CHAP. V. FUNCTION OP REPRODUCTION. 255 



Linnaeus and others have prepared tables of different 

 plants, which flower in each month of the year, under 

 the title of Flora's Calendars. 



(250.) Horary Expansion. As the flowering of 

 different species takes place at different seasons of the 

 year, so also many species open their flowers only at 

 certain hours of the day. The greater number are 

 not subject to any very marked law in this particu- 

 lar ; and their flowers, wheri once expanded, continue 

 open until they decay. Some flowers, as those of the 

 purple horned-poppy (Rcemeria violacea), expand early 

 in the morning, and their petals are so very fugacious, 

 that they are mostly fallen two or three hours before 

 noon. But there are many plants, as the Convolvulus 

 nil, which retain their corolla for several days, and 

 regularly open and shut it at certain hours. Linnaeus 

 prepared tables to express these facts, which he fanci- 

 fully termed Flora's clocks. The following list may 

 serve as a specimen. 



A. M. 



4. Convolvulus nil. 



5. Papaver nudicaule. 



5 6. Convolvulus tricolor. 



6' 7- Sonchus oleraceus. 



8. Anagallis arvensis. 



9. Calendula arvensis. 



11. Ornithogalum umbellatum. 



12. Mesymbrianthemum. 

 p. M. 



2. Scilla pomeridiana. 



5 6'. Silene noctiflora. 



6 7- Nyctago jalapa. 



7 8. Cereus grandiflorus. 



10. Convolvulus purpureus. 



He named those flowers " Ephemeral," which open 

 once only at a given time, and decay within the period 

 of a day ; and those " Equinoctial," which open and 

 close for several days at the same hour. Of these, 



