It took some sleuthing to find this Historic Woman (not of Horticulture) of Botany, but I found her!
Marie Clark Taylor (1911-1990) was the first African-American woman to gain a PhD in botany, and the first woman of any race to gain a Ph.D. in science from Fordham University. She later became Head of the Botany Department at Howard University, where an auditorium is named in her honor.
Taylor was born in Sharpsburg, Pennsylvania, on February 16, 1911. After graduating from Dunbar High School in Washington, D.C. with honors in 1929, she earned her B.S.(1933) and M.S. (1935, Botany) at Howard University. A leader in STEM fields, Howard is ranked as the top producer of African-American undergraduates who later earn science and engineering doctoral degrees, according to the National Science Foundation.
In the late 1930s and early 1940s, Taylor taught at Cardozo High School, a historically black high school in Washington D.C. In the middle of that period, she enrolled in the doctoral studies program at Fordham University, where she was a member the Scientific Research Society’s Sigma Xi. In 1941, she became the first woman of any race to receive a scientific doctorate from Fordham when she received her Ph.D. in botany, cum laude. Her research interest was plant photomorphogenesis, or the influence of light on plant growth. For her dissertation, she studied the influence of definite photoperiods upon the growth and development of initiated floral primordia.
During World War II, Taylor served in the Army Red Cross in New Guinea, where she met her husband Richard Taylor. He was serving in the all-black 93rd Airborne Infantry Division. They were married on January 1, 1948 and had one son in 1950.
After the war in 1945, Taylor returned to Washington and joined the Botany Department at Howard University as an assistant professor. In 1947, she succeeded Charles Stewart Parker as Chair of the Botany Department, a position she held until her retirement in 1976. During that time, the department grew, and she was instrumental in the design and construction of a new biology building on the Howard University campus, the botanical greenhouse laboratory on the rooftop of the Ernest E. Just Hall Biology Building.
During her career, Taylor organized a series of summer science institutes for high school teachers in order to introduce them to new methods of teaching science. She encouraged teachers to adopt her innovative methods, such as using real botanical materials and light-microscopes to study living cells. Grants from the National Science Foundation allowed her to grow and develop these summer institutes between the 1950s and 1960s. During the mid-1960s, she was specifically requested by President Lyndon B. Johnson to expand her work nationally and overseas, bringing her teaching style to an international level.
Taylor died on on December 28, 1990 at Walter Reed Army Medical Center in Washington, D.C. Taylor was a “powerhouse who worked tirelessly to improve teacher training in the sciences,” according to her former colleague and civil rights activist Margaret Strickland Collins.
Finding information on historic women can be a challenge. In many instances, their accounts are not recorded, they're not easily searchable, or they're buried in oral histories. This was especially true for Marie Clark Taylor. Some serious detective work may have yielded more results, had I contacted Fordham or Howard Universities. Let's keep digging!
Quinlisk, Katie. "Fordham's First Female Ph.D." The Fordham Ram, 20 Sept. 2017, https://thefordhamram.com/56782/culture/fordhams-first-female-ph-d/ Accessed 11 March 2019. "50 Years of Doctoral Education: 1958-2008" (PDF). Quest (6): 8. Spring 2008, https://web.archive.org/web/20161011004104/https://gs.howard.edu/quest/spring2008/Text.pdf Accessed 6 March 2019.
"28 Days of African-American women in science: Black History Month 2018" MissingSciFaces, 1 Feb. 2018, https://missingscifaces.wordpress.com/ Accessed 20 February 2019.
"Marie Taylor." Revolvy, https://www.revolvy.com/page/Marie-Taylor Accessed 20 February 2019.