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Darwin Correspondence Project

From H. C. Watson   26 November 1856

Thames Ditton

Novr. 26. 1856

My dear Sir

It is some score of years since I gathered the Subularia, & once only. The specimens are in advanced bud, but not quite to the flowering (impregnating) point. From recollection, too distant & unclear for reliance, the plants were under water, & where they would still be under water when (or, possibly, if) the pollen would be perfected.— This does not meet your question.1 There is discrepancy or contradiction in English writers, Smith, Hooker, Lightfoot.2 But the following passage seems simple & clear on the point, & is from an author in general very reliable:—

“S. aquatica”— “In piscinis sub aqua, et, aqua æstate exsiccata, ad margines piscinarum”—

“Sub aqua clandestine floret; extra aquam flores parvi albi explicantur”—

Koch Synopsis Floræ Germanicæ et Helveticæ, ed. 2 p. 73.3

Of Limosella aquatica I have probably seen thousands of plants in flower. It grows in hollows, & sides of ponds liable to fluctuations in the level of the water,—so that it is frequently left uncovered, & certainly flowers out of water. From the situations in which it grows, a day or two of heavy rain in autumn will submerge it while in flower, & I have seen it apparently flowering under water, under such circumstances. I do not recall ever having seen it in flower under water in places where it must have remained under water during the growth of its buds up to the actual flowering. In the wet summer of 1843 I found two plants of it, one nearly in flower, the other in flower & past flower, on a spot where they never had been under water, but must have grown on the ground, out of water,—very proby. carried to the spot in a gardener’s watering-can, either as seeds or as very young plants, from a pond some 60 yards distant; a public road, & thick hedge intervening.—

This is a longer answer than you required, I hope not too long. Dr. Dickie, Prof. of Boty. in Queen’s College, Belfast, could perhaps answer your question as to the Subularia.4 The specimens in my herbarium, the appearance of which most suggests the idea of flowering out of water, are from him, gathered in his former vicinity of Aberdeen.—

Sincerely Yours | Hewett C. Watson


See letter from C. C. Babington, 22 November 1856, n. 1.
J. E. Smith 1824–36, W. J. Hooker 1830b, and Lightfoot 1777 were standard reference works on the British flora.
Koch 1843–4. See letter from C. C. Babington, 22 November 1856, n. 2.
See letter from George Dickie, 1 December 1856. George Dickie was professor of natural history at Belfast University, but was particularly noted for his botanical studies of the area around Aberdeen, his birthplace (R. Desmond 1977).


Responds to CD’s query on Subularia and Limosella. There are discrepancies among authorities on whether Subularia flowers out of water. Limosella certainly flowers out of water.

Letter details

Letter no.
Hewett Cottrell Watson
Charles Robert Darwin
Sent from
Thames Ditton
Source of text
DAR 207: 19
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 2002,” accessed on 20 March 2019,

Also published in The Correspondence of Charles Darwin, vol. 6