Three still to get!
11) A right Welsh one this!
13)A Welsh name and it sounds as if you're fed up!
20) He told them very angrily to leave, I felt sorry - Aah.
A post-prandial thought inspired by vakayu's suggestion - No.11 - Snowdon Lily (Loydia serotina) very rare, only grows in the Snowdon range at high altitudes.