# To Daniel Oliver   11 March [1864]1

Down Bromley | Kent.

Mar 11

My dear Oliver—

Will you be so kind as to give me your opinion on the following point? I was so much struck with the corresponding position of tendril & flower stalk in Passiflora that I got my son William2 (who can dissect under a $\frac{1}{10}$ & can draw) to examine these parts in their earliest stages. In the enclosed drawing (which please to return) you will see Fig. 1 the tendril & flower bud apparently quite confluent which seems odd.3 From Fig. 2. to 7 you will see the gradation. The sort of horn to the left is the outer division of the involuca which in the early stages is the most developed.4 In one single case of an old bud Fig. A my son found the top of the tendril absolutely like a flower bud in an early stage as in Fig. 3 or 4.5

Does not this render it highly probable that the tendril is a modified flower with its peduncle?6 I presume that a flower wd be called by you an axillary part??7 & that in the vine the tendril might be considered a modified flower peduncle as I now see Lindley maintains that it is.8

It wd I have reason to think be a considerable relief to me, if I might view such tendrils as modified flower stalks instead of modified branches9

Pray tell me is there any essential distinction between the peduncle & mid rib of a leaf, & a branch? for does not a leaf some times produce buds?10

It wd a great kindness if some day you wd look at the plants of Tecoma Radicans & observe if the branches spirally twine—11 I suppose they do not—

Also wd 〈y〉ou look at Tecoma Undulata & Capensis— How can they climb? Do they twine or do they emit rootlets like T. Radicans? My plants tho’ 4 ft. high shew no signs of climbing.12 I am much interested about the Genus Tecoma.

Believe me dear Oliver | yours very sincerely | Ch. Darwin

## [Enclosure 1]

[diag here]

Passiflora floribunda13

## [Enclosure 2]

Passionflower

floribunda

tendrils appear on different sides of flower, but in same branch on the same side.

## Footnotes

The year is established by the relationship between this letter and the letter from Daniel Oliver, 12 March 1864.
William Erasmus Darwin, CD’s eldest son.
For the figures, see the first enclosure. The flower bud (‘fl’) of Passiflora floribunda is labelled on one side of the plant part William dissected, and the tendril is labelled on the other side. When CD referred to William’s drawings in his discussion of Passifloraceae in ‘Climbing plants’, he stated that the confluent tendril and flower bud at first appeared as a single papilla that gradually divided (‘Climbing plants’, p. 89).
The involucre is a whorl of bracts beneath an inflorescence.
CD added the label ‘Abnormal Flower’ to figure A (see enclosure 1, and n. 13, below).
In ‘Climbing plants’, p. 89, CD concluded that Passifloraceae tendrils were modified flower peduncles. See also letter to J. D. Hooker, [27 January 1864] and nn. 19 and 20, and memorandum and letter from Daniel Oliver, [28 January – 8 February 1864] and 12 March 1864.
An axillary structure is one that lies in the axil, or the upper angle between the stem and a leaf (see Gray 1857, p. 206). In his memorandum of [28 January – 8 February 1864], Daniel Oliver stated that the tendrils of some plants might be modified axillary branches or leaves. See also letter from Daniel Oliver, 12 March 1864, and ‘Climbing plants’, pp. 113–14.
John Lindley wrote that the peduncles of vines (Vitaceae) are ‘racemose, sometimes by abortion changing to tendrils, often opposite the leaves’ (Lindley 1853, p. 439), also noting that the tendrils ‘are the branches of inflorescence, the flowers of which are abortive’ (ibid., p. 440). In an undated note in DAR 157.2: 78, CD mentioned Lindley’s comment and discussed the possibility that Passifloraceae tendrils might also be derived from flower peduncles; the note includes his sketch of a bud, tendril, flower, and leaf on a branch.
CD had been trying to determine from what plant part tendrils in different families were derived (see letters to J. D. Hooker, [27 January 1864] and nn. 19–23, and [8 February 1864] and n. 10).
See letter from Daniel Oliver, 12 March 1864, and ‘Climbing plants’, pp. 113–14.
There is a note dated 21 February 1864 in DAR 157.1: 59 that mentions Tecoma radicans; it appears to be an early draft of parts of pages 105–6 of ‘Climbing plants’. See also note on T. radicans dated 10 March 1864 in DAR 157.1: 60, and ‘Climbing plants’, pp. 25, 114.
CD acquired Tecoma undulata and T. capensis from Joseph Dalton Hooker in 1863, when he was seeking plants for his new hothouse (see Correspondence vol. 11, Appendix VI).
The labels on William’s sketches were written by CD and William. The sketches are reproduced here at 90 per cent of their original size.

## Summary

Struck with corresponding positions of tendrils and flower-stalks in Passiflora. Sends [W. E. Darwin’s] dissection drawings of earliest stages. Infers that tendril is a modified flower peduncle.

Requests DO look at mode of climbing in Tecoma.

## Letter details

Letter no.
DCP-LETT-4424
From
Charles Robert Darwin
To
Daniel Oliver
Sent from
Down
Source of text
DAR 157.2: 69–70; DAR 261.10: 40 (EH 88206023)
Physical description
6pp †