Rowan, Ogham name Luis, rules 21st January to 17th February and its element is that of Fire. It is also known as "Quicken Tree" ~ the tree of life, in Norse it is called "Runa" meaning rune or charm for magic.
Imbolc, in the Celtic seasonal calendar marked the beginning of the lambing season and signaled the beginning of Spring and the stirrings of new life. It is Feile Brighde, the 'quickening of the year'. The original word Imbolg means 'in the belly', and therein you have the underlying energy. All is pregnant and expectant