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Darwin Correspondence Project

From H. C. Watson   23 February [1858]1

Thames Ditton

Feby. 23d

My dear Sir

I do not express an opinion by any means positively;—but my impression is that botanists are more apt to letter & name varieties in large genera than in small ones.

Whether they have done so is a matter of fact, which could be ascertained by patience & time. But this would not show whether they followed external nature, or acted on an internal bias, in the course found to have been adopted, whichever it turned out to be.

Make the distinction between the “lumpers” & “splitters” of species. The former reduce species into vars. & very likely do this more in large than in small genera; the large genera affording more debateable “forms”. The splitters raise varieties into species; thus leaving minor varieties only, to be lettered & named as varieties. I incline to the idea that the same taste or tendency which makes the splitters look out for many species in large genera, also makes them look out for varieties there.

One tendency in botanists seems pretty certain, & may vitiate conclusions deduced from numbers in reference to varieties. Say, that a species has one or two varieties, not up to the mark of sub-species, but still easily described: they are pretty sure to be named & lettered, one or both. Say, that another species has many varieties of like grade or character: they are passed by as too numerous for record.

Take three or four examples from last edit. of Bab. Man.2

Plantago lanceolata— “A very variable plant”— No vars. named, lettered, or descd.

Polygonum aviculare— “Extremely variable”. No vars. specified, except one because given as a species by Contl. bots.

Euphrasia officinalis— “A peculiarly variable plant, perhaps including 2 species”— Only the 2 mentioned by name, &c.

Saxifraga hypnoides— “These vars. are scarcely worth notice.”— They are species in Smith,3 but lumped by Bab.

There is considerable caprice among technical botanists. Under one species or genus they will describe varieties;—while under another, they pass unnoticed equivalent or corresponding varieties. For instance, they will make a variety b glabra or b hirsuta under one species,—while under another equally & similarly varying, the smooth & hairy varieties are mentioned without greek letters or latin names, or not even mentioned at all.—

Very truly | Hewett C. Watson C. Darwin | Esq


Dated on the assumption that CD wrote to Watson about the possible tendency of taxonomists to discern varieties more often in large genera than in small, at the same time that he wrote to Asa Gray and Charles Cardale Babington on the same point (see letters to Asa Gray, 21 February [1858], and to C. C. Babington, 22 February [1858]).
Babington 1856. There is a copy of an earlier edition of this work in the Darwin Library–CUL (Babington 1851).


Babington, Charles Cardale. 1851. Manual of British botany, containing the flowering plants and ferns arranged according to the natural orders. 3d edition. London: John van Voorst.

Babington, Charles Cardale. 1856. Manual of British botany, containing the flowering plants and ferns arranged according to the natural orders. 4th edition. London.

Smith, James Edward. 1824–36. The English flora. 5 vols. in 6. Vol. 5, pt 1 (mosses etc.), by William Jackson Hooker; pt 2 (fungi) by Miles Joseph Berkeley. London: Longman, Hurst, Rees, Orme, Brown, and Green.


Believes that botanists tend to mark more varieties in large than in small genera, but notes that where many varieties of a species exist these varieties may well be passed over, whereas similar varieties of another species which are fewer in number may well be recorded.

Letter details

Letter no.
Hewett Cottrell Watson
Charles Robert Darwin
Sent from
Thames Ditton
Source of text
DAR 98: A21–2
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 2223,” accessed on 19 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 7