The dangyuja (Citrus grandis Osbeck) is a variety of pomelo once found in parts of southern and northern Jeju Island, but today mainly limited to the south, in the area surrounding the city of Seogwipo. The tree grows to an average of 6 m high and has 10-13 cm long leaves. The fruit is usually 10-12 cm long, 9-10 cm wide and with a skin about 9mm thick. Individual fruits weigh 300-500 g. In December, the fruit’s color changes to dark yellow as it ripens. Both the fresh fruit and its skin, once dried or boiled, can be consumed. The fruit is sour and the skin slightly bitter. It is propagated through grafting. The fruit is used to prepare dangyuja tea. While the fruit can be bitter or sour, if preserved in sweeteners it can be used to prepare a tea taken to prevent and cure colds. Another preparation of the fruit is into a sort of syrup. The fruit is sliced open at one end and the flesh is dug into and filled with honey and ginger, then re-closed. This is cooked in the ashes of a home fire, and after cooking, people eat the juices, again to combat the common cold. It is also bought locally for the occasions of memorial services to ancestors. It is believed that this fruit variety was brought to Jeju Island from China sometime about 1000 years ago. It is noted as being a variety presented to a king of the Joseon Dynasty and having been present for several hundred years already in a king’s diary dated to 1724. Today, this tree has disappeared from a number of areas where it was once common. There are 24 dangyuja trees over 100 years old protected by the local government, and some are found in the private gardens of houses. In 2011, 200 trees were grafted in the village of Seohung-dong as part of project dedicated to citrus trees. About 2000 kg of fruit are harvested annually. Today, the introduction of other citrus varieties with sweeter fruit and edible flesh, such as Japanese tangerine varieties, means that the local dangyuja fruits have been gradually disappearing. Also decreased is their use in medicinal preparations for the purpose of treating colds.