NUMBERS OF FLORAL ORGANS. 



31 



double flowers, of course it is requisite to procure specimens that 

 have undergone no change. Ordinarily every flower keeps to its own 

 multiples, five or ten sepals implying five or ten petals, and five or 

 ten petals implying five or ten stamens, &c. ; but sometimes the 

 numbers are a little intermingled, as three with five, and two with 

 five. In such cases it is judged by the predominant number, or by 

 analogy, to which of the three great classes the flower belongs, the 

 corolla being consulted first, then the calyx, and lastly the stamens. 

 With unisexual flowers, it is safest to take the male or stamen-bearing. 

 These three great types of floral structure, as regards number, are 

 called " pentamerous," " tetramerous," and " trimerous," the first 

 including such as are formed upon the number five, and its multiples ; 

 the second, those in which the number four, with its multiples, is 

 predominant ; and the last, such as illustrate the number three, and 

 this whether the perianth be single or double, and the corolla regular 

 or irregular. (Figs. 62, 63, 64.) 



Fig. 62. 

 Pentamerous flower. 



Fig. 64. 

 Trimerous flower. 



Fig. 63. 

 Tetramerous flower. 



Compound Flowers. 



The preceding descriptions, as stated at the commencement, apply 

 to "complete" and "simple" flowers. We will now consider the 

 second great division, denominated " compound," and comprising such 

 forms as the daisy, the aster, and the sun-flower. Their characters 

 are strikingly distinct, and though occasionally found separately else- 

 where, collectively they are peculiar to the family which includes the 

 plants just mentioned, so that a description of compound flowers and 

 a description of the Daisy-family amounts very nearly to the same 



