This collection holds mostly material collected by Agnes Arber's daughter, Muriel Arber (1913–2004). It includes 31 of Agnes Arber's notebooks about herbals and plant morphology; atavism and the "law of loss," which she independently formulated from botanical evidence; the botany of Johann Wolfgang von Goethe (1749–1832) and Guy de la Brosse (1586–1641); her first herbarium; drawings of plants; "botanical records and cuttings", which includes a letter from her friend and mentor, Ethel Sargant (1863–1918); and drawings and records of botanical work at La-Panne-Sur-Mer, Belgium, and Corfe Mullen, Dorset. Also included are letters mainly to Arber but also including some drafts of her replies and some original letters to Edgar Anderson (1897–1969) and Bernard C. Sharman (1913–?1996). Among the subjects described are early herbals, plant morphology, the "law of loss" and Arber's interest in gathering information on Nehemiah Grew (1641–1712) for an account of his life. In addition to these letters are two to Sargant from Eduard Strasburger (1844–1912) and an unsigned and apparently unfinished note presenting Joseph Hooker's (1817–1911) compliments to Sargant and thanking her for the material she sent him. Besides notebooks and letters, this collection contains seven file boxes of index cards with notes on herbals; page proofs, apparently from the first and second editions, for Arber's Herbals: Their Origin and Evolution (Cambridge, Cambridge University Press, 1912), as well as original photographs for the figures in this book and proofs of the figures for The Gramineae (Cambridge, Cambridge University Press, 1934) and The Natural Philosophy of Plant Form (Cambridge, Cambridge University Press, 1950); reprints of articles by Arber and others; manuscripts of short writings by Arber and other related printed matter and illustrative material.

Added to this collection after the original donation: a series of bound books of articles and writings by Agnes Arber's husband, Edward Alexander Newell Arber (1870–1918); copies of books by Agnes Arber with related notes, articles and correspondence; editions of Agnes Arber's books in multiple languages and additional papers entrusted to the Hunt Institute by Muriel Arber.