To Alphonse de Candolle   4 August [1863]

Down. | Bromley. | Kent. S.E.

Aug. 4th

My dear Sir

Will you permit me to beg you to interest any young Botanist at Geneva to observe one point for me. But the possibility rests on Lythrum Thymifolia or Hyssipifolia growing near you & being still in flower. Vaucher says (Hist. Phys. Tom. 2. p. 371)1 that these two species are dimorphic like Primula. I have examined several dried specimens of L. hyssipifolia & can see no trace of this fact.2 If either species present any difference in length of pistil & stamens, it is most likely that three forms should be presented. Could you get this point looked at for me; & if possible a few flowers of the two or three forms sent me in a letter.3 I may add that in some species of Lythrum two of the forms have the pistil hidden within the calyx.

I have been trying most laborious experiments on L. salicaria, & am extremely anxious to hear about & see if possible, L. thymifolia.—4

I trust to your kindness to forgive me for troubling you & remain, my dear Sir, with sincere respect | Yours very faithfully | Ch. Darwin

Endorsement: ‘4 aout 63’

1
Vaucher 1841, 2: 371. There is an annotated copy in the Darwin Library–CUL (see Marginalia 1: 812–5). For CD’s interest in Lythrum, see letter from John Scott, [26 July – 2 August 1863] and n. 6.
2
CD’s observational notes on L. hyssopifolia are in DAR 27: B41a–44 and DAR 109: B92. CD evidently thought that L. hyssopifolia growing wild in Switzerland might differ from the specimens he had examined.
3
Candolle’s reply has not been found.
4
See letter from John Scott, [26 July – 2 August 1863] and n. 6. Lythrum salicaria, L. thymifolia, and L. hyssopifolia are discussed in ‘Three forms of Lythrum salicaria’. CD concluded that L. thymifolia was non-dimorphic; Candolle was not cited (‘Three forms of Lythrum salicaria’, p. 191 (Collected papers 2: 124)).

Manuscript Alterations and Comments

1.5 of L. hyssipifolia] interl
2.2 about] interl

Please cite as “DCP-LETT-4263,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-4263