FLORA'S CLOCK. 



occur with the same regularity, and when vegetation is injured 

 by any circumstance, it may have barren years. It has also 

 been observed, that when a tree has borne a great deal of fruit 

 one year and retained it late, inflorescence is feeble or entirely 

 wanting the succeeding year ; and thus it is in the south of 

 Europe, when the olives are left late upon the trees, the harvest 

 fa:ls the following year. Sometimes, on the contrary, the periods 

 of inflorescence are more approximated, and in warm and humid 

 autumns, we occasionally see plants flowering a second time. 



4. The period of the year at which inflorescence takes place 

 is generally definite for each species of plant, but varies a little 

 according to the temperature and other atmospheric circum- 

 stances. For example, in the climate of Paris (which is similar 

 .o that of the Middle States), the black hellebore flowers in 

 January ; the hazel tree and willow in February ; the box, the 

 yew, the almond, the peach, the apricot, the primrose, the stock- 

 gilly flower, in March ; the plum, the pine, the ash, the elm, the 

 yoke-elm, the hyacinth, the dandelion, &c., in April ; the apple, 

 the horse-chestnut, the lilac, the cherry, the peony, in May ; the 

 iinden tree, the vine, oats, wheat, the wild red poppy, larkspur, 

 in June ; the violet, the carrot, hemp, lettuce, in July ; asters, 

 garden-balsams, and water-hyssop, in August ; ivy, saffron, in 

 September; Jerusalem artichoke and certain other plants, in 

 October. The table of the different epochs of inflorescence con- 

 stitutes what botanists have named Flora's calendar. In colder 

 countries, inflorescence is retarded, while in the South it occurs 

 earlier; for example, in Smyrna, the almond flowers in the first 

 fortnight of February; in Germany, in the second half of April; 

 and in Christiania (Sweden), in the first da v s of June. 



5. The expansion or blooming of the flower is 

 almost always effected by the separation of the 

 pieces of the corolla and calyx from above down- 

 wards ; but there are some in which the floral in- 

 teguments ^emain adherent to the summit, and 

 separate at the base, as in the vine, for example 

 (/. 115). 



6. The period of the day at which this phenomenon occurs 

 varies in the greatest number of plants, but in some it is fixed, 

 and a series of plants arranged according to the hour at which 

 the flowers blow, constitutes what Linnaeus called Flora's clock. 

 For example, at Paris, the bearbind (a species of bind-weed) 

 blows between three and four o'clock in the morning ; between 



4. Does inflorescence recur in the same species of plant at the same 

 period ' What is meant by Flora's calendar ? 



5. How does a flower expand ? 



(i. What is meant by Flora's clock.? 



