The Elm Tree is mentioned briefly in the How to Train Your Dragon Book series.
Elm trees (Genus Ulmus) are trees occurring mainly in the Northern Hemisphere in temperate and mountainous tropical areas, with some species in Indonesia past the equator. They are mainly deciduous, loosing their leaves for the Winter. The leaves are simply-shaped with a pointed apex, sometimes with serrated edges depending on the species. Their seeds are 'winged' (samara), meaning they have parts that can be blown in the wind for dispersal.
There are many pests, parasites, and diseases of elm trees, including Dutch elm disease, a fungal disease that can kill the tree. Several beetle species can ruin the canopy of elm trees by eating the leaves.
In both real life and in the Book series, Elm is used as a source of wood, prized for its flexibility and resistance to splitting.
In reality, Elm is also a source of some herbal medicines, has been used as animal fodder, and can even be eaten by humans. Boiled elm bark and elm seeds were eaten by Norwegians during the Famine of 1812.