The date is established by the relationship between this letter and the letter to Fritz Müller, 25 September [1866] (see n. 3, below), and the letter to J. D. Hooker, 25 September [1866] (see n. 2, below). By 25 September CD had received specimens of peony seeds and would not have needed to ask whether they had ‘any thin fleshy coat’ (see n. 3, below).

The description of Erica massoni in Botanical Magazine (9 (1801): facing 356) mentions that the flowers ‘are so extremely viscous that scarcely a winged insect can settle on them and escape with its life’. The leaves are described as ‘hoary’, but there is no mention of the hairs secreting any substance. CD was investigating insectivorous plants at this time, and wanted to compare the glandular hairs of E. massoni with those of Drosera (see letter to J. D. Hooker, 25 September [1866]).

In the letter to Fritz Müller, 25 September [1866], CD mentioned that he received peony seeds from a friend the day after he received Müller’s letter of 2 August 1866 (he wrote to Müller that he had ‘just’ received the August letter). It is likely that Lucy sent the peony seeds. She and her sisters had provided CD with specimens in the past (see Correspondence vol. 10, letter to K. E. S., L. S., and M. S. Wedgwood, 4 [August 1862]). In his Experimental notebook (DAR 157a: 81), CD noted: ‘Lucy W. case at Leith Hill nothing touches or eats the Pæony seeds.’