PLANT ORGANS AND" ORGANISMS 183 



When the staminate and pistillate flowers are borne on different 

 plants of the same species, they are termed Dicecious, as the Sassafras 

 and Willow. When staminate, pistillate and hermaphrodite flowers 

 are all borne on one plant, as on the Maple trees, they are polygamous. 



Connation and Adnation. In the development of the flowers of 

 primitive species of flowering plants, the parts of each whorl are dis- 

 joined or separate from each other. In many higher types, however, 

 the parts of the same whorl frequently become partly or completely 

 united laterally. This condition is termed connation, coalescence, 

 cohesion or syngenesis. Illustrations of this may be seen in Bella- 

 donna, Stramonium and Uva Ursi flowers, where the petals have 

 joined laterally to form gamopetalous corollas. When the one or 

 more parts of different whorls are united, as of stamens with petals 

 (Rhammus] or stamens with carpels (Apocynum) the union is called 

 adnation or adhesion. 



The Receptacle. The Receptacle, Torus or Thalamus is a more or 

 less shortened axis (branch) which bears the floral leaves. It is 

 usually flat or convex, but may be conical and fleshy as in the Straw- 

 berry, concave as in the Rose and Fig or show a disc-like modifica- 

 tion as in the Orange. The internodes of the receptacle in many 

 species lengthen and separate various whorls. When the lengthen- 

 ing of the internode occurs between calyx and corolla, as in Lychnis, 

 the structure resulting is called an anthophore] if between corolla and 

 andrcecium as in Passiflora, a gonophore\ if betwen androcecium and 

 gyncecium as in Geum, a gynophore. If the flowers of the Umbel- 

 lifers the receptacle elongates between the carpels producing the 

 structure called a carpophore. 



The Perigone. The perigone or perianth is the floral envelope 

 consisting of calyx and corolla (when present). 



When both whorls, i.e., calyx and corolla, are present the flower is 

 said to be dichlamydeous; if only calyx is present, monochalmydeous . 



The Calyx. The Calyx is the outer whorl of modified leaves. Its 

 parts are called Sepals, and may be distinct (Chorisepalous, from a 

 Greek word meaning disjoined) or more or less united (Gamosep- 

 alous) . They are usually green f oliaceous or leaf -like but may 

 be brilliantly colored, hence the term petaloid (like the petals) is 

 applied. Examples: Tulip, Larkspur, Columbine and Aconite. 



