One of the many eucalyptus species brought from other parts of the world, in particular from Tasmania, Eucalyptus risdonii, or Risdon‘s peppermint, is today an endangered species in its place of origin. In Portugal, it can be found for more than 120 years in Quinta de São Francisco, Eixo, Aveiro, a place where it thrives. Discover this tree, one of more than a hundred species of eucalyptus that can be spotted on this property.
At Quinta de São Francisco, in Aveiro, on the border between the Mediterranean and Atlantic climate and in alluvial and sandstone soils, the right conditions are there allowing not only this eucalyptus, but many other species to find their place here and grow and form large trees. More than one hundred of the almost 300 species of trees and shrubs found on the property are precisely eucalyptus trees, filling this estate with a particular and unmistakable aroma. Eucalyptus risdonii are part of the Aromatic section, which includes eucalyptus species whose leaves smell like peppermint and which also includes Eucalyptus amygdalina , Eucalyptustenuiramis, Eucalyptus nitida and Eucalyptus elata.
It is an endemic species of the island of Tasmania (Australia), more specifically from Risdon, the name of the place its scientific name derives from. It occurs under very specific conditions, including on the slopes of small hills, in skeletal (i.e. where the soil is of reduced or compact layers) or clayey soils. Given its decreasing population, caused by the expansion of the urban area, it is considered a Vulnerable species (VU) by the Red List of Threatened Species of the International Union for Conservation of Nature (IUCN). This species is also protected by law in the country, under the Threatened Species Protection Act 1995.
This is a species of great beauty and can be easily identified for its preferred location – the slopes – and its greenish crown, a colour that is there for its young leaves, of blue-grey shade and oval shape at a young age; in adulthood, its leaves are persistent and alternate and their colour is light green, with lanceolate format (that is, spear-shaped) and can grow up to 10 centimetres long and two centimetres wide. The fruits form axillary and solitary inflorescence, with 9 to 15 buds and the flowers are petal-less and have only white stamens. In Portugal, flowering takes place between April and July, attracting assorted native pollinators, a clear proof of how some exotic species can benefit native species. The trunk has a flat bark, deciduous and with irregular strips, and its colours range from light grey to yellow, white and beige.
In Portugal, Eucalyptus risdonii can only be found at Quinta de São Francisco, where it is common, especially to the south-east of the property. Despite being a small species, whose height usually does not exceed eight meters, there are centenarian specimens 27.5 meters in height and about 30 centimetres wide at breast height (DBH).