From W. E. Darwin   18 April 1864

Southampton & Hampshire Bank, | Southampton

April 18 1864

My Dear Father

There is not the least doubt that you are right as to its being only variability.1

first as to the Short styled.

Among the few flowers I got at my first visit there was only one with the short filaments i.e. with the stamens within the tube which was the one I wrote to you about & was so withered I could not draw it2

I went again yesterday & examined from 85 to 90 plants,3 & could not find a single short styled plant with the stamens entirely within the tube; I did find a single Case in which (all through the plant) the stamens were about $\frac{1}{2}$ in & $\frac{1}{2}$ out of the tube as you will see I have drawn.4 in all others short styled plants the stamens were well out of the tube tho’ perhaps the filaments were a very little longer in some cases than others.5

I measured the pollen in this shorter filamented one, & as you see it is exactly same size as the other.

2ndly. Long styled.

The stamens are always the in same position.

The length of pistil varies in length from just above the bristles to the base of the division in the petals.6

I measured the pollen of two sets of Long & shorter styled and you see they are just the same size, and always smaller than the short styled pollen.7 I did not measure the stigmas again as it did not seem worthwhile.8

I will send a line when I should like to be sent for on Friday.9

Your affect son | W E D.

[Enclosure]10

short styled

Long filaments

The only case of shorter filaments

pistil in each case only reaching up to base of division of sepals

pollen in each case exactly same size

Some of the filaments appear very slightly longer than others

Long styled

stamens always in same position

pistil varies in length from just above the hairs in base of corolla to base of petal, or from base of Division of sepals to rather above their tips

Measured the pollen in longest & shortest styled Long styled   the same size or if there was any difference the Longest styled is the largest

style nearly always constant for each plant in length, but not quite

Short filaments Short styled ordinary long filaments

Long styled

Shorter Style

Long style

pulmonaria

Long styled

Long styled

Shorter Style

Long style

CD annotations

Cover: ‘2d letter | does stigma on short style correspond in height to anther in long-styled??’11 pencil, del pencil; ‘How much longer one pistil than other?’ pencil, bracketed and del pencil; ‘Variability’12 pencil, del pencil; ‘Roughness of stigma’ pencil, del pencil; ‘April 18thpencil; ‘3’13 red crayon, circled red crayon
Verso of cover: ‘Pulmonaria | April 18thpencil; ‘3’ red crayon, circled red crayon
Enclosure: ‘3’ red crayon, circled red crayon; ‘April 18thpencil, circled pencil *S1 !alignleft!CD note: *S2 William says that in long-styled, extreme variation in length of pistil excessively common. from just above tube to base of division of corolla— In short styled stigma reaches up to base of division of [‘corolla.’ del] calyx—

Footnotes

CD’s letter has not been found; however, CD may have referred to William’s earlier observation that the stigma of the short-styled form of Pulmonaria angustifolia had the longest papillae (see letter from W. E. Darwin, 14 April [1864] and n. 5). See also William’s comment at the end of this letter that it did not seem worthwhile to include measurements of the stigmas, and CD’s annotation, which he crossed out: ‘Roughness of stigma’. However, see also n. 12, below.
William was assisting CD with observations and measurements of Pulmonaria angustifolia, and had recently collected P. angustifolia on the Isle of Wight, as he had in 1863 (see letter from W. E. Darwin, 14 April [1864] and nn. 1 and 6, and letter to W. E. Darwin, [after 14 April – 5 May 1864] and n. 2). William wrote about the one short-styled flower with short filaments that had withered in his letter of 14 April [1864].
CD mentioned William’s observation and collection of Pulmonaria angustifolia on the Isle of Wight in Forms of flowers, pp. 105 and 107.
See the enclosure for William’s drawing and notes on the one short-styled flower with shorter filaments.
In Forms of flowers, p. 105, CD noted the variability in the distance between the pistils and stamens of Pulmonaria angustifolia, particularly in the short-styled form.
CD noted the variation of the pistil length in the long-styled form in the CD note to this letter, and in his abstracts of William’s letters in DAR 110: A53 (see CD annotations, and letter from W. E. Darwin, 14 April [1864] and n. 2).
See the enclosure for William’s two drawings. On the difference in pollen sizes for Pulmonaria angustifolia and other heterostyled species, see letter from W. E. Darwin, 14 April [1864] and n. 4.
See letter from W. E. Darwin, 14 April [1864] and n. 5, and n. 1, above.
The sketches of the flowers are reproduced at their original size. The sketches of pollen grains are all reproduced at 45 per cent of their original size.
In Forms of flowers, pp. 105–6, CD included measurements of the distances between stigmas and anthers in the different forms, concluding that ‘the stigma in the one form does not stand on a level with the anthers in the other’, and noting that the long-styled pistil was sometimes three times as long as the short-styled. See also the note in DAR 110: A43.
William’s observations and CD’s own, later, observations led CD to conclude that the different filament lengths in the short-styled forms, the different pistil lengths in the long-styled forms, as well as the lengths of the papillae on the stigmas, were due merely to variability (see nn. 1, 5, and 7, above; letter from W. E. Darwin, 14 April [1864] and nn. 2 and 5; and Forms of flowers, pp. 105–6).
See n. 6, above. The circled numbers are some of William’s letters, covers, or enclosure regarding pulmonaria angustifolia correlate with similiar numbers on CD’s abstracts of the letters in DAR 110: A53.

Bibliography

Forms of flowers: The different forms of flowers on plants of the same species. By Charles Darwin. London: John Murray. 1877.

Summary

CD is right about variability [of Pulmonaria]. Encloses observations and diagrams of additional plants.

Letter details

Letter no.
DCP-LETT-4466
From
William Erasmus Darwin
To
Charles Robert Darwin
Sent from
Southampton
Source of text
DAR 110: A77–81b
Physical description
4pp ††, encl 5pp †