When we visited the botanical gardens at Kew last year I was confused by the oak trees — there are many varieties — none was labelled Welsh oak! Wandering through the diverse collection of oak trees I spotted one that looked familiar — one of our trees, it was labelled “Sessile oak”.
Sessile Oak, I read, is also known as Durmast Oak. Cornish Oak and Welsh Oak! Welsh Oak is Quercus patraea — patraea seems to mean “lives in rocky places” (I’d be more convinced if it meant “lives in wet places”!) Durmast makes sense though — dur is strong in French and mast is a spar on a sailing boat.
Don’t be confused with the other native British species, the Common Oak also known as Pedunculate or English Oak. English Oak is Quercus robur — robur means hard timber in Latin.
Welsh oak has acorns that sit directly on the tips of the new shoots (they are sessile i.e. they do not move).
English Oak has acorns on long pedicles so can wave about a bit! They are pedunculate.
The leaves are the opposite — the Welsh have stalks so produce dappled shade.
The English Oak leaves arise directly and densely on the twigs — they make dark shade.
Simple! Except that they hybridize — you get mixtures.
Also the Welsh Oak is said to be taller and more upward stretching.
The English Oak is broader and more spreading.
However, how the tree grows has a lot to do with the density of its planting. A single tree in the middle of a field will stretch out sideways, its fellow in a dense wood with shoot up (slowly) to find the light!