American botanist Daniel Trembly MacDougal (1865-1958) holding an instrument at the Carnegie Institution of Washington, USA. MacDougal was a leading expert in desert ecology and one of the first to study chlorophyll. Born in Liberty, Indiana, he earned his Master of Science from DePauw University in 1894 and his PhD from Purdue University in 1897. His work in desert plants began in the summers of 1891 and 1892 while collecting specimens for the US Department of Agriculture in Idaho and Arizona. He taught plant physiology at the University of Minnesota from 1893 to 1899, then joined the New York Botanical Garden for seven years. There, he helped establish the Plant Desert Laboratory in Tucson, Arizona, in 1905, serving as its director. In 1909, he founded a coastal botanical laboratory in Carmel, California, gaining recognition for his expertise on Monterey pines. He later directed Botanical Research at the Carnegie Institution in Washington, DC, until his retirement in 1933. Photographed in 1923.