Harriet A. Walker was a talented and active plant collector who worked as a curatorial assistant at the University of California Herbarium from 1905 until 1927. She died in 1929 at the age of 83, leaving an endowment to the herbarium that has provided significant support for ongoing work.

Born in 1845, she graduated from Mount Holyoke College in Massachusetts, worked twelve years in the herbarium at Wellesley College, and also for a short while at the Gray Herbarium at Harvard. After beginning work at Berkeley, she often collected specimens used by specialists studying various plant groups. She is acknowledged for help in obtaining specimens in prefaces to Laura Frances McDermott's North American Species of Trifolium (1908) and Harvey Monroe Hall and Carlotta Case Hall's Yosemite Flora (1912). Although she also collected further afield, the focus of her collecting was in the Berkeley area. Reading through her collection notebooks, housed in the herbarium archives, one has the impression that she was looking intently at plants all the time, no matter where she was: "Close to Yuba River on dry creek near camp.", "Bolinas Bay... at entrance to Miss Parson's yard", "U. C. Campus at Oxford St. & Allston Way", "On hills rear of Panoramic".

In 1917, Franz Petrak, the Austrian mycologist and monographer of North American Cirsium, described a new species of native thistle and named it for Harriet Walker — Cirsium walkerianum. Walker collected the plant in 1913 in the Thousand Oaks area of Berkeley, near present-day Solano Avenue and Colusa. The species evidently occurred only in and around Berkeley. Petrak expressed his surprise that such a distinctive plant, that he considered not very closely related to any other, had escaped previous notice in such a populous and well-studied area. Current taxonomy includes it in Cirsium quercetorum and further assessment is complicated because no populations of the plant are known to have survived continued development—though it may be difficult to be certain without the careful eye of Harriet Walker on the scene.

Photo: Harriet Walker (right), Berkeley, Cal. [From "Guest Book" of Mr. and Mrs. Samuel B. Parish, Archives of the University and Jepson Herbaria]