Helen Jeanne Plummer, one of the five woman micropaleontologists on the Gulf Coast of Texas during the 1920s and early 1930s, was born Helen Jeanne Skewes in Muskegon, Michigan, on May 7, 1891. Her parents moved to Illinois during her childhood, and she attended high school there. In 1913 she graduated Phi Beta Kappa from Northwestern University. Most of the following year she was a fellow there, but she did not complete her education until several years later. She studied at the University of Chicago in 1924 and received the M.A. degree from Northwestern University in 1925. In 1914 she was employed by the Illinois Geological Survey; in 1917 she left that position to work with Roxana Petroleum Company, a subsidiary of Shell Oil Company, in Tulsa, Oklahoma. On May 7, 1918, she married a fellow geologist with Roxana, Frederick Byron Plummer. For the next decade she followed her husband to jobs in several states, in the Netherlands, and in the Dominican Republic, but continued her research. By 1925 she had established a reputation as a consulting paleontologist. In 1928 the couple moved to Austin, where Frederick Plummer accepted a position with the Bureau of Economic Geology at the University of Texas and later established the Petroleum Engineering Department.
In 1930 and 1932 Mrs. Plummer was a special lecturer in micropaleontology at Northwestern University. She did research in a laboratory in her home and later had facilities in Austin at the University of Texas Bureau of Economic Geology, where she became a consulting geologist in 1933. After the death of her husband in 1947, she became a regular staff member of that organization. During the late 1940s she helped Petróleos Mexicanos establish a micropaleontological laboratory.
Following up on the work of Dorothy Ogden Carsey, Helen Plummer became proficient in the study of foraminifera of the Cretaceous and the Paleocene; she described many new species and several new genera. In order to obtain and study samples she served without charge as a consultant for wildcatters and petroleum explorers. She acquired an international reputation through her research and publications and by 1931 was regarded in England as one of the leading American micropaleontologists. She died in Austin on January 11, 1951.