There are about 600 species of Oak trees and shrubs belonging to the genus Quercus. The common oak (Quercus robur), sometimes known as the English oak, is very widespread in Britain, and is said to have been the predominant tree of Europe since prehistoric times.
The oak (like the ash and the hawthorn) has played an important part in Celtic mythology, legend and folklore. It is believed to have magical properties and has been considered one of the gateways to the Otherworld. It can be seen that the ‘oak’ features prominently in the englyn that Gwydion sings to Lleu during the period he is transformed into an eagle.
Broom is the name given to a large number of shrubs which belong mainly to the genera Chamaecytisus, Cytisus and Genista. One of the most well-known is the common broom (Cytisus scoparius) which is widespread throughout northern Europe. The majority of broom species have yellow flowers.
Meadowsweet (Filipendula ulmaria) is a perennial herb which is widespread throughout Europe and Western Asia. It grows traditionally in damp meadows which explains its alternative name, queen of the meadow, and its Welsh equivalent, brenhines y weirglodd. It is believed by some to have been one of the sacred herbs of the Iron Age priestly order known as druids.