The letter for the seventh Lunar month is D and the corresponding tree from the Ogham alphabet is the English Oak..... The mighty King of the Forest. Symbolising a door and connected to Thor and thunder.
Oak(Quercus ) The generic name is the Latin word for tree. The largest and longest lived of Britain's native trees. Oaks were often planted to mark the boundaries of Parishes.
Top left corner of the right hand page shows how the letter would be carved on a stick.
Below are two more pages from the Ogham Sketch Book by Karen Cater all about famous oak trees of the past.
The fully grown oak I have here at home is a Turkey Oak which is a bit different but just down the road are many proper English Oaks, this beauty is closest to home and they line the lanes all around our little hamlet. Probably as old as the oldest houses and farms.
I had good intentions of finding more information about Oaks but ran out of time. And I've failed on replying to comments this week or commenting elsewhere - sorry - it's been a busier week than the last 14.