The date is established by the relationship between this letter and the letter to J. D. Hooker, 20 March [1877]. The year is confirmed by an early archivist’s note on the letter.
CD refers to a now missing letter he wrote to Daniel Oliver, asking him to hunt through species of Oxalis for cleistogamic flowers or trimorphic species. In his letter of 19 March 1877, Joseph Dalton Hooker wrote that Oliver thought it would be a long job but that he would be glad to aid Francis if CD sent him to Kew. CD replied that it was not worth Francis’s giving up two days (letter to J. D. Hooker, 20 March [1877]).