[1] William started his education at Ballitore School in County Kildare and by the age of 15 had already established algae as his over-riding interest.

[3] He spent several years in South Africa, and was the author, with German botanist Otto Wilhelm Sonder, of the Flora Capensis (7 vol.

Harvey's discovery in 1831 of the moss Hookeria laetevirens at Killarney, new to Ireland, led to a lifelong friendship with Sir William Jackson Hooker, who was then Regius Professor of Botany at Glasgow University.

In 1835 Harvey went to South Africa aboard the vessel "Carnatic", with his brother Joseph, who had been mistakenly nominated as colonial treasurer by Thomas Spring Rice instead of William.

Back in Cape Town, and now officially treasurer-general, William took up residence at Bishop's Court, rising before dawn every day, collecting in the mountains or sea-shore, and working on the plants at night.

He developed a close friendship with Baron von Ludwig who had started his famous gardens in Cape Town, and dedicated his Genera of South African Plants to him.

Under the patronage of Sir George Grey and with the assistance of a team of collectors and of Otto Wilhelm Sonder, he set about writing a Flora Capensis in English – he lived long enough to see the first three volumes completed and published in Dublin, the third in 1865.

In 1853 he made a three-year voyage, visiting South Africa, Ceylon, Australia, New Zealand, Tonga, Fiji, and Chile.

[5] As a result of the publication of his 1858 book, The genera of South African plants, in which he asked South African readers to send him specimens so that he could begin documenting the flora of the Cape, he began a correspondence with Mary Elizabeth Barber, an amateur naturalist who lived in Cape Colony.

[6] Their ongoing correspondence took place during a time when it was not generally accepted for women to engage in scientific discussion;[7] indeed, in the beginning Barber did not disclose the fact that she was a woman.

[6] Barber became one of Harvey's main suppliers of plants from South Africa and also assisted him in the naming and classification of numerous species.

By the time Harvey set foot in Western Australia he had already established himself as a leading phycologist having published several large works.