Araucaria araucana

The *Araucaria araucana* is a remarkable evergreen conifer. It is known by many names, including the pehuen, the Chile pine, and the monkey-puzzle. This tree is the national tree of Chile and the Argentine province of Neuquén. It belongs to the Araucariaceae family. It is considered the hardiest species within the *Araucaria* genus. Today, the tree faces significant challenges. The IUCN changed its conservation status to Endangered in 2013. This change occurred because logging, forest fires, and grazing have caused populations to shrink.

The tree has a very specific way of growing and changing over time. Juvenile trees start with a broadly pyramidal or conical shape. As they reach maturity, they develop a distinctive umbrella form. The leaves are thick, tough, and scale-like. They are triangular and broad at the base with sharp edges and tips. These leaves are incredibly long-lived. They can remain attached and stay alive for up to 24 years. This allows them to cover almost all parts of the tree, except for the oldest branches.

Reproduction in *Araucaria araucana* involves a process called being dioecious. This means that male and female cones grow on separate individual trees. The male cones are oblong and shaped like a cucumber. These cones expand during pollen release. The tree relies on wind pollination to move pollen from male to female trees. The female cones are globose, which means they are large and round. These cones mature in the autumn, about 18 months after pollination. Each large cone can hold approximately 200 seeds. When the cones reach maturity, they disintegrate to release long, nut-like seeds.

Nature provides several ways for these seeds to spread and grow. The species is a masting species, meaning it produces large amounts of seeds at certain intervals. This strategy helps ensure some seeds survive by overwhelming predators. Rodents are vital for this process. The long-haired grass mouse, *Abrothrix longipilis*, is the most important animal for seed dispersal. Unlike other animals, this mouse buries the seeds whole in locations good for germination. The austral parakeet also helps disperse seeds. This is especially important after large ecological disturbances like volcanic activity. Parakeets can carry seeds far away from affected territories.

The history of how we name and study this tree is quite long. The Spaniard Francisco Dendariarena first mentioned the tree in 1780. In 1782, J.I. Molina named it *Pinus araucana*. Later, in 1873, the scientist Koch published the name *Araucaria araucana*. This name comes from the native Araucanians. The Pehuenches people live in the Andes and owe their name to their diet. They call the tree "pewen," which means *Araucaria*. The English name "monkey-puzzle" comes from a 19th-century observation. A man named Charles Austin saw a specimen in a garden. He remarked that it would puzzle a monkey to climb it.

This tree is very strong and can survive in tough environments. Its bark can grow up to 15 cm thick. This thick bark may be an adaptation to help the tree survive wildfires. It grows on the lower slopes of the Andes between 500 and 1,800 meters. The tree prefers well-drained, slightly acidic, volcanic soil. It can tolerate temperatures as low as -10°C. Because it is so hardy, it is grown in many places. You can find it in western Europe, North America, New Zealand, and Australia. It can even handle coastal salt spray, though it does not like air pollution.

Humans have many different connections to the *Araucaria araucana*. The seeds, called piñones, are edible and taste like large pine nuts. Indigenous peoples in Argentina and Chile have harvested them for a long time. In the past, the wood was valued for its long, straight trunks. It was even used for railway sleepers in Chile. However, because the trees are now rare, their wood is rarely used. Today, the tree is protected under Appendix I of CITES. This means international trade of the tree is strictly regulated. Scientists continue to study the tree to help it grow in new places. For example, researchers have planted them in old clay pits in England to study regreening.