Trifolium

It being St Patrick's Day I went down to the woods to see if any wood sorrel was flowering yet. It's a little early but I was in luck because there was a small clump growing on a mossy rock where,  catching the sun's eye, it was  blooming already.

Wood sorrel, with its delicate, folded, three-lobed leaves is one of the plants to fall under the designation 'shamrock'. The others are wild clover and black medick, all of which bear trifoliate leaves.
Because, in botanical truth, there is no shamrock plant; shamrock is a cultural construct loaded with symbolism, nostalgia and profitable enterprise.

Some say that wood sorrel (Oxalis acetosella  or any other of the global Oxalis family that stand in for it) must have been the real contender because  it was said to have been eaten by the Irish in times past. It's true that wood sorrel is palatable in a tangy, acidic, way but then any plant would have been consumed by those who had no alternative.

The tripartite leaves of wood sorrel (like the clovers) symbolise the Trinity in Christian belief. The great Renaissance painter Fra Angelico is said to have put them in the foreground of his fresco Noli Me Tangere - but I couldn't be sure.