40 



MORPHOLOGICAL BOTANY. 



Fig. 43. 



below the leaves at the third node, and the leaves at the second node lie 

 opposite to those at the fourth node, and so forth ; hence, in this case there 

 are found four longitudinal series of leaves placed up and down. 



These longitudinal series of leaves 

 are called Orthostichies or Vertical 

 Ranks. 



In the whorl consisting of three 

 leaves (Fig. 42), the anglar divergence 

 must be one-third of the circumference, 

 as the distance between any two 

 adjacent leaves is equal. In this case 

 also, the leaves at any two adjacent 

 nodes alternate, so that the leaves < 

 at the first node lie opposite to the 

 leaves at the third node, and so on ; 

 hence, there will be six longitudinal 

 series of leaves placed up and down, or 

 six vertical ranks of leaves. 

 If a whorl consists of four leaves, the angular divergence will be one- 

 fourth of the circumference and there will be eight vertical ranks of 

 leaves. 



In the other kinds of verticillate leaves also, the angular divergence is 

 usually found to be a fraction that has one for its numerator and the 

 number of leaves at one node for its denominator, and the number of 

 vertical ranks is just twice the number of leaves at one node. 



Fig. 44. Fig. 45. 



Fig. 43. — Diagram of a stem with 



opposite leaves ; 1, 2, 3, 4, 5, 6, 



the successive -whorls. 



(Prantl.) 



Fig. 44. — Diagram of a stem 



bearing alternate leaves with a 



divergence of J ; 1, 2, 3, 4, 5, 6, 



the successive leaves. 



(Prantl.) 



Fig. 45. — Diagram of a stem 



bearing alternate leaves 



with a divergence of J. 



(Prantl.) 



