Watermelon is a fruit-bearing plant mentioned briefly in the How to Train Your Dragon Book series.
Watermelon plants (Genus Citrullus) belong to the Family Cucurbitaceae, making them related to cucumbers, pumpkins, and Squash. They are a vine plant, spreading out along the ground around it. Leaves typically three main lobes, which may be further lobed, depending on the species. Fruits have a thick outer surface, called a rind, while the interior is soft and juicy, with a high water content. Fruit size is comparatively fairly large, with some cultivars of Citrullus lanatus growing as large as 24 inches in diameter. The interior flesh is most commonly known to be red colored, but can also be white, orange, green, or yellow, depending on the species and cultivar.
Watermelons originated in Northeast Africa. Evidence of cultivation and use by humans can be seen by the Egyptians some 4000 years ago. They were later cultivated in India, and then in China. Use spread into Spain in the 900's. It is possible historic Vikings may have encountered watermelon fruit during raids and trading in that area.
In both the Book series and in real life, a watermelon's primary use is as a food item.
Watermelon is served at the Hysteric Tribe's Freya'sday Eve feast in their Great Hall. Hiccup uses one to fight off a Hysteric as he tries to escape from the Great Hall, after stealing the mythical Potato.