William Watson (1858-1925) was a British botanist and horticulturist. He was a gardener at the Royal Botanic Gardens, Kew from 1879, Assistant Curator 1886-1901 and Curator 1901-1922. "THE Cactus family is not popular among English horticulturists in these days, scarcely half a dozen species out of about a thousand known being considered good enough to be included among favourite garden plants. Probably five hundred kinds have been, or are, in cultivation in the gardens of the few specialists who take an interest in Cactuses; but these are practically unknown in English horticulture."