Note 12 — Chapter VI · MODIFIED CIRCUMNUTATION: SLEEP OR NYCTITROPIC MOVEMENTS, THEIR USE: SLEEP OF COTYLEDONS.
Reading edition
We were surprised that young seedlings of so tropical a plant as Mimosa pudica were able to resist, as well as they did, exposure for 1 hr. 45 m. to a clear sky, the temperature on the surrounding ground being 29° F. It may be added that seedlings of the Indian ‘Cassia pubescens’ were exposed for 1 h. 30 m. to a clear sky, with the temp. on the surrounding ground at –2° C., and they were not in the least injured.