Several months ago I separately grafted two Tavares Limequat cuttings onto Poncirus Trifoliata. The grafts were successful but they have thorns. The original parent plant has no thorns. If the grafts are clones of the parent, why do they have thorns?

Nicky, juvenile growth is often quite thorny, even if the actual variety is thornless. There isn't much to worry about.
As the grafts mature, the thorns (on new branches) will disappear completely or greatly reduce in their size and number.

Take care,
Igor

Igor,

Thanks!