22 SLEEP OF FLOWERS. [chap. I. 



its name " day's-eye." The Dandelion {Leontodon 

 Taraxacum) is said to open about seven and close 

 about five ; A renaria rubra to be open from nine to 

 three ; ^ Nymphaa alba from about seven to four ; the 

 common Mouse-ear Hawkweed [Hieraciiim Pilosella) 

 from eight to three ; the Scarlet Pimpernel {Ana- 

 gallis arvensis) to waken at seven and close soon 

 after two ; Tragopogon pratensis to open at four in 

 the morning, artd close just before twelve, whence 

 its English name, "John go to bed at noon." Far- 

 mers' boys in some parts are said to regulate their 

 dinner-time by it. Other flowers, on the contrary, 

 open in the evening.'^ 



Now, it is obvious that flowers which are fertilised 

 by night-flying insects would derive no advantage from 

 being open by day ; and on the other hand, that those 

 which are fertilised by bees would gain nothing by 

 being open at night. Nay, it would be a distinct dis- 

 advantage, because it would render them liable to be 

 robbed of their honey and pollen, by insects which 

 are not capable of fertilising them. I would venture 

 to suggest, then, that the closing of flowers may 

 have reference to the habits of insects, and it may be 

 observed also in support of this that wind-fertilised 

 flowers do not sleep ; and that some of those flowers 

 which attract insects by smell, emit their scent 

 at particular hours ; thus, Hesperis matroiialis and 

 Lychnis vespertina smell in the evening, and Orchis 

 bifolia is particularly sweet at night. 



• In my own observations the opening and closing was more gradual 

 and more dependent on the weather than I should have expected from 

 the statements quoted above. 



