CHAPTER XII 
THE FLOWER 
The FLower is a shoot which has undergone a series of 
changes so as to serve as a means for sexual reproduction. It 
represents a highly modified stem or branch which bears 
appendages. 
A TypicAL OR CoMPLETE FLOWER possesses four circles or 
whorls of floral leaves arranged upon a more or less shortened 
and frequently swollen upper end of a stem axis called a RECEP- 
TACLE, Torus or THALAMus. These whorls passing from periph- 
ery toward the center are: CALYx, composed of parts called 
sepals; CoROLLA, composed of parts termed petals; ANDRECIUM, 
composed of parts called stamens or microsporophylls; and 
GyNncciuM, composed of one or more parts termed carpels, pis- 
tils, or megasporophylls. In a complete flower the calyx and 
corolla constitute the perianth or floral envelope. 
The stem bearing the flower is called the flower stem or 
PEDUNCLE. 
The stamens and carpels constitute the EssENTIAL ORGANS, 
and a flower is said to be Perrect when these are present and 
functional. An ImpEerFecT FLower shows one set of essential 
organs wanting. The calyx, corolla and receptacle constitute 
the Accessory Orcans of the flower. 3 
A HERMAPHRODITE FLOWER is one which possesses both 
stamens and carpels which may or may not be functionally 
active. In some cases the stamens may alone be functional 
_ while in others the carpels only may function. 
A RecuULAR FLOWER possesses parts of each whorl of the 
same shape and size, as the flower of the buttercup. This kind of 
flower possesses radial symmetry and is also called for that 
reason ACTINOMORPHIC. : 
An IRREGULAR FLoweEr is one in which the parts of one or 
more whorls differ in shape and size. If it possesses bilateral 
symmetry, as the flower of the violet or sweet pea, it is also called 
262 
