PLANT ORGANS AND ORGANISMS 
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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 
androecium as in Passiflora, a gonophore; if between androecium and 
gynoecium as in Geum, a gynophore. If the flowers of the Umbel- 
liferce 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, monochlamydeous. 
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 — foliaceous or leaf-like — but may 
be brilliantly colored, hence the term petaloid (like the petals) is 
applied. Examples: Tulip, Larkspur, Columbine and Aconite. 
In a gamosepalous calyx, when the union of sepals is incomplete, 
the united portion is called the tube, the free portion, the limb, the 
orifice of the tube, the throat. 
In form the calyx may be regular or irregular; regular, if its parts 
are evenly developed, and irregular if its parts differ in size and shape. 
The more common forms are tubular, resembling a tube; rotate, or 
wheel-shape; campanulate, or bell-shaped; urceolate, or urn-shape; 
hypocrateriform, or salver-shape; bilabiate, or two-lipped; corres- 
ponding to the different forms of corolla, under which examples 
illustrating each will be given. 
The calyx usually remains after the corolla and stamens have 
