Ɛpsilon

From Hubert Airy   21 July 1872

13. Eliot Place. | Blackheath. S.E.

1872. July 21.

My dear Sir

I am afraid I made a bad mistake in my letter yesterday, in saying that the leaf belonging to the topmost node in grass-stems is obsolete. On examination I see that the leaf is fully developed; and I hope you will obliterate that passage from my letter.1

With this, I send one or two lilac twigs, which present a characteristic series of variations from the normal 2-whorl, in illustration of the ‘nodal’ question.2

I could also show you an oak-twig affecting a succession of 3-whorls with long internodes from whorl to whorl; as a specimen of variation from the alternate towards the verticillate arrangement.3

I am, my dear Sir, | Yours very truly | Hubert Airy

2
In Airy 1874, pp. 304, Airy discussed variability of the number of leaf-ranks in the same species, giving as an example whorls of three being produced by plants like lilacs that usually bear whorls of two. The ‘nodal’ question relates to Airy’s view that the node had no independent importance and existed only as the starting point of the leaves (see letter from Hubert Airy, 20 July 1872 and n. 1).
3
The variation in oak showing the alternate going to a verticillate (or whorled) arrangement involved an increase from one leaf per node to three per node.

Please cite as “DCP-LETT-8422,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-8422