Oil the Movements of Petals 3 



in flax {Linum usitatissimuni) . The corolla may also change 

 in color upon withering, as in the evening primrose (Pachylophus 

 caespitosus), the waxy white petals turning a dull pink upon 

 withering. 



The life of an individual flower varies from a few hours, as 

 in the ephemeral species, to many days. According to Kerner 

 and Oliver, the range is from 3 hours (in Hibiscus trionum) to 

 80 days (in Odontoglossum rossii). Whether the length of life 

 of an individual flower and the closing at certain hours have 

 anything to do with the pollination of the flowers by certain 

 insects is not a question to be discussed here, however interesting 

 it may be. The two are closely connected but are not cause and 

 effect. 



Following is a list of plants which show these movements, 

 those preceded by a * having been experimented upon directly; 

 the others were simply observed. The list is very small when 

 compared with the cases actually known, since it simply includes 

 those coming under personal observation within the last two or 

 three years : 



■ I. Day bloomers, 



1. Opening and closing repeatedly. 

 Ao^oscris greenei, (Gray) Rydb. 

 Claytonia virginica L. 

 Croais vernus All. 

 Erigeron flagellaris Gray 

 Geniiana acuta Michx. 

 Gentianafrigida Haenke 

 Geniiana parryi Engelm. 

 Laduca sc.^riola L. 

 ]\fdchaeranthera aspera Greene 

 J^osa TV odsii Lindl. 



* Ta ax€u:um taraxacum 

 Tiilipa gesneriana L. 



2. Opening and closing but once, 1 day or less. 

 Epilobhini adenocaulon Haussk. 

 Erytlironitim albidum Nutt. 

 Specularia perfoliata (L.) A.DC. 



*Linutn usitatissiniuvt L. 

 *Oxalis siricia L. 

 Portutacaoleracea'L. 10:00-11:00 3:00-4:00 



