Ohfervatwns on the Flowering of certain Plants, 159 



The three plants (Anagallis arvenfis, Oenothera biennis, Hibifcus 

 frionum) which were fele&ed for thefe obfervations, were taken 

 rather for the convenience of their fituation, from their vicinity to 

 the houfe, than for any other reafon. Anagallis arvenjls, however, 

 is a delicate wild plant, that has long; fmce attracted notice, as indi- 

 cating rainy weather or a moift atmofphere by the clofing of its 

 flowers, and the contrary by their opening. Hence its name among 

 the country people, of Shepherd's or Poor mans weather-glafs. And 

 Oenothera biennis has been generally regarded, from an early period, 

 for the regular opening of its flowers in the evening, and has 

 thence obtained the name of Evening or Nightly Primrofs. 



The flowers of the Oenothera are collected in a very clofe corvm- 

 bus at the top of the ftalk till the time of flowering. The upper 

 flowers expand firft; and as they expand fucceflively, the ftalk is-ad- 

 vancing in height, and feparating the flowers ; infomuch that when 

 the flowering time is pad, there is the fpace of a foot or eighteen 

 inches inferpofed between thofe flowers which were originally 

 contiguous. Whilfl: each flower is preparing for expanfion, the 

 peduncle gradually diverges from the ftem, and, before the flower 

 opens, arches downwards like a fwan's neck: the corolla fwells 

 out at bottom, and is very apparent there between the leaflets of 

 the calyx, which keep it clofe together for a confiderable time at 

 top, by means of the hooks at the extremity of the calycine leaflets, 

 till at length the corolla burfts its bonds initantaneoufly, opens to a 

 certain point, and then having made a ftand for a few feconds, ex- 

 pands very (lowly to its full extent. This critical moment is very 

 interefting to the botanical obferver, and may be feen with eafe and 

 pleafure between fix and feven within the houfe, by gathering the 

 flowers and fetting them in water. In hot weather the flowers 





grow 



