American educationalist and naturalist born to missionary parents in Honolulu, Hawaii. Baldwin spent most of his life as a teacher and educational administrator, but also had a keen interest in plants and shells. He specialised in ferns, but is better known in his homeland for establishing the Maui Land & Pineapple company after planting the first pineapple there in 1890 and with his brother, Henry Pierre Baldwin, giving birth to the islands' pineapple industry.

Baldwin sailed round Cape Horn to the mainland United States and entered Yale College in 1853, where he met his wife, Lois Morris. On his return to Hawaii, he was engaged at the Lahaina School for seven years, before managing the Kohala sugar cane plantation (1865-1872). The plantation's success is attributed to his introducing the so-called Lahaina cane. In 1873 he went back to Yale to gain his Master's degree, and was appointed vice principal of Lahainaluna Seminary on his return to Hawaii. From 1877 to 1885, as Inspector-General of Schools, Baldwin established English as the language of education in Hawaii. After some more years working at the seminary, he finally retired from education in 1905.

He was recognised in his lifetime as an authority on Hawaiian ferns and land snails. His chief plant collections were mosses and ferns from Hawaii, collected from 1875 to1878. Paris also holds ferns from remote South Georgia and the South Sandwich Islands (Falklands), attributed to collections by Baldwin in 1892. His father, Dwight Baldwin, was a doctor who played a pivotal role in Hawaiian society, dealing with leprosy and an outbreak of smallpox in his time. He shared his son's botanical inclinations; the doctor was known to undertake horticultural experiments and was an original member of the Royal Hawaiian Agricultural Society, organised in 1850.