Upon his marriage he moved to Surrey and developed an interest in botany.
In 1881, Hiern moved to Barnstaple in north Devonshire, and lived at the manor house adjacent to the Barnstaple Castle mound. Hiern was quite taken with the country squire role and he assumed many public duties including those of the Lord of the Manor of Stoke Rivers, northeast of Barnstaple, and he was one of the original aldermen of the County of Devon.
Hiern published over 50 works on botanical subjects. Among his chief works was the catalogue of the plants Friedrich Welwitsch had collected in Angola.[3]
The African figwort genus Hiernia[6] was named in his honor, as was the Ixora hiernii (a tropical evergreen shrub), the Pavetta hierniana (an evergreen shrub) and the Coffea canephora var hiernii (a species of coffee plant). Gabon Ebony (Diospyros crassiflora, itself the source of much taxonomic confusion over the years) was also first described by Hiern in 1873.
Notes
^ abcDesmond, Ray, ed. (25 February 1994). "Hiern, William Philip". Dictionary of British and Irish Botanists and Horticulturists Including plant collectors, flower painters and garden designers. CRC Press. p. 340. ISBN9780850668438.