The archive comprises around 335 letters sent to George Maw, along with four sent to his father, John Hornby Maw. The majority of the correspondence is botanical or geological in nature, and reflects George Maw's passion and renown in these fields. His correspondents include Charles Darwin and other fellow scientists at the Royal Society (Michael Foster, J.D. Hooker, Thomas Henry Huxley and Henry Baker Tristram), fellow horticulturalists (Gertrude Jekyll, Dorothy Nevill, Horace P. White, Mary L. Wynne, and the son of John Dillwyn Llewellyn with regard to his father's collection and garden at Penllergare, Swansea), fellow botanists (Giles Munby, William D'Arcy Godolphin Osborne and Anthony Hurt Wolley-Dod), fellow artists (Charles West Cope and John Ruskin), and those who collected botanical specimens for Maw, particularly abroad (W.L. Adamthwaite, Joseph Cranage, Robert Drummond Hay, Austen Henry Layard, Mariano de la Paz Graells, Max Leichtlin and Charles William Louis Merlin).
The archive includes 15 letters from Charles Darwin, written between 1861 and 1880, which show that Darwin invited Maw's observations on his theories, and incorporated some of them into his work. Around 200 letters in the archive are from Joseph Dalton Hooker, director at the Royal Gardens, Kew, who wrote about the development of the Royal Gardens, contemporary practices there, and anxieties and problems around the management of the gardens. Hooker wrote candidly to Maw of his frustration and despondency at the time of the 'Ayrton controversy' in the early 1870s. Maw and Hooker developed terracotta plant labels for use at Kew Gardens and many letters reflect the refinement of these. The letters reveal the two men's passion for plants, especially the genus Crocus, and a good number detail the equipment Hooker and Maw were sourcing in preparation for their plant collecting expedition to Morocco in 1871. Hooker's letters include references to his private life, family and friends. Ruskin's letters to Maw include the lines, 'The little pet you sent today is put into water very tenderly', and 'The gardener nursed me through my illness as carefully as if I had been a crocus'. Maw sent gifts of plants to Gertrude Jekyll after they met in 1880, and in 1886 Jekyll wrote that she wished that they lived 'within neighbourly distance'. Across the correspondence as a whole, other topics include plant collecting, gifts of plants, bulbs and porcelain, geological finds, and Maw's work on 'A Monograph of the Genus Crocus', published in 1886.
Photocopies of 13 letters from George Maw to Charles Darwin were found with the archive and catalogued as an associated archive (MAW/Z1).