# To W. E. Darwin   3 May [1864]1

My dear William.—

I send some flowers of long & short-styled Pulmonaria & I shd be very much obliged for mere outline of size of anthers of the 2 forms by the camera, that I may truly compare sizes; this being very important for me.—2

Very many thanks for measures of pollen of red cowslip: I am very much surprised at its size:3 I must, however, beg you to measure once again the grain in comparison with those of the short-styled wild cowslip; taking care that the latter have soaked rather the longest.4 I will send other flowers as soon as I have any.

Yours affect. | C. Darwin

May 3d.—

You had better brush off the pollen.—

P.S. Will you notice in the young anthers, perhaps pollen is shed whether there seems to be more pollen in the one form than in the other?—5

I am too bad to observe it.6

## Footnotes

The year is established by the fact that William examined Pulmonaria angustifolia in 1863 and 1864, and measured the pollen of the red equal-styled cowslip in 1864 and 1865; both activities are mentioned in this letter (see letters and memorandum from W. E. Darwin, 14 April [1864], 18 April 1864, and [30 April 1864], and nn. 2, 3, and 5, below).
William used a camera lucida to make many of his botanical drawings (see Correspondence vol. 10, letters from W. E. Darwin, 1 August 1862 and 5 August 1862). CD had earlier considered the length of anthers as an indication of dimorphism (see, for example, Correspondence vol. 10, letter to Asa Gray, 16 February [1862], and Correspondence vol. 11, letter from John Scott, [3 June 1863]). In notes on Pulmonaria angustifolia dated 26 April, 6 May, and 14 May 1864, he made several observations of anther size in the long-styled and short-styled forms, noting on 6 May 1864 that the anthers in the P. angustifolia bud were about one-third longer on the short-styled flowers, and noting on 14 May that the length was very variable (see DAR 110: A43, A51, and A51 v.). He published this conclusion in Forms of flowers, pp. 106 and 252, adding that the ratio of anther length in short-styled to anther length in long-styled was 100 to 91; he noted that measurements of both forms revealed that the longer anther lengths appeared more often in the short-styled than in the long-styled form, as in most heterostyled species (see also experimental notes in DAR 110: B15–17 and DAR 111: 9a). For William Erasmus Darwin’s sketches of Pulmonaria anthers, see the memorandum and the letter from W. E. Darwin, 6 May 1864 and 12 May [1864]; for his sketches of anthers in the bud, see the letters from W. E. Darwin, 18 May [1864] and 24 May 1864. See also letter to W. E. Darwin, 14 May [1864] and n. 5.
See memorandum from W. E. Darwin, [30 April 1864] and n. 2. CD wrote that the pollen of the equal-styled plants that he grew from John Scott’s plant resembled the pollen from the short-styled form but included a few shrivelled grains (see Forms of flowers, pp. 235–6). See also ‘Illegitimate offspring of dimorphic and trimorphic plants’, p. 427. For CD’s general remarks on pollen size in heterostyled species, including Primula veris, see Forms of flowers, pp. 248–52.
CD refers to the short-styled form of the yellow cowslip (Primula veris) (see the memorandum from W. E. Darwin, [30 April 1864]).
CD presumably refers to the Pulmonaria anthers of which he requested drawings (see n. 2, above). William responded to his question in his letters of 12 May [1864] and 18 May [1864].
According to Emma Darwin’s diary (DAR 242), CD was ‘uncomf[ortable]’ on 2 and 3 May 1864.

## Summary

Thanks WED for measuring cowslip pollen. Sends dimorphic flowers.

## Letter details

Letter no.
DCP-LETT-4480
From
Charles Robert Darwin
To
William Erasmus Darwin
Sent from
unstated
Source of text
DAR 97: A8, A10
Physical description
3pp