; he conducted a study of the Earth’s geography; was the first to establish a link between the drop in average temperature and increasing altitude; discovered that the Earth’s magnetic field decreases from the poles towards the equator; investigated volcanoes, demonstrating that their formation depended on the formation of faults in the ground; and made many other contributions.
    Such was his intelligence, capacity for work, discoveries, proposals for new theories and scientific output that many consider him to be the last universal scientist, heir to the great scholars of Antiquity and the Renaissance.

Commemorative stamp marking the 250th anniversary of the birth of Alexander von Humboldt

     In 1797, he travelled to Paris, where he met Aimé Bonpland, a young doctor and botanist with whom he formed a close friendship and shared a desire to undertake a major scientific expedition across Africa. However, after several failed attempts, they decided to change continent and travel to Central and South America. Thus, with the support of the Spanish authorities, and funded out of his own pocket after inheriting a considerable fortune, on 5 June 1799 they set sail from La Coruña aboard the corvette Pizarro, bound for Havana, carrying on board numerous suitcases and several dozen of the most modern and expensive scientific instruments of the time, such as Berthoud’s chronometer and Ramsden’s sextant.
     Humboldt asked the captain to stop the ship in Tenerife for a few days upon reaching the Canary Islands “…to visit the port of Orotava and climb to the summit of Mount Teide”, the main reason he wished to visit the islands. Thus, on 19 June 1799, Humboldt and his companion Bonpland arrived at the port of Santa Cruz de Tenerife. They had six days to explore everything they had been dreaming of over the past few months. They focused their trip on the northern part of the island, visiting La Laguna, La Orotava and Puerto de la Cruz, observing and recording extensive evidence of the island’s flora and fauna, as well as making interesting notes on the indigenous population and Canarian society at that time.

Portrait of Humboldt and his companion Bonpland at their camp in the Amazon

     On the third day of their stay in Tenerife, Humboldt, his companions and his guides set off from Puerto de la Cruz to follow the so-called Camino de Chasna and climb to the summit of Mount Teide, the main reason for their visit to the Canary Islands. As a true naturalist, he took careful note of the vegetation he encountered as he ascended the island’s highest mountain.
Humboldt was struck by the number of species that were unlike anything he had ever seen before, particularly among the high-mountain flora. The Teide daisy, Argyranthemum tenerifae, the Teide violet, Viola cheiranthifolia, and the imposing red tajinaste, Echium wildpretii, form part of a unique landscape that left a lasting impression on the explorer’s notes and reflections.

     The visual, emotional and scientific impact that the sight of El Teide’s extraordinary flora had on Humboldt is reflected in this excerpt from one of his writings. “We ran about like mad from one place to another, unable to make clear observations because, whenever we picked up a rare specimen, we would put it down as soon as we saw an even more curious one beside it.” And this excitement on the part of both scientists is hardly surprising, given that their visit to Mount Teide coincided with the peak flowering season in that spectacular part of Tenerife.
    Although it seems the weather was not particularly clear that day, in one of his texts he recalls that whilst in “…the summit of Pico de Tenerife, where a horizontal layer of dazzlingly white clouds separates the ash cone from the plateau below, and where, suddenly, thanks to an updraft, the view finally stretches from the very rim of the crater all the way to the vineyards of La Orotava, the orange groves and the lush clusters of banana trees along the coast, pretty little villages on the shore, the sea and all seven islands, amongst which La Palma and Gran Canaria have very high volcanoes, which appeared below us, as if on a geographical map".

The interior of the crater at the summit of Mount Teide, based on Humboldt’s description

     As he climbed the volcanoes, Humboldt realised that the distribution of the various plant species varied according to altitude. He was the first to organise the plants, classifying them according to the different vegetation zones based on the topography of the terrain, microclimates, temperature differences and altitude levels; this description of vegetation integrated into the natural environment is one of his great contributions to modern science, and one which would lay the foundations for what would later become geobotany and biogeography.
    His observations were later set out in his Tableau physique des Iles Canaries. Géographie des Plantes du Pic de Tenerife, one of the most notable works in the history of Canarian botany. In this work, Humboldt identified five vegetation zones on Tenerife, ranging from sea level to the summit of El Teide, which he named the Vine Region, the Laurel Region, the Pine Region, the Broom Region and the Grass Region.

Tableau physique des Iles Canaries. Géographie des Plantes du Pic de Tenerife

     After visiting La Laguna, Humboldt set off for Puerto de la Cruz, passing through the areas of Tacoronte, La Matanza and La Victoria on his way. Upon catching sight of the Orotava Valley, the explorer was struck by its beauty and stopped to take a closer look.
    It may well have been from that very spot that he first caught sight of the famous thousand-year-old dragon tree in the gardens of the Franchy mansion, in the town of La Orotava, which he later had the opportunity to see up close. This dragon tree is the largest on record in history; it is said to have stood 20 metres tall and measured 24 metres in circumference, and that up to a dozen people could gather inside its gigantic hollow trunk, whether to have tea or to attend mass, as it served as a chapel. Unfortunately, all that remains of this colossal tree are a few engravings in which its imposing form can be seen, for after suffering numerous instances of damage and broken branches due to the many storms it endured throughout its long life, a tremendous storm finally brought it down in 1867.
     

El famoso drago de Franchy, en La Orotava

Humboldt’s Vegetation Zones

     “The island of Tenerife, known as ‘Chinerfe’ by the Guanches, currently comprises five distinct plant zones, which can be identified by the names: the Vine Region, the Laurel Region, the Pine Region, the Broom Region and the Grass Region.
These zones are arranged in tiers, one above the other, and cover a vertical height of 1,750 toesas (3,400 m) on the steepest slope of Pico. If the plants in Tenerife do not reach the summit of the volcano, it is not because the perpetual snows and the cold atmosphere impose limits that they cannot overcome; rather, it is the scoria-rich lava of the ‘malpaís’ and the arid, crushed pumice of the Pilón that prevent the plants from spreading as far as the crater’s rim.

     The first area, that of the vineyards, stretches from the coast up to an altitude of 200 or 300 toesas (381–584 m); it is the most densely populated and the only one where the land is carefully cultivated. Among its plant species are eight species of tree-like Euphorbias, Mesembryanthemum – which are found from the Cape of Good Hope to the Peloponnese – Cacalia kleinnia, the dragon tree and other plants which, with their bare, gnarled trunks and succulent, bluish-green leaves, display the distinctive features of African vegetation. In this area, date palms, bananas, sugar cane, Indian fig trees, Colocasia esculenta (taro)—whose root provides the local people with a nutritious starch—olive trees, European fruit trees, vines and cereals are cultivated. Wheat is harvested from late March to early May, and successful trials have been carried out with the cultivation of the Tahitian breadfruit tree, the cinnamon tree from the Moluccas, the Arabian coffee tree and the American cocoa tree. In several parts of the coast, the country exhibits all the characteristics of a tropical landscape, and it is recognised that the palm-tree region extends beyond the boundaries of the tropical zone.

     The second area, that of the laurels, comprises the wooded part of Tenerife: it is also the region of the springs that bubble up amidst evergreen, damp grasslands. Magnificent forests crown the hills flanking the volcano; four species of laurel can be identified there, an oak related to Quercus turneri from the mountains of Tibet, Visnea mocanera, Myrica faya from the Azores, a native olive tree (Olea excelsa) which is the tallest tree in this area, two species of Sideroxylon with foliage of rare beauty, Arbutus callycarpa and other evergreen trees of the myrtle family. The trunks of the laurels are covered with bellflowers and a type of ivy quite different from the European variety (Hedera canariensis), and at their feet there is an innumerable quantity of ferns, of which only three species—two Acrostichum and Ophioglossum lusitanicum—extend down to the level of the vines. The ground, covered everywhere with moss and fine grass, is dotted with the flowers of Campanula aurea, Chrysanthemum pinnatifidum, Mentha canariensis and various shrubby species of Hypericum (Hypericum canariense, Hypericum floribundum and Hypericum glandusolum). Plantations of wild and transplanted chestnut trees form a wide belt around the spring area, which is the greenest and most pleasant of all the vegetated areas.

     The third zone begins at an altitude of 900 toesas (1,750 m), where the last clusters of strawberry trees, Myrica faya and that beautiful heather which the locals call ‘Tejo’ can be found. This zone, 400 toesas wide, is entirely covered by a vast pine forest, interspersed with Broussonet’s Juniperus cedrus. These pines have very long, rather stiff needles, sometimes arranged in pairs, but more often in groups of three within a sheath. Having had no opportunity to examine the cones, we do not know whether this species, which resembles the Scots pine in appearance, is in fact distinct from the eighteen species of pine already known in the Old World. We found the last pines on the slopes of Mount Teide at an altitude of 1,200 toesas (2,335 m) above sea level. In the mountain ranges of New Spain, below the equatorial zone, Mexican pines grow up to 2,000 toesas. Owing to the similarity in structure that exists between the different species of the same genus of plants, each requires a certain temperature and composition of the ambient air for its development. In temperate climates and wherever snow falls, the constant heat of the soil is slightly higher than the average temperature of the atmosphere; it is likely that, at the altitude of El Portillo, the roots of the pines draw their nourishment from soil in which, at a certain depth, the temperature rises to just 9 or 10 degrees.

     The fourth and fifth zones, regions of broom and grasses, lie at altitudes rivalling those of the most inaccessible peaks in the Pyrenees. This is the barren part of the island, where piles of pumice, obsidian and fractured lava hinder vegetation growth. We have already mentioned those flower-filled clusters of alpine broom (Spartium nubigenum) that form oases amidst a vast sea of ash. Two herbaceous plants, Scrophularia glabrata and Viola cheiranthifolia, venture further out into the barren landscape. On grass scorched by the heat of an African sun, Cladonia paschalis covers arid ground, and shepherds light fires there, which spread over considerable distances. Towards the summit of the Peak, Urceolaria and other plants of the lichen family work to break down the volcanic debris. In this way, through the ceaseless action of organic forces, the realm of flora extends across the islands transformed by volcanoes."

El mirador de Humboldt, en el valle de La Orotava

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Piso infracanario

Piso termocanario seco

Piso termocanario húmedo

Piso mesocanario

Piso supracanario

Piso orocanario

Vegetación costera

Vegetación rupícola

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