STRUCTURE OF FLOWERS. 41) 



in most of those which are incomplete. It is formed 

 of pieces which are disposed in verticils in one or two 

 rows, and which bear the name of Sepals, (sepala.) 



The sepals are evidently organs very analogous to the 

 nature of leaves: and it might be said with some reason, 

 that they are bracts which constantly exist, and form 

 an integrant part of the flower. The identity of nature 

 of the sepals, bracts and leaves, is derived from the fol- 

 lowing facts : — 1st. Their internal anatomy presents 

 vessels and tracheae as in leaves, and their tissue presents 

 most frequently a great analogy in the distribution of 

 the fibres. 2d. Their surface, as that of leaves, presents 

 stomata, most frequently distributed in the same manner 

 in the same plants. 3d. When they have glands or 

 hairs, these organs are similar in their nature, form, or 

 position, to those of leaves. 4th. They are almost 

 always green, as leaves, and endowed, as they are, with 

 the faculty, both of becoming etiolated in darkness, of 

 decomposing carbonic acid gas, and of exhaling oxygen 

 when placed in water under the sun. 5th. Lastly, 

 they take, under several accidental circumstances, an 

 extraordinary development, and then they absolutely 

 resemble true leaves, as is frequently seen in Roses, 

 for example, (PI. 17.) We may regard the sepals, 

 then, rs bein? of a foliaceous nature: and it may 

 be said that they are kinds of floral leaves, which by 

 their position take particular forms, and serve as the 

 outer covering of the flower. They are, as leaves, some- 

 times articulated at their base, and then they become 

 detached and fall off spontaneously, either at the com- 

 mencement of the flowering, as in the Poppy, or at the 

 conclusion of it, as in Ranunculus ; sometimes they are 

 continuous, or adherent at their base, and then they do 

 not drop off, and are said to be Persistent. But then 

 they either dry up after flowering, and are termed Mar- 



vol. II. E 



