CHAPTER IX 

 THE FLOBAL LEAVES 



PEEIANTH 



Of the floral leaves which, together with the receptacle, con- 

 stitute a flower, those which are inserted outside the stamens 

 and carpels compose the perianth. The perianth may be 

 clearly differentiated into sepals and petals, or all its leaves may 

 be alike. 



CALYX. 



The whole collection of sepals belonging to a single flower 

 constitutes the calyx. In its simplest condition the calyx con- 

 sists- of a whorl or spiral of separate, simple sepals (e.g. Butter- 

 cup, Poppy), which are attached to the receptacle usually by 

 relatively broad bases. The calyx is then said to be poly- 

 sepalous. Often, however, the sepals are combined to form 

 a more or less cup-like calyx (e.g. Pea, White Dead Nettle), and 

 are then described as being gamosepalous. Even when the 

 calyx is gamosepalous it is usually possible to ascertain the 

 number of sepals which comprise it, because from the rim of 

 the cup a corresponding number of free portions, lobes or 

 teeth, protrude. For example, the gamosepalous calyx of the 

 Dead Nettle has five long teeth, and consists of five sepals. 



The sepals may form a single whorl of two (e.g. Poppy) or 

 more (e.g. five in the Buttercup) members. Less frequently 

 the flower has more than one whorl of sepals, as in the Wall- 

 flower, in which the sepals form two whorls of two each. On 

 the other hand, the sepals may be arranged in a spiral manner. 



In the case of the flowers of many plants the calyx merely 

 serves to protect the inner parts of the flower whilst the latter 

 is in the bud-condition. When this protective function is no 

 longer called for, because the flower has opened, the sepals 

 may fold back, as in some Buttercups, or fall off, as in the 



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