Tree 39: Swiss Stone Pine
The Swiss Stone pine is very slow-growing, with dense foliage, but can live for up to 1000 years. It eventually reaches 25m or more in height with a trunk up to 1.5m in diameter.
It is generally found at altitudes between 1200 and 2300 m, right up to the tree line, where it helps stabilise slopes and prevent soil erosion and avalanches. It is hardy to -50°C and highly tolerant of wind exposure. In the UK, it is a popular ornamental tree used in parks and gardens, with its slow growth making it a sensible choice for smaller landscapes.
A blueish-white line runs the length of the blue-green needles which are 5-9 cm long and arranged in bundles of five. New stems have an orange-brown appearance, but the bark changes as the tree ages, becoming darker with grooved, scaly plates. Cones 4-8cms long start to appear at the ends of branches only after around 50 years. The oily, edible ‘pine nut’ found inside is enjoyed by both humans and birds! The pine nuts have a vestigial wing and are usually spread by spotted nutcrackers. Immature cones are greenish-purple, but mature over a period of two years, becoming brown and eventually falling to the ground in spring. When sliced, the cones can be used to flavour schnapps!
The roots of the Swiss Stone Pine are usually surrounded by white strands of mycorrhizal fungi. The tree feeds sugars to the fungi while the fungi help the tree grow and stay healthy.
Being resistant to most pests and diseases, it is used extensively in hybridisation research to improve the resistance of other pines to disease, especially rusts. The wood of the Swiss Stone Pine is highly prized for furniture and carvings to the interior panelling in Alpine chalets- its aroma is said to aid sleep and relaxation. The slow growth rate of the tree makes it popular with bonsai enthusiasts!