His expertise is largely in the study of Verbenaceae, Avicenniaceae, Stilbaceae, Dicrastylidaceae, Symphoremaceae, Nyctanthaceae and Eriocaulaceae.
Harold was born in Watchung, New Jersey, in 1909, and earned a bachelor's degree from Susquehanna University in 1929.
[2] Moldenke's career started at the New York Botanical Garden, a place he maintained a close relationship with (donating many educational materials to its library).
Later, Moldenke took a job in botanical and ecological education as director of the now-named Trailside Nature and Science Center in Mountainside, New Jersey.
In 1967, Moldenke left Trailside and accepted a professorship at the now-named William Paterson College.