The adaptations - Orto botanico 'Pellegrini - Ansaldi'

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The adaptations of the plants to the environment

The whitlow-grasses (Draba aspera Bertol.)
The altitude environments are characterised by climatic and soil conditions very difficult for the life of plants, that have at disposal very little soil and are exposed to an intense sunshine and to a constant presence of wind.
The temperatures suffer significant excursions throughout the year and between day and night. The air flows and the weight of the blanket of snow provoke the development of crawling and bearing forms, like those of the whitlow-grasses.

The common houseleek (Sempervivum tectorum L.)
Some of the plants that are found in altitude have pretty small dimensions, little leaves that are positioned in compact rosettes.
The basal rosettes sometimes can be tightly stuck to form bearing or pulvinus; an example is the common houseleek. The leaves are often fleshy to allow the accumulation of water supply, or have a dense hair and trichomes that limit the loss of water through the surface.

The holm oak (Quercus ilex L.)
On the first Apuan mountains exposed to the sea, up to about 300 m of altitude, there are different Mediterranean plant species, evolved in conditions of high temperature and limited water availability, that developed adaptations designed to the reduction of losses of water through the leaf surface; they have typically persistent, small, coriaceous and shiny leaves, and for this reason they are called “sclerophyllus evergreens”. Examples are the holm oak, the common myrtle (Myrtus communis L.) and the strawberry tree (Arbutus unedo L.).

The purple saxifrage (Saxifraga latina Terr.)
On small herbaceous species of little dimensions blossom flowers that sometimes astonish also the most inattentive observers for their aesthetic qualities; their dimensions can be disproportionately big compared to those of the plant, and are very attractive for the few pollinating insects that are found in altitude. An herbaceous species with tiny leaves, the purple saxifrage, you can easily notice when blossom the showy flowers of an intense pink colour.

The rough saxifrage (Saxifraga aspera L. subsp. etrusca (Pignatti) Romagnoli & Foggi)
The arid conditions can be in common among environments that are found in very different geographical conditions. The rocky environments of altitude and also the sandy coastlines are arid.
A factor like the lack of water can lead to the same adaptive strategy in plant species of different environments.
The thorny margins that characterise the leaves of some plants represent a reduction of surface of leaf aimed at the reduction of the transpiration.

The silene lanuginosa (silene lanuginose Bertol.)
Although the abundant rainfall, the altitude environments are arid: the rainwater flows rapidly down and percolate quickly in the depths of the limestone mountains. The snowy precipitation doesn’t reduce the aridity, because the water cannot be used on solid state.
For these reasons, the few plant species that live on the highest altitudes had major adaptations, that represent a defence against the losses of water for the transpiration, like the presence of hair and trichomes, the cuticles and the waxy substances that cover the leaves of some plants, for example the silene lanuginosa, an endemic Apuan entity.
L'ORTO BOTANICO PIETRO PELLEGRINI, Un giardino alpino nel Parco Regionale delle Alpi Apuane
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