CHAPTER XI. 



THE FORMS OF FLORAL ORGANS. 



The Form of the Perianth — Gteneral Observations. — It 

 requires but a most cursory observation of flowers to notice 

 bow gi-eat is tbe variability in tbe forms of all tbeir organs ; 

 and tbe questions now before us are, bow tbese morpbological 

 characters are correlated to tbe one process of pollination in 

 order to secure tbe fertilisation of tbe flower, and bow this 

 infinite diversity of form bas arisen. 



]\Iost important differences in tbis respect follow from tbe 

 fact of flowers being regular or irregular, and, wlien adayjted 

 to insects, according as tbe boney is easily accessible or not. 

 Regular * flowers wben borne singly are almost always 

 terminal ; f and wben they are arranged in racemes, etc., 

 tbey eitber stand out erect at tbe ends of tbeir pedicels so as 

 to be readily approacbed at any point of their circumference, 

 as in tbe Wallflower, or else tbey are pendulous ; under wbicb 

 conditions, as a rule, no particular part is favoured by tbe 



* It is usual to speak of a flower as being regular or irregular ; but 

 the term should be, strictly speaking, confined to one whorl at a time ; 

 though when the corolla is irregular, the calyx and stamens are usually 

 somewhat irregular as well. 



t The central and terminal flowers of many plants which elsewhere 

 bear irregular flowers are often regular, as in Horse-chestnut, Pelargonium, 

 several of the Scrojphularinece, as Snapdragon, Linaria, Pentstemon, etc. 



