Ɛpsilon

From Asa Gray   3 July 1880

July 3, 1880

Here is a confirmation of your idea, illustrating how well you hit.1 I got a few seeds of Ipomœa pandurata, the species of Atlantic U.S. with a huge root. One seed only has yet come up. Its germination is same as of I. leptophylla, viz. caulicle remains shut and petioles of cotyledons lengthen & bring up the cotyledons.2 The caulicle lengthens a little—is 14 inch, the petioles are 2 inches long.

A. Gray

ApcS

1
See letter to Asa Gray, 19 January 1880. CD had described his observations on the germination of Megarrhiza californica (a synonym of Marah fabacea, California manroot), noting that the growth of the radicle or embryonic root seemed to be arrested, while the tubular petiole penetrated the ground and grew to a depth of more than two inches.
2
Ipomoea pandurata (man-of-the-earth or wild potato vine) and I. leptophylla (bush morning-glory) are North American species with large tuberous roots. Gray had earlier told CD he thought germination occurred normally in these species, but would investigate further (letter from Asa Gray, [1 April 1880]). In Gray’s usage, the caulicle was the initial stem in an embryo (A. Gray 1879, p. 401).

Please cite as “DCP-LETT-12646F,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-12646F