REPRODUCTION AND DISPERSAL 



825 



2. FLOWERS 



General characteristics of flowers. — The parts of a representative 

 flower. — Ecologically speaking, a. flower is an organ whose role is pol- 

 lination, which is the 

 initial process of seed 

 production. Struc- 

 turally, a flower is 

 a shortened shoot 

 with spore-bearing 

 organs, which usually 

 (though not neces- 

 sarily) are subtended 

 by one or more leaf- 

 like structures.' In 

 a representative 

 flower the outermost 

 whorl of floral leaves 

 is known as the calyx, 

 the individual leaves 

 being termed sepals 

 (5,^,figs. 1136,1137). 

 Next within this is the 

 corolla, which may or 



, , 1 Fig. 1 136. — An inflorescence of a S3n:inga (P/ji/ade/^/jMj), 



■' P showing the floral organs of a hypogynous, monoclinous, poly- 



of separate leaves, petalous flower; note the calyx with its individual sepals (i) 



known as -petals (p ^^"^ ^^^ corolla with its individual petals (p), the calyx and 



r A \ corolla together forming the perianth; note also the stamens, 



> 6 ■ -TIS^i ^^37)- each composed of a filament (/) and an anther (a), and the 



The calyx and corolla pistil, of which there are here to be seen the style (t) and four 



together form the Per- stigmas (g) ; this inflorescence is a cyme, the terminal flower 



,, -_ . , . blossoming first. 



tanth. Next withm 



the corolla are the stamens, each of which consists usually of a slender 

 stalk, the fllament (/, fig. 1136), and a spore-bearing body, the anther {a, 

 figs. 1136, 1137) , the spores being known as microspores (fig. 1145). At 



' The latter statement groups the strobilar organs of many pteridophytes with flowers, 

 there being no sharp line structurally between strobili and certain floral shoots or inflores- 

 cences (see p. 180) ; however, since the rdle of gymnosperm and pteridophyte strobili is 

 fundamentally different, in the following pages gymnosperms, but not pteridophytes, will 

 be regarded as true flower-producing plants. 



