REPRODUCTION AND DISPERSAL 



825 



2. FLOWERS 



General characteristics of flowers. The parts of a representative 

 flower. Ecologically speaking, & 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. 1 In 

 a representative 

 flower the outermost 

 whorl of floral leaves 

 is known as the calyx, 

 the individual leaves 

 being termed sepals 

 (s,&,figs. 1136, 1137). 

 Next within this is the 



corolla, which may or 



, , FIG. 1136. An inflorescence of a syringa (Philadelphus), 



y due up s h owm g th e floral organs of a hypogynous, monoclinous, poly- 



of 



leaves, petalous flower; note the calyx with its individual sepals (-?) 

 s fp and the corolla with its individual petals (p), the calyx and 



separate 

 known as 



corolla together forming the perianth; note also the stamens, 

 C, IlgS. 1136, II37). eac h 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 (/) and four 

 together form the per- Sti 8 mas () J this inflorescence is a cyme, the terminal flower 



blossoming first. 



ianth. Next within 



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

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

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



1 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 r61e of gymnosperm and pteridophyte strobili is 

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

 be regarded as true flower-producing plants. 



