Araucaria angustifolia

The Araucaria angustifolia (also called Paraná pine, missionary pine, Brazilian araucaria, or curí) is a tree species belonging to the family Araucariaceae. Although common names in several languages refer to the species as 'pine', it does not belong to the genus Pinus.

Distribution and habitat

The prehistoric distribution of A. angustifoliain previous geological periods was very different from today. Fossils have been found in northeast Brazil that show that its origin dates back to the beginning of the Jurassic period, 200 million years ago, when the American and African continents were united. Its expansion towards the south is recent, occurring during the late Pleistocene and early Holocene, possibly as a consequence of climate change and migrations through river courses.

Until almost the beginning of the XX century, almost the entire missionary region of La Guayrá (current Brazilian state of Paraná) was covered by araucaria forests, as well as a large part of Santa Catarina, the northern third of the state of Rio Grande do Sul and an important southern strip of the state of São Paulo. To the west, an important part of the Misiones region also had dense araucaria forests.

Currently it is distributed throughout the states in the south and southeast of Brazil and in the Argentine provinces of Misiones and Corrientes, Province of Buenos Aires, Tandil, although there is also a small population in Paraguay, in the department of Alto Paraná and occurs spontaneously in the Sierra de los Ríos, in the northeast of Uruguay.

Although the A. angustifoliaprefers deep, well-drained, slightly acidic soils, it will tolerate almost any type of soil, as long as the drainage is good. It requires a subtropical climate with abundant rainfall, tolerating very high atmospheric humidity and occasional frosts. It is a very popular ornamental tree in subtropical areas, due to the unusual effect of its thick branches, with a reptilian and very symmetrical appearance. It has been artificially introduced, among other places, in southern Bahia, Chile, South Africa, Australia, Kenya, Madagascar, Spain, Portugal and Zimbabwe, with variable behaviour.

General characteristics

The araucaria is an evergreen and relatively long-lived conifer, as its life spans an average of 200 to 300 years, and can reach up to 500 years. Its shape is unmistakable, with a columnar trunk that can reach 50 m in height and 2.5 m in diameter, with a rough and persistent bark 15 cm thick, which supports a radially symmetrical crown shaped like a candelabra or umbrella. When young, the trees have a cone-shaped crown. However, it generally does not reach such imposing dimensions, with a height that varies from 10 to 35 m and a trunk diameter that ranges between 50 and 120 cm in its adult state.

Its morphology varies depending on soil conditions, competition and light availability. The trunk is orthotropic, monopodial and with indefinite rhythmic growth. The branches are arranged in pairs, more or less in the same plane. Its leaves, the needles, are dark green, simple, alternate, spiral, linear to lanceolate, leathery, with very pointed ends, reaching 6 cm long and 1 cm wide. The outer bark has a brownish color, is resistant, rough, wrinkled, detaching in sheets from the upper part of the axis; while the inner bark is resinous, whitish, pinkish in color.

Reproduction and growth

It is a dioecious species, occasionally with monoecious specimens, that is, with both sexes. Its reproduction is done by seeds. Spontaneous vegetative reproduction has not been recorded among Paraná pines, but grafting is possible. Statistically, the number of male and female individuals is equal, that is, the sex ratio does not differ from unity. The male (pollen) cones are oblong, 6 cm long at first, expanding to 10–18 cm long by 15–25 mm wide upon release of pollen. The female cones (seeds), which mature in autumn about 18 months after pollination, are globose, large, 18–25 cm in diameter and contain about 100–150 seeds. It is anemophilous, which means that it depends on the wind for the pollination of its flowers and the subsequent generation of new seeds. Pollination occurs between August and October, when the pollen cones are mature, but female flowering occurs throughout the year.

The seeds need four years to complete maturation. The mature cones fall from the branches between May and August, when they explode and spread the seeds inside for a radius of up to 80 m around the tree. Complementary spread occurs through animals, which feed on them and transport them to other places. The tree gives its first cones at 12 to 15 years of age, when planted, but in the wild it only begins to reproduce at 20 years of age. An average tree produces around 40 cones a year, and can reach up to 200.

The seeds germinate shortly after contact with the soil. Their viability is only six weeks, and if they remain exposed in the ground for too long, they will surely be eaten. Only 0.05% of seeds survive and germinate. As soon as it is born, the shoot sends out a long, taproot, which is why it prefers deep soils. Depth is more important for its growth than the chemical characteristics of the soil, but poor soils also severely harm it, to the point of forcing the plant to remain low in height and assume its senile form before the age of 20.

It grows even in dense forest areas with lots of shade, but prefers moderate shading until the age of two years. In the first years, the araucaria grows little. Right after germination and when it is under a forest, growth is about 7 cm per year, so it can take many years to reach 1 m in height. It then undergoes a growth spurt until age 20, reaching height growth of up to 1 m or more in one year. Diametral growth intensifies when the plant reaches 20-30 years.

Taxonomy

Araucaria angustifolia was described by (Bertol.) Kuntze and published in Revisio Generum Plantarum 3(3): 375. 1898.

Etymology

Araucaria: generic geographical name that refers to its location in Arauco.

angustifolia: Latin epithet meaning "with narrow leaves".

Sinonimia

• Araucaria brasiliana A.Rich.
• Araucaria brasiliana var. gracilis Carrière
• Araucaria brasiliana var. ridolfiana (Pi.Savi) Gordon
• Araucaria brasiliana var. saviana (Parl.) Parl.
• Araucaria brasiliensis Loudon
• Araucaria brasiliensis A. Rich.
• Araucaria brasiliensis var. saviana (Parl.) Parl.
• Araucaria dioica (Vell.) Stellfeld
• Araucaria elegans Carrière
• Araucaria ridolfiana Pi.Savi
• Araucaria saviana Parl.
• Columbea angustifolia Bertol.
• Brazilian Columbea (A.Rich.) Carrière
• Columbea brasiliana var. elegans Carrière
• Columbea brasiliana var. ridolfiana (Pi.Savi) Carrière
• Columbea brasiliensis var. ridolfina (Pi. Savi) Carrière
• Pinus dioica Vell.

Economic and cultural importance

It is a symbol of the Brazilian state of Paraná and its capital the city of Curitiba, as well as of São Carlos in the state of São Paulo and the city of San Pedro in Misiones, Argentina.

Its seeds were important in the diet of the indigenous people, and are still used today in many recipes. They measure 3 to 7 cm long and their diameter ranges between 1.5 and 2.6 cm. The cones or female cones weigh several kilograms and can reach a diameter of about 30 cm, each cone producing between 20 and 120 seeds.

The dried branches of the araucaria tree have a high energy value and can be used for the production of biomass pellets as biofuel.

A worm called koro thrives in fallen trees and is also excellent food for native populations.

This large tree gave one of the alternative names to the missionary region of La Guayrá: La Pinería. On the other hand, the name of the city of Curitiba means 'curís forest' in its indigenous vernacular language.

Conservation

According to one study, it has lost approximately 97% of its habitat due to logging, agriculture and forestry in the last century. People also eat the seeds, which may reduce the spread of the species. Therefore, the International Union for Conservation of Nature classified it as "vulnerable" in 1998 and "critically endangered" in 2008.

Legal protection

The Araucaria angustifolia was declared a natural monument of the province of Misiones in Argentina by law no. 2380 passed on October 24, 1986.