THE FLORAL ENVELOPES. 103 



F 5 = 



S A 



P G 



the F standing for flower. 



In order to indicate cohesion a line or a bracket over the letters may 

 be used, and a similar line placed vertically by the side of the letter may 

 represent adhesion ; thus the formula 



r\ r\ 



F * S G 



F5 = r ^ 



| PA 



may be taken to represent the flower of a Primrose,, in which the five 

 sepals are coherent, the five petals likewise coherent, the five stamens 

 free among themselves, but superposed and adherent to the corolla, and 

 lastly the five carpels coherent one with the other. The spiral or verti- 

 cillate arrangements may also be indicated by similar devices, thus : 



would indicate a calyx of five sepals arranged spirally on the plan, a 

 corolla of five petals verticillate, an androecium of numerous stamens 

 arranged spirally, and a gynsecium or pistil of five coherent carpels, the 

 sign rv> indicating a spiral arrangement, and the sign oo always indicating 

 an indefinite number of parts or too many to be readily counted *. 



Sect. 8. THE FLORAL ENVELOPES OR PERIANTH. 



Calyx and Corolla. The floral envelopes of a typical flower 

 consist of two circles of organs, forming the calyx and corolla. 

 There is no fundamental difference between sepals and petals (the 

 organs which compose these circles) ; and the only general defini- 

 tion that can be given is, that the 

 outer circle (or, if only one circle 

 exists, that circle) is the calyx ; 

 the corolla consists of the second 

 circle (or sometimes of additional 

 circles) of foliar organs intervening 

 between the calyx and the stamens. 

 In some few cases the perianth or 

 floral envelopes are entirely want- 

 ing, as in many Aroids. 



The above definition of the calyx 

 is liable to exception in rare cases; 

 for in the Malvaceae, the Dipsacese, and some Rosacese the true calyx 



* For details relating to the morphology of the flower the student should con- 

 sult Eichler's 'Bluthendiagramme,' Sachs's Text-Book, and Masters'? 'Vegetable 

 Teratology.' Reference should also be made to the account of the principal natu- 

 ral orders in the following pages, wherein the general principles of morphology 

 are illustrated by reference to their particular application to different orders. 



