Flora of the Canary Islands. Vegetation zones. Infracanary zone. Flora and vegetation of the Canary Islands

Zone infracanarian

The infracanarian zone, also known as the basal zone or arid mesocanarian zone, is found in all coastal areas of the Canary Islands, but is most prevalent in Lanzarote and Fuerteventura, as these are the flattest and driest islands. It is situated at altitudes of approximately 0–300 metres on the north-facing slopes of the more mountainous islands, and 0–500 metres in dry southern areas, with these limits depending on the degree of exposure to the trade winds.
Precipitation is scarce at this altitude, except on the windward slopes of some islands, such as Tenerife, La Gomera and La Palma. The average is around 100–300 mm per year, with a distribution throughout the year very similar to that of the Mediterranean climate; in very dry areas and during particularly unfavourable periods, there may be no rainfall at all for several years, as is the case in some parts of Lanzarote or Fuerteventura. The average annual temperature is quite high, at around 19–22°C, with mild winters where the coldest month ranges between 11 and 16°C.

These climatic factors, together with the characteristics of the soil and the terrain, determine the type of vegetation in this area, which is characterised by a general absence of tree species and a predominance of herbaceous plants and medium-sized shrubs, which are particularly well-adapted to withstand this harsh climate thanks to the development of various mechanisms for adapting to the environment, such as succulence, reduced foliage, extensive root systems, and spiny stems and leaves, amongst others. On the eastern islands, Lanzarote and Fuerteventura, where the climate is even drier than elsewhere, the vegetation is dominated by herbaceous species that are highly resistant to water scarcity, particularly those of the genera Suaeda and Salsola, such as Salsola divaricata and Suaeda vera, and thorny shrubs such as gorse (Launaea arborescens).

The typical vegetation of the sub-Canarian zone consists of cardonales and tabaibales, characterised by the predominant presence of species from the Euphorbiaceae family: cardones and tabaibas, which together form one of the most characteristic plant communities of the Canary Islands, known as the cardonal-tabaibal.
Cardonals thrive best on rocky slopes and in ravines, and within these, the dominant species—and the one that gives the habitat its name—is the cardón (Euphorbia canariensis), a species with a distinctive appearance that is emblematic of the Canarian flora. It stands out from the rest of the vegetation due to its cactus-like appearance and its large, fleshy, quadrangular stems of an intense green colour; in well-developed specimens, these can reach heights of over 2 m and cover areas of several square metres. Cardonales can be regarded as the optimal form of vegetation in the driest coastal areas with the poorest soils on the islands, where specimens often grow on young volcanic soil, having to make use of the cracks in the lava to establish their roots.

Tabaibales are found in a wider variety of locations along the coastline and are characterised by the predominant presence of several species of tabaiba, particularly the sweet tabaiba, (Euphorbia balsamifera ssp. balsamifera), a plant of great biogeographical interest in relation to the origin of the coastal flora of the Canary Islands, as it has very close relatives on the African coasts opposite our islands (Morocco, the Sahara, Mauritania…), as well as in isolated locations in East Africa. The shape and size of the sweet tabaiba vary greatly, particularly depending on the type of soil and the intensity of the prevailing winds where its populations grow; it can appear as specimens almost lying flat on the ground, barely one or two palmos tall, or form large, highly branched shrubs reaching over 2 m in height and taking on more or less globular shapes.

The tabaibales and cardonales are accompanied by a rather distinctive flora comprising a large number of herbaceous plants and small shrubs, including numerous species endemic to the Canary Islands, mainly from the genera Ceropegia, Aeonium, Echium, Sempervivum, Tolpis, Chrysanthemum, etc. Some of these are quite rare, such as the cardoncillos (Ceropegia fusca, Ceropegia dichotoma…), which stand out against the volcanic soil with their whitish colour, the rare cuernúas (Caralluma burchardii), the small tabaibilla (Euphorbia aphylla), or the very spiny Jandía cardón (Euphorbia handiensis).

     Species from the group known as ‘bejeques’ or ‘verodes’ (Aeonium hierrense, Aeonium lancerottense, Aeonium gomerense, Aeonium percarneum, Aeonium ciliatum, Aeonium haworthii, Aeonium davidbramwellii…) are very common, as is the verode (Kleinia neriifolia), the ‘leña buena’ (Neochamaelea pulverulenta), and various types of viper’s bugloss (Echium decaisnei, Echium brevirame, Echium aculealum and Echium leucophaeum) and daisies (Argyranthemum frutescens, Argyranthemum gracile, Argyranthemum haouarytheum…). There are also some plants which, due to their ease of dispersal, germination and low water requirements, become dominant when the natural vegetation is destroyed, such as the balo (Plocama pendula), which, together with the bitter tabaiba (Euphorbia lamarckii), can be abundant both on the unstable, porous substrates of ravines and on the edges of cultivated land in arid areas; and others that specialise in colonising new land, such as the moonwort (Rumex lunaria).
     In the areas closest to the sea, halophilic species can be found, such as sea lettuce (Astydamia latifolia), sea grape (Tetraena fontanesii) and sea everlasting (Limonium pectinatum), which are particularly common in salt marshes. And in the sandy areas of the eastern islands, we find species adapted to this very poor soil, such as the balancón (Traganum moquinii), the lechetrezna (Euphorbia paralias), the centidonia (Polygonum maritimum), the camellera (Heliotropium ramosissimum), the salado (Schizogyne sericea), etc.
    The cardonal-tabaibal also harbours an interesting associated invertebrate fauna, including numerous endemic species, such as the cardón beetle (Lepromoris gibba), whose larvae develop exclusively inside the dead stems of the cardón cacti.
    Furthermore, the large cardón cacti, which can cover areas of several square metres, provide shelter for a significant group of plant species, protecting them from predation by goats.

     In heavily degraded areas of cardonales and tabaibales, it is quite common to find certain species that were introduced for agricultural purposes and have subsequently become naturalised, such as prickly pears (Opuntia maxima, Opuntia dillenii, Opuntia tomentosa) or piteras (Agave americana), and others that have reached the Canary Islands through non-natural means and are now spreading rapidly as invasive species that destroy natural vegetation, such as cat’s tail (Pennisetum setaceum).
    This vegetation layer has suffered a significant degree of destruction at the hands of humans, both through the development of farmland for crops such as bananas and tomatoes, and through the construction of large residential areas intended primarily for tourism.
     Even so, all the islands still have tabaibales in an acceptable state of conservation; indeed, even on the island of Lobos and on La Graciosa there are interesting examples of tabaibas. As for the cardonales, their current distribution is limited to the central and western islands, where very well-preserved examples of this type of vegetation can be found, such as in the Malpaís de Güímar in Tenerife, and some remnants remain in Fuerteventura, such as on Montaña Jandía or Montaña Cardones, but they are absent from Lanzarote and the islets of Lobos and La Graciosa, where it is thought they may have existed in ancient times.

Frutos del cardón

This vegetation layer has suffered a significant degree of destruction at the hands of humans, both through the development of farmland for crops such as bananas and tomatoes, and through the construction of large residential areas intended primarily for tourism.
Even so, all the islands still have tabaibales in an acceptable state of conservation; indeed, on the islands of Lobos and La Graciosa there are some interesting examples of tabaibas. As for the cardonales, their current distribution is limited to the central and western islands, where very well-preserved examples of this type of vegetation can be found, such as in the Malpaís de Güímar on Tenerife, and some remnants remain on Fuerteventura, such as on Montaña Jandía or Montaña Cardones, but they are absent from Lanzarote and the islets of Lobos and La Graciosa, where it is thought they may have existed in ancient times.