Joseph Dalton Hooker, was born in Halesworth, Sussex, the second son of the botanist William Jackson Hooker. From the age of seven Hooker attended his father's lectures at Glasgow University. He was educated at Glasgow High school before studying medicine at Glasgow University. He graduated in 1839, entered the Naval Medical Service and joined polar explorer Captain James Clark Ross's Antarctic expedition to the South Magnetic Pole (1839-1843) after receiving a commission as Assistant-Surgeon on HMS Erebus. in 1845 he took up the position of botanist to the Geological Survey of Great Britain. He travelled to India and the Himalaya from 1847-1851. It is from this period that much of the correspondence in the archive belongs. He stayed with Hodgson during this period and would send him letters whilst he was travelling with Archibald Campbell (see BHH/3/1).
Hooker continued to travel including Palestine in 1860, Morocco in 1871 and the west of the United States in 1877.
In 1855 Hooker was appointed Assistant Director of the Royal Botanical Gardens at Kew and he succeeded his father as Director in 1865. He was a Fellow of the Royal Society and served as its President from 1873-1877.
Hooker married Frances Harriet Henslow in 1851 and they had four sons and three daughters, one of whom was named Brian Harvey Hodgson Hooker. Frances died in 1874 and Hooker remarried in 1876, Lady Hyacinth Jardine, and they had two sons. Hooker died at home in Berkshire on 10 December 1911 and was buried alongside his father at St. Anne's Church, Kew.