Wanda K. Farr (January 9, 1895 – April 16, 1983) was an American botanist known for her discovery of the mechanism by which cellulose is formed in the walls of plant cells.

She began research related to her late husband's work studying the growth of root hairs in plants.

[4][6] Within a few years, Wanda Farr was hired by the U.S. Department of Agriculture as a cotton technologist on the strength of her previous root hair research.

These granules had appeared to microscopists prior to this time to emerge fully formed in the cell's protoplasm.

By contrast, the formation of starch, which is composed of the same elements carbon, hydrogen, and oxygen, could be seen to occur in stages, in structures called plasmids inside the cell protoplasm.