section_path: Ecology/Flora
section_name: Flora
paragraph_text: Flora
  
  Thirteen thousand species of plants have been identified in the Alpine regions. Alpine plants are grouped by habitat and soil type which can be limestone or non-calcareous. The habitats range from meadows, bogs, and woodland (deciduous and coniferous) areas to soil-less scree and moraines, and rock faces and ridges. A natural vegetation limit with altitude is given by the presence of the chief deciduous trees—oak, beech, ash and sycamore maple. These do not reach the same elevation, nor are they often found growing together, but their upper limit corresponds accurately enough to the change from a temperate to a colder climate that is further proved by a change in the presence of wild herbaceous vegetation. This limit usually lies about 1,200 m (3,900 ft) above the sea on the north side of the Alps, but on the southern slopes it often rises to 1,500 m (4,900 ft), sometimes even to 1,700 m (5,600 ft).
  
  Above the forestry, there is often a band of dwarf pine trees (Pinus mugo), which is in turn superseded by Alpenrosen, dwarf shrubs, typically Rhododendron ferrugineum (on acid soils) or Rhododendron hirsutum (on alkaline soils). Although Alpenrose prefers acidic soil, the plants are found throughout the region. Above the tree line is the area defined as "alpine" where in the alpine meadow plants are found that have adapted well to harsh conditions of cold temperatures, aridity, and high altitudes. The alpine area fluctuates greatly because of regional fluctuations in tree lines.
  
  Alpine plants such as the Alpine gentian grow in abundance in areas such as the meadows above the Lauterbrunnental. Gentians are named after the Illyrian king Gentius, and 40 species of the early-spring blooming flower grow in the Alps, in a range of 1,500 to 2,400 m (4,900 to 7,900 ft). Writing about the gentians in Switzerland D. H. Lawrence described them as "darkening the day-time, torch-like with the smoking blueness of Pluto's gloom." Gentians tend to "appear" repeatedly as the spring blooming takes place at progressively later dates, moving from the lower altitude to the higher altitude meadows where the snow melts much later than in the valleys. On the highest rocky ledges, the spring flowers bloom in the summer.
  
  At these higher altitudes, the plants tend to form isolated cushions. In the Alps, several species of flowering plants have been recorded above 4,000 m (13,000 ft), including Ranunculus glacialis, Androsace alpina and Saxifraga biflora. Eritrichium nanum, commonly known as the King of the Alps, is the most elusive of the alpine flowers, growing on rocky ridges at 2,600 to 3,750 m (8,530 to 12,300 ft). Perhaps the best known of the alpine plants is Edelweiss which grows in rocky areas and can be found at altitudes as low as 1,200 m (3,900 ft) and as high as 3,400 m (11,200 ft). The plants that grow at the highest altitudes have adapted to conditions by specialization such as growing in rock screes that give protection from winds.
  
  The extreme and stressful climatic conditions give way to the growth of plant species with secondary metabolites important for medicinal purposes. Origanum vulgare, Prunella vulgaris, Solanum nigrum, and Urtica dioica are some of the more useful medicinal species found in the Alps. Human interference has nearly exterminated the trees in many areas, and, except for the beech forests of the Austrian Alps, forests of deciduous trees are rarely found after the extreme deforestation between the 17th and 19th centuries. The vegetation has changed since the second half of the 20th century, as the high alpine meadows cease to be harvested for hay or used for grazing which eventually might result in a regrowth of the forest. In some areas, the modern practice of building ski runs by mechanical means has destroyed the underlying tundra from which the plant life cannot recover during the non-skiing months, whereas areas that still practice a natural piste type of ski slope building preserve the fragile underlayers.