REPRODUCTION 



189 



far greater range of structural diversity than the other organs of 

 the plant, and we therefore depend upon the flower very largely 

 for those characters which distinguish genera and families of 

 plants from one another. 





Fig. 102. — Diagrams of various types of flowers. The transverse diagrams 

 show the numbers of parts and the relations between the members of the same 

 circle of parts. The longitudinal diagrams show the relations between the 

 various circles. Receptacle dotted, petals and filaments outlined, and other 

 structures solid black. A and B, transverse and longitudinal diagrams of the 

 flower of the Stonecrop (Sedum). Sepals, petals, stamens and pistils are all free 

 from one another. They are all attached directly to the receptacle, or are 

 hypogynous. Each ovary is simple. C and D, Cherry (Prunus). The sepals 

 are united into a gamosepalous calyx but the 'petals and stamens are'all separate. 

 The corolla and the stamens are attached directly to the calyx, or are epiacpalous. 

 The ovary has but one chamber, in which are two ovules. 



In number, the circles may differ considerably. Among some 

 of the more primitive orders there are several separate pistils 

 (Fig. 102, A), but this part of the flower is more often single, 

 at least as far as its ovary is concerned, although from the num- 

 ber of stigmas or of chambers in the ovary we have reason to 



