A page from the facsimile edition of Burne-Jones' Flower Book, one of 38 watercolour designs reproduced by Henri Piazza et Cie, for the Fine Art Society, London in 1905.
'Key of Spring' is one of many common names for the cowslip (Primula officinalis).
The image seems to have no obvious correlation with any other works produced by Burne-Jones, but upon closer examination, it bears a marked resemblance to figures in earlier works by the artist. The earliest figure appears in the last of the four separate panels that comprise 'The Garland Weavers' (1866), now on permanent loan to Leighton House. The figure in 'Key of Spring' also has the same left arm and profile composition as Fortune in three specific versions of 'Wheel of Fortune' (Hammersmith Public Libraries on permanent loan to Leighton House, 1872-75; Musee d'Orsay, Paris, 1875-83; National Museum of Wales, Cardiff, 1880-83).