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Darwin Correspondence Project

To W. E. Darwin   19 [June 1866]1



My dear old W.

very many thanks for Rhamnus, which I have so long wished to see.—2 As a species it seems one step less unisexual than Holly.3 It wd be interesting to know whether the male or Hermaphrodite flowers with rather longer pistil bear any fruit– As stamens are in female far more rudimentary than the pistil is in the male,, at least in the Hermaphrodite, flowers,4 the species probably once existed in state of Thyme, ie, some plants, hermaphrodite & some female, but none as pure males—5

And this is just what I wanted to know— I see no evidence of its having once been dimorphic like Primula.—6

You are the man to do a job thoroughily

Your affect Father | C. Darwin

Do not forget the white Broom.—7

Thanks about N.W. R. Shares. I shall sell. I can get £113 for each share.—8


The date is established by the relationship between this letter and CD’s note, dated 19 June 1866, on Rhamnus cathartica (see n. 4, below).
See letters from W. E. Darwin, [7 May – 11 June 1866] and [18 June 1866] and n. 2.
CD had been interested in the English holly (Ilex aquifolium) as ‘a good case of gradation’ in the development of separate sexes: the plant’s female flowers had fully formed stamens, but no pollen (Correspondence vol. 9, letter to Asa Gray, 17 September [1861]). In Forms of flowers, pp. 297–8, CD placed Ilex aquifolium among plants that either showed a tendency to become dioecious or had apparently become dioecious ‘within a recent period’.
On examining the flowers, CD considered that the third form of Rhamnus cathartica was a male, and not a hermaphrodite. In a note dated 19 June 1866 (DAR 109: A41) CD wrote: ‘W. sent me fl. of Rhamnus Catharticus.... Female fl. with very rudimentary stamens.... Male fl. with rudiment of pistil— … Thirdly a kind of Herm: with quite [interl] small but larger pistil than in male fl. good sized stamens & petals as in male fl. It is apparently male with pistil not so completely aborted’. CD’s further notes on R. cathartica and other Rhamnus species are in DAR 109: A42–4, 50, and DAR 111: A19, B8, 45–6, 48b.
Species of thyme were taken by CD to be representative of a class of plants he later called ‘gyno-dioecious’ (see Correspondence vols. 12 and 13, and Forms of flowers, pp. 298–303).
CD had discovered the phenomenon later called heterostyly in Primula, in which the existence of two flower-forms (long-styled and short-styled) assists cross-pollination (see ‘Dimorphic condition in Primula’ and Forms of flowers, pp. 14–50).
Information on the white broom (Cytisus multiflorus) may have been in the missing portion of the letter from W. E. Darwin, [7 May – 11 June 1866]. William’s notes on C. multiflorus are in DAR 186: 43. On CD’s interest in dichogamy in the common broom, see the letter to George Henslow, [before 19 April 1866], and the letter from W. E. Darwin, 8 May [1866] and n. 2; on his interest in hybrid brooms, see the letter to George Henslow, 15 [June 1866] and n. 5.
The reference to ‘N.W.R.’ shares may have been in the missing portion of the letter from W. E. Darwin, [7 May – 11 June 1866]. From 1846, CD’s Investment book (Down House MS) lists shares of London & North West Railway under Emma Darwin’s trust property. CD’s Investment book (Down House MS) records £72 18s. 9d. for sale of ‘N.W.R.’ shares on 21 June 1866 under the heading ‘Capital paid up’.


Different forms of flowers of Rhamnus.

Letter details

Letter no.
Charles Robert Darwin
William Erasmus Darwin
Sent from
Source of text
DAR 185: 14
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5125,” accessed on 22 March 2019,

Also published in The Correspondence of Charles Darwin, vol. 14