Which is why it matters so much that scientists have, indeed, made progress toward identifying the genes that determine how many leaves a four-leaf clover has.

FORBES: The Four-Leaf Clover Gene?

Grass-cutting ants occur in the Chaco region of north Argentina and Paraguay and belong to a subgroup of leaf-cutting ants that specialise in harvesting grass leaves.

BBC: Earth News - Ant's head balancing act revealed by video

For her experiment she studied the inheritance of three traits: a maroon coloured leaf marking, a white V-shaped leaf mark pattern, and the production of hydrogen cyanide in damaged leaves, which is thought to be a defence against predators.

UNESCO: Outstanding Student Award - Realise the Dream

Or so it seemed until the 1950s, when collector Forest Sweet, who had accumulated six stray leaves (a leaf being a single two-sided page), deduced they came from Washington's original.

FORBES: It's Bunk?