Both Scotland and Ireland were heavily wooded and wood sorrel is plentiful in such an environment and if you ask most Scots Gaelic speakers what the shamrock plant is the plant they'd pick is wood sorrel the plant was used for thickening milk to make crowdie.Apart from anything I didn't mean what I wrote to be so definitive as you took it to be there has been and will be debate over the true shamrock for ever but according to Douglas Clyne a noted Gaelic academic and author of "Gaelic names for flowers and plants" the general consensus of most academics in this field is that the shamrock was originally Oxalis acetosella,the wood-sorrel