Araucaria araucana (Pehuén or Monkey-puzzle) is the hardiest species in the conifer genus Araucaria. It is native to central Chile and west central Argentina, and is an evergreen tree growing to 40 m tall and 2 m trunk diameter. Because of species' great age it is sometimes described as a living fossil. Araucaria araucana is the national tree of Chile.
The leaves are thick, tough and scale-like, triangular, 3–4 cm long, 1–3 cm broad at the base, and with razor-sharp edges and tip. They persist for 10–15 years or more, so cover most of the tree except for the older branches.
Its native habitat is the lower slopes of the Chilean and Argentinian south-central Andes, typically above 1000 m, in regions with heavy snowfall in winter. Juvenile trees exhibit a broadly pyramidal or conical habit which naturally develops into the distinctive umbrella form of mature specimens as the tree ages. It prefers well drained, slightly acidic, volcanic soil but will tolerate almost any soil type provided drainage is good.
First found in Chile in the 1780s, it was named Pinus araucana by Molina in 1782. In 1789, de Jussieu had erected a new genus called Araucaria based on the species, and in 1797 Pavón published a new description of the species which he called Araucaria imbricata (an invalid name, as it did not use Molina's older species epithet). Finally in 1873, after several further redescriptions, Koch published the combination Araucaria araucana, validating Molina's name in the genus. The name araucana is derived from the native Araucano People who used the nuts (seeds) of the tree in Chile.
The seeds are edible, similar to large pine nuts, and are extensively harvested in Chile. The tree has some potential to be a food crop in other areas in the future, thriving in climates with cool oceanic summers (e.g. western Scotland) where other nut crops do not grow well. A group of six female trees with one male for pollination could yield several thousand seeds per year. Since the cones drop, harvesting is easy. The tree however does not yield seeds until it is around 30-40 years old, which discourages investment in planting orchards (although yields at maturity can be immense); once established, it can live possibly as long as 1,000 years (Gymnosperm Database). Once valued because of its long, straight trunk, its current rarity and vulnerable status mean its wood is now rarely used; it is also sacred to some members of the Mapuche Native American tribe (Lewington & Parker 1999).