 Edmondston compiled the first known list of Shetland plants at the age of 11.He discovered several rare plants growing on the serpentine rocks on Unst, including the endemic Shetland Mouse-ear "Cerastium nigrescens", known as Edmondston's Chickweed on the island.In 1845, he produced his "Flora of Shetland", which, despite a few shortcomings, was a considerable achievement given his age and it is still an important reference for Shetland botany.