The most common species of tree found on the asari homeworld of Thessia. The Zelana tree grows in most temperate climates, and is named for its transparent, colourless leaves. It is one of the oldest species of tree on the homeworld, with fossilised remnants found dating back several hundred million years, and can grow upwards of 100 meters. The oldest living individual, known as Marrea, is believed to be almost nine thousand years old, and stands in the Inbari Temple, several hundred kilometers to the south of the city of Veris.
The colourlessness of the leaves comes from the lithium ions in the chlorophyll's porphyrin ring, rather than the magnesium ion found in the porphyrin ring of ‘green’ chlorophyll, leaving an observer with the impression that the leaves are made of glass - hence the popularity in tourism and media of the ‘glass forests’ of Thessia.
A genetic mutation occurs in approximately 2% of the species, where smaller leaves are colored pink or red.
The tree blooms in late autumn, extending through the winter and into mid-spring before going dormant during the hottest cycles of the year.
In standard Thessian dialogue, zelana (literally translated as ‘leaf’) can also refer to glass objects or transparency.