Swern (Nysa glaucifolia) is a species of a blue-leafed tree in the genus Nysa. It is found in the Great Lakes region, with the largest portion located around the southern shore of Lake Hyperion. Its fruit, swernfruit, is inedible. Swern tree produces sap which, after being extracted and subjected to a special process, is turned into a sweet juice-like drink called saft. Sometimes alcohol is added to the drink.
The tree was first described in 1325 in the Carl Territories. Swern trees are revered by some Native Bloxmericans as sacred trees. In 1343, President Erik Cassel II died in his sleep while lying under a swern. Initially considered a species of the Fagaceae family. However, in 1877, biologist Ernst Duham established a new monotypic family, Nysaceae, within the Fagales order. Duham's classification remains accepted to this day.
There are four known swern cultivars:
- Bitter swern (N. glaucifolia amararulus) is the oldest known cultivar with the oldest mentions of it dating back to the 15th century. It has the most durable woods from all of the cultivars.
- Brown swern (N. glaucifolia brunneus) is the main swern cultivar. It has browner wood. It is mainly cultivated near Lake Hyperion and Brick Lake.
- Sour swern (N. glaucifolia subacidus) is the least common cultivar
- Ouma swern (N. glaucifolia ouma) is cultivated in southern part of Bloxanada and was named after its first president, Ouma Potts.