128 THE SECOND BOOK OF BOTANY. 



take care to select the straightest and thriftiest stems 

 for the purpose. 



Examine the arrangement of bracts, and see if 

 they follow the same order as leaves. 



Observe whether the spirals take the same direc- 

 tion in branches as in the parent stem. When they 

 do, they are called homodromous / but when they 

 turn in opposite directions, they are said to be hetero- 

 dromous. 



Give the numbers of the leaves in each perpen- 

 dicular series in your specimen showing the |- ar- 

 rangement (Fig. 268). 



In the -J arrangement, what leaf stands over the 

 first? over the second? the third? fourth? fifth? 

 Give the series of numbers that belong to the leaves 

 of each row. 



The name applied by botanists to these modes of 

 leaf-arrangement is phyllotaxis. 



EXERCISE XLIV. 



Arrangement of Floral Leaves in the Bud. Esti- 

 vation, or Prcefloration. 



In most common flowers, the floral circles, calyx, 

 corolla, etc., appear quite distinct ; but have you 

 never observed cases in which it was doubtful where 

 the calyx ended and the corolla began ? or, where the 

 corolla ended and the calyx began ? or, even, where 

 the bracts ended and the calyx began ? Have you 

 never seen petaloid sepals? that is, sepals with the 



