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Darwin Correspondence Project

To W. T. Thiselton-Dyer   15 April 1880

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

Ap. 15th 80

My dear Dyer

If you chance to have seeds of Impomœa pandurata, a few would be of inestimable value to me.1 Or indeed of any kind (except I. leptophylla which I have) which forms a great tuber-like root.2

Do not answer this.— I know that it is only a forlorn hope.—

Ever yours | C. Darwin

Asa Gray has told me of I. pandurata & admits that if its seeds germinate like those of I. leptophylla, a pet little theory of mine wd. be well confirmed.— He was, I think, at first inclined to treat my little theory with sovereign contempt.3


Ipomoea pandurata (man-of-the-earth or wild potato vine) is a species native to North America, notable for its large tuberous roots.
CD recorded the germination of plants of Ipomoea leptophylla (bush morning-glory), another species with large tuberous roots, on 14 April 1880, noting that the petioles were buried about a half inch below the ground (DAR 209.6: 95).
See letter from Asa Gray, [1 April 1880] and n. 3. See also enclosure to letter from Asa Gray, 4 April 1880, in which a correspondent of Gray’s confirmed CD’s observations about the burying of petioles in another plant with tuberous roots. CD hypothesised that the buried petioles acted functionally like a root to hide the tuberous root from predators.


Wants Ipomoea seeds for observing germination.

Letter details

Letter no.
Charles Robert Darwin
William Turner Thiselton-Dyer
Sent from
Source of text
Royal Botanic Gardens, Kew (Darwin: Letters to Thiselton-Dyer, 1873–81: ff. 205–6)
Physical description
ALS 2pp †

Please cite as

Darwin Correspondence Project, “Letter no. 12576,” accessed on 16 August 2022,