Yareta
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Yareta ( Azorella compacta ) |
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Yareta ( Azorella compacta ), also spelled Llareta , is a plant from the umbelliferae family (Apiaceae). The slow-growing desert plant is native to the Andes . There it was and is used, among other things, as fuel, which is why its stocks have declined sharply.
description
Appearance and leaf
The Yareta is a perennial, evergreen and extremely slow-growing plant that forms coral reef-like, hilly, hard cushions with a height of up to 1.5 meters and an area of around 30 square meters, according to early descriptions even up to around 35 square meters. Their roots are strong, woody taproots ; large plants also form small secondary roots on the edge of the cushions.
The woody, winding stem axis , sheathed by old leaves, is prismatic , the lower branches and those of the edge are larger and occasionally run horizontally. They are densely leafy with rosettes, yellow to light green, bare, thick and sessile leaves that are ovate to oblong and round and taper at obtuse angles. They reach a length of 2 to 6 millimeters, a width of 1 to 4 millimeters and occasionally contain resinous droplets.
Flower, fruit and seeds
The inflorescences are sessile or very short inflorescence axes standing clusters of one to five successively opened flowers that are as buds pink to lavender. The calyx consists of four to five membranous leaves, the three to seven flowers are on short flower stalks . The sepals are triangular, pointed and serrated, 0.5 millimeters long and wide. The pale yellow petals are ovate, bluntly tapered and around 1 millimeter long, the stamens around 2 millimeters long, the upright stylus 0.7 to 1.5 millimeters long.
The round, slightly purple-colored split fruits are 4 to 5 millimeters in size and consist of two, sometimes unequal sized, partial fruits, per fruit there are two disc-shaped seeds with a diameter of around 5 millimeters.
Distribution and ecology
Yareta grows mainly in the alpine deserts of the high Andes in southern Peru , Bolivia , northeast Chile and northwest Argentina between 3500 and 5200 m altitude, preferably on temperature-regulating stone piles or boulders, only associated with Lepidophyllum quadrangulare . The plants have an average density of 70 individuals per hectare and cover around 10 to 15% of the area.
They are characterized by extremely slow growth with a radial rate of around 1.4 millimeters per year. Based on such growth, an age of up to 3000 years can be calculated depending on the size of the plants that exist today.
A considerable amount of dead material accumulates inside the plants, which serves as a moisture reservoir and for cooling. This detritus , the growth form, the content of resinous components and the extremely dense growth are all to be seen as an adaptation to the extreme conditions of the high Andes. They reduce water loss and allow the temperature to be regulated. Due to the locations at extreme altitudes and their resinous ingredients, the plants can keep themselves largely free of predators. A large, soft and pink-colored scale louse species that was not determined at the species level was observed on branches close to the ground, as well as small red mites that live on the surface of the plant. Occasionally browsing by goats was also documented.
The plants bloom all year round, but only in certain sections of the plant. Flowering areas as well as vegetative growth can be found especially on the more sunny eastern and northern sides of the plants. It takes around fifteen weeks from flower opening to fruit ripeness. Insects are likely to serve as pollinators, as ants , mosquitoes , small wasps and flies have been observed on the flowers . Falling partial fruits are often driven into crevices by the wind, where they can then germinate. However, less than one percent of all partial fruits are fertile at all.
use
The Yareta has found use in folk medicine in many dosage forms , in the same way as the related Mulinum chillanensis . Preparations from the root were used for pain, asthma, colds, bronchitis and diseases of the kidneys. Treatments of diabetics with infusions accompanied by conventional medicine have shown significant success in lowering blood sugar levels, but further research is still pending.
The use of plants as fuel is more important, but also significantly more problematic from an ecological point of view (similar to Azorella diapensioides ). In the treeless heights, the plants are used by locals as fuel for heating and cooking, and the collected ashes are used as fertilizer; for this they are only dried three to five months after being felled. They owe their popularity as a fuel to their slow and smokeless fire combined with a high calorific value, which at 362,045 joules per kilogram of Yareta is around half as high as that of the same volume of charcoal . The use as fuel by railways and the construction of mines increased in a particularly drastic way. The mine operators subsidized its use, so that by 1958 the employees of the Chuquicamata copper mine alone consumed around 1000 tons of Yareta per month, between 1915 (opening of the mine) and 1958 around half a million tons of the plants were burned. The use carried out in this way is an extreme case of overexploitation , as it was not sustainable due to the slow growth of the plants.
Status and exposure
Decades of pollution have significantly reduced the populations of plants, especially in Chile, and it is also assumed that there are only very few of the particularly large and old individuals left. In Peru, the use of the stocks is now controlled by the government; in Chile, where the species is locally threatened with extinction, it has been placed under strict protection. Although its use as a fuel is now prohibited, there are no energy alternatives to Yareta for the local population, and it is still used as traditional medicine.
Systematics and botanical history
An initial informal description and a fragmentary collection of the Yareta in Bolivia was provided by Joseph Andrews in 1827; Karel Domin described his material eighty years later as Azorella prismatoclada . As early as 1891, however, the Chilean botanist Rudolph Amandus Philippi first described the species as Azorella compacta Phil. Based on a collection by his son Federico from the Chilean-Bolivian border region . In 1899 Karl Reiche added the species to the genus Laretia , but this view did not prevail. Further synonyms are Azorella yareta Hauman and Azorella columnaris H.Wolff . The Yareta is closely related to Azorella corymbosa Pers.
proof
- GE Wickens: Llareta (Azorella compacta, Umbelliferae): A Review . In: Economic Botany. 1995, Vol. 49, No. 2, pp. 207-212
- Carol Pearson Ralph: Observations on Azorella compacta (Umbelliferae), a Tropical Andean Cushion Plant . In: Biotropica. 10: 1, 1978, pp. 62-67
- Karl Reiche: Estudios críticos sobre la Flora de Chile , 1902, Vol. 3, Pt. 1, p. 63, online (PDF, 1.63 MB) (Spanish)
