Q02 LETTER XVII. 



round a number of flowers. You have already had 

 an excellent instance of it in Umbelliferous plants, 

 and this is another. 



Rousseau took the Daisy to explain the structure 

 of Composite flowers, because it is so very common a 

 plant ; but it has the defect, as a means of illustration, 

 that its parts are so very small, as to be distinguished 

 with difficulty, and that it does not comprehend so 

 many points of structure as some others. For these 

 reasons, I will recommend you to take a plant equally 

 common in gardens in the autumn, the French Ma- 

 rigold (Tagetes patula, Plate XVII. 1.), an old- 

 fashioned, but pretty flower, which is not liable to 

 the same objections. 



Its flower-head (fg. 1.) is surrounded externally by 

 an olive green cup, formed of several bracts which 

 have gi'own together at the edge {Jig. 6.) ; this cup 

 is the involucre. Next the involucre are placed 

 several florets {Jigs. 1. & 2.), whose corolla is a broad 

 yellow blade, rounded at the end, and striped with 

 wide streaks of chocolate brown (Jig. 2. d.) -, it is all 

 turned one way, spreading away from the flower- 

 head, and only tubular at the bottom ; Rousseau says, 

 such corollas look as if they were gnawed ofl" on one 

 side. Technically, they are named ligulate, which 

 signifies strap-shaped, because in the greater part of 

 Composite flowers they are long and narrow ; they 

 are also said to form the ray of the flovver-hcad. At 

 the base of the tube of the corolla you will find a few 

 little narrow hairy scales {fg. 2. h.), which stand on 

 the top of the ovary, in the place of the calyx. Bo- 



