4 ARRANGEMENT OF ORGANS. 



raent obtains in the ordinary leaves, the parts of tlie 

 flower may be disposed according to the other method. 

 In the annular disposition it generally happens that 

 the rings are separated one from the other by the 

 development of the stem between them, the internodes 

 between the constituent leaves themselves of course 

 being undeveloped ; on the other hftnd, in the spiral or 

 successive arrangement tliere is no such alternate 

 growth and arrest of growth of the stem between the 

 leaves, or between successive cycles, but the growth is, 

 under favorable conditions,continuous leaf is separated 

 from leaf, and cycle from cycle, by the continually 

 elongating stem. Thus, the two modes of growth cor- 

 respond precisely with those observed in the case of 

 definite and indefinite inflorescence respectively. 



The same arrangements, that are observed in the 

 disposition of the leaves, apply equally well to the 

 several parts of the flower ; thus, in what is for con- 

 venience considered the typical flower, there is a calyx 

 ^^ ..^^^^^ of five or more distinct sepals, equal 

 ^ >==v N\ in size, and arranged in a whorl, a 

 J* (^ \ corolla of a similar number of petals 

 <^^ ' \ alternating with the sepals, five 

 k CD A j] stamens placed in the same position 

 ^^=^ -^ J^ with reference to the petals, and 

 '^'==:=r::=:^ fivc carpcls alternating with the 



Fio. 1. Diagram stamens. Throughout this book 



showing the arrange- ^, . . , i ,i 



ment of parts in a com- this arrangement IS taken as the 

 piete, regular, penta- standard of reference. Neverthe- 



meroos flower: , sepals; 



j, petals; < stamens; less the Spiral Order does occur in 

 "' * the floral leaves as well as in those 



of the stem ; it often ^happens, especially when the 

 organs are numerous, that they form spiral series; 



