THE HABITATS OF MONT BLANC

The rocks seem immobile, but it is in their depths that everything begins: each element reacts harmoniously with the others and defines the identity of an entire mountain. That of the Eastern Alps is mostly made up of calcareous rock, rich in calcium carbonate, and it is for this reason that they are inhabited principally by calcicole flora. But plants of this type are also found in the Western Alps, right here in Valle d’Aosta. Like the furry alpenrose, whose leaves are covered in hairs. It is of the same genus as the rusty-leaved alpenrose – whose leaves have rust-colored undersides and which grows in the Western Alps - and they share the common name of alpenrose, because of their bright pink blooms. The difference between them? It’s all in their preferred soil: alkaline and calcareous for the hairy alpenrose, acid for its rusty-leaved cousin.

In this rock garden you will also find Aster alpinus,  Leontopodium alpinum and Saussurea alpina, other species of the Saussurea genus and plants of exceptional beauty, like Silene elisabethae and Minuartia verna, which blankets the ground with tiny white flowers.

The alpine pastures

The alpine pastures begin where the shrubs gradually peter out, leaving open meadows for grazing. The plants here do not grow tall, at least above ground. Graminaceae and ciperaceae conceal very long roots and runners underground, allowing them to survive long periods of drought and grazing by herbivores in the summer. But the pastures are very colorful in the warm months, dappled with golden yellow ranunculi, gentians with their blue corollas, pale blue bluebells and alpine clover (Trifolium alpinum), with its dark pink inflorescences. And then there is the common nigritella, a tiny wild orchid with purple flowers that emit a scent of vanilla. Another very common plant in these parts is the spikenard (Nardus stricta), which can get by in difficult circumstances and whose tough leaves are not much liked by cattle. In some places, it is able to expand greatly, at the expense of other species.

The wetlands

The flora of the wetlands flourishes wherever there is water – on the surface, underground or in rivulets hidden by the rocks. Here, when the snow melts, rushes and sedges elongate their stems alongside dwarf willows, with their dark, thick, rounded leaves. Towards summer’s end you might see what appear to be soft colored cushions resting on some of the rocks. They are flowers: the yellow ones are fall saxifrage and the fuchsia ones are Fleicher’s carnation. Orchids, cotton grass and chives instead grow in the boggy meadows, and along the banks of the torrents. Around the ponds there are two species of cotton grass with plain flowers, which become white puffballs when they mature: Eriophorum angustifolium and Eriophorum scheuchzeri.

The alder grove

If we move to the north face of the mountain, we can admire a climber of exceptional strength, a true pioneer. It grows readily on rocky ground, making it richer in nutrients. Its dense, bushy branches, curved and elastic (prostrate, in botanical jargon), cover the slopes and, during rockslides or avalanches, slow the impetus of the falling material and bear its weight.

This plant is the green alder (Alnus viridis), which can reach up to three meters in height. On its roots live nitrogen-fixing bacteria that make the soil rich in nutritive substances, as if it were fertilized. Thanks to this nourishing soil, the megaphorbias, well-developed plants with large leaves, also make this habitat their home.

The scree slope

Just below the permanent snowline there is the scree slope, steep and littered with detritus and sand. It would seem an inhospitable place, but even here we find little, obdurate patches of green. This is the home of the pioneer plants, so called because they are always the first to colonize habitats where food is scarce. It’s a constant battle with the soil, and each plant has its weapons: long roots to anchor themselves well or microscopic adherent leaves to cling to the rocks. One of the plants that has grown long roots is the cushion silene, also known as cushion pink: it looks much like a moss, but it blooms with an abundance of tiny pink flowers.

The rhododendron – bilberry

The rhododendron – bilberry habitat lies just above the coniferous forests. As the larches and firs gradually thin out, more and more space is taken up by the so-called ‘twisted bushes’. Twisted because instead of growing vertically, their trunks extend parallel to the ground, bending under the weight of the winter snows. There are many of them in the Gardens: junipers, rhododendrons and bilberries. Everyone knows the bilberries, and the plant is easily recognizable, especially when bearing its famous sweet berries. Less well known are the dwarf juniper, a bush that grows against large boulders, taking advantage of the heat they retain, and the rhododendron, a shrub that grows on soil rich in humus and prefers northern exposures. The Rhododendron (Rhododendron ferrugineum) is one of the ‘twisted bushes’: it blooms in early summer, when its lovely intense pink-fuchsia flowers color the slopes of our mountains. In bloom, the plant resembles an azalea, and in fact, both plants belong to the family of the Ericaceae.