Ɛpsilon

From Asa Gray   29 July [1880]

July 29—

Thanks for your postal1

Ipomœa jalapa (Conv. I. macrorhizus. Ell.) of S. Carolina, with a large turnip-like root, sometimes 40–50 lbs, makes only moderately long petioles cotyledons & lengthens the caulicle considerably— — has not caught the trick, but has some idea of it.2

A. Gray

ApcS

Postmark: JUL 80

1
CD’s postcard has not been found, but see the letter from Asa Gray, 3 July 1880. Gray had written about germination in two species of Ipomoea.
2
Ipomoea jalapa is a synonym of I. purga (jalap), a species native to parts of Mexico. Ipomoea macrorhiza is largeroot morning-glory, a species native to South Carolina; Gray may have accidentally conflated the names, but evidently intended I. macrorhiza. In Gray’s usage, the caulicle was the initial stem in an embryo (A. Gray 1879, p. 401). The ‘trick’ refers to the method of germination, which, in the case of some other species of Ipomoea, involved the caulicle remaining shut while the petioles lengthened and brought up the cotyledons (letter from Asa Gray, 3 July 1880).

Please cite as “DCP-LETT-12674F,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-12674F