The Botanical Garden seeks to demonstrate the great similarities between Californian, Chilean, South African and Australian landscapes and those of the Mediterranean basin through a wide-ranging representation of plant species from Mediterranean-type climates.
By either following the main route or exploring the labyrinth of paths, visitors discover the most characteristic plants from the principal Mediterranean plant landscapes. Careful observation enables us to see the similarities and differences between these and, at the same time, to discover certain morphological features that are shared by many plants that have adapted to the Mediterranean-type climate. Any time of year is good to visit the Garden, but its vegetation responds to the conditions laid down by the changing seasons.
In summer, the Garden presents a dry, arid overall image. Only trees with deep roots can find water that allows them to continue their activity. The small bushes and abundant shrubs that are so prevalent in Mediterranean regions shed branches and leaves in order to reduce water loss. Activity only returns after the first rains of autumn. This is when many bulbous plants awaken, annual plants germinate and many bush species sprout new leaves that will enable them to benefit from the winter rains. The vegetation now forms a greener, more vigorous landscape. Due to the landscape winter is usually a time of rest for the aerial parts of plants whilst, underground, their roots grow in readiness for the arrival of rain in spring. This season is when most Mediterranean plants bloom. The Garden now becomes a spectacle of colours that also attracts animals to the plants, pollinating them.
The Australian Mediterranean region, with 700,000 square kilometers, is the second-largest in surface area (this region represents just over 20% of the biome overall). It is formed by two separate sectors, located in the south and southwest of the continent. Some 8,000 species are known, of which 75% are endemic. The climate is Mediterranean with a certain tropical influence due to the proximity of the Oceanic monsoons; this influence means that the summer drought is not as severe as it is in our own region here. Even so, there is a high frequency of forest fires and soils are very poor in nutrients.
Besides the characteristic Mediterranean flora, plants from amongst the temperate flora in the southwest of the continent (the states of Victoria and New South Wales) also grow in the Australian area of the Garden, in addition to its characteristic Mediterranean flora, plants are also cultivated selected from the temperate flora of the southeast of the continent (states of Victoria and New South Wales). Trees and bushes alike are dominated by a large number of species from just a few families, such as Mimosae (Acacia), Myrtaceae (Eucalyptus, Melaleuca, Callistemon) and Proteaceae (Hakea, Banksia, Grevillea).
Also present are other remarkably singular and primitive species of trees, which are characterised by displaying homogeneous behaviour during their growth:
- Xanthorrhoea or grass trees with very narrow, non-fleshy leaves, surprisingly well adapted to fires.
- Casuarinas and conifers from the cypresses group (Callitris genus).
The Mediterranean area of California occupies a narrow coastal strip from Cape Blanco, in the United States, to Punta Baja, in Mexico, its centre roughly corresponding to San Francisco. In an easterly direction, this strip stretches for some 100 or 200 kilometers towards the interior of the continent. Despite its small size (approximately 10% of the total biome), this is the area that presents the greatest continuous stretches of unaltered Mediterranean landscape. It contains some 4,300 known species of which 35% are endemic. In climate terms, there is marked seasonality: 85% of rainfall is concentrated in winter. The summer drought is very severe, although coastal mists partly temper this contrast.
Californian forests present many ecological and evolutionary similarities with those of the Mediterranean basin. Many genera are common to both, such as Pinus, Quercus, Arctostaphylos, Arbutus, Salvia, Artemisia, etc. Wildfires have a similar natural recurrence, the fertility and diversity of soils is comparable, and many species show similar adaptations.
The Mediterranean area par excellence is, of course, the Mediterranean basin, which is formed by the lands that surround the Mediterranean Sea. This area stretches across European, Asian and African territory, occupying a total area of 2,300,000 square kilometers. It contains some 25,000 known species, of which 50% are endemic. Mediterranean flora presents numerous solutions to adapt to the ecological factors that have influenced its evolution: tough, persistent leaves to withstand the summer drought; thorns, prickles, and toxic substances to defend against herbivores; low plants in the form of cushions or bushes that lose their leaves in the summer to reduce transpiration and so on.
In the Garden, the flora of the vast Mediterranean basin is distributed into four bio-geographic sub-regions: Eastern Mediterranean (between Italy and the Caucasus); Western Mediterranean (the Iberian Peninsula and the Balearic and Tyrrhenian Islands); North Africa (from Morocco to Tunisia); and the Canary Islands.
The South African Mediterranean area is the smallest of all, representing just 3% of the biome. It contains some 8,550 known species of which 68% are endemic. Rainfall, never abundant, is concentrated in the cold Seaton. However, the summer influence of tropical monsoons means that there is no completely dry season. The diversity of soils, the climate and the relief, together with geographic isolation and the frequent incidence of fires, have generated very high diversity, with the result that the proportion of endemic and rare species is, together with that of south-western Australia, the highest in all the Mediterranean areas and one of the richest in the world.
The Chilean Mediterranean area is formed by a narrow coastal strip, some 100 kilometers in length, which corresponds approximately to Central Chile. Its surface area (some 140,000 square kilometers) represents less than 5% of the total biome. Climatically, this is a rather cool region owing to marked oceanic influence, with abundant incidence of coastal mists. Some 2,400 species are known, of which 23% are endemic. An important ecological characteristic of this area is the historic absence of fires, as well as the marked presence of herbivores, especially camelids (llamas and guanacos). As a result, the Chilean Mediterranean area is abundant in spiny bushes, while plants adapted to fire are not found.
In the Garden, subtropical habitats are represented that are typical of the desert and sub-desert regions in the north of the country. The Chilean Mediterranean has a large variety of sclerophyll landscapes (plants with hard, rigid leaves), with woodland and shrubland formations that range from the sclerophyll forest to the coastal “matorral” and including the ‘espinal’ or spiny hillside shrubland. Many Chilean plants have names of Iberian plants because the first colonists compared them with the plants they knew from home. Plants such as the ‘algarrobo’ (Prosopis chilensis), the ‘espino’ (Acacia caven), the ‘belloto’ (Beilschmiedia sp.), the ‘murta’ (Ugni molinae) and the ‘arrayán’ (Myrceugenia obtusa) give the Chilean phyto-scenarios their own distinctive air. Worthy of highlight is the exotic nature of the Cactaceae (genera Trichocereus and Echinopsis) and of the Bromeliaceae (genera Puya and Fascicularia) of the ‘espina’, and the singular nature of the Escalloniaceae (Escallonia sp.).