Allard, Harry A(rdell) (1880–1963)

US botanist. In 1920, with W W Garner, Allard discovered photoperiodism, a fundamental botanical law that states that the blossoming and fruiting of plants is dependent upon exposure to light. A consummate naturalist, Allard's work on the plants of Virginia and West Virginia resulted in many publications dealing with the songbirds, amphibians, and ‘musical’ insects of the region.

Allard worked for the US Department of Agriculture (1906–46), concentrating his research on the physiology and pathology of tobacco and cotton.