REPRODUCTION IN PLANTS 



263 



flowers are called pedicels, and the term peduncle is applied to the main 

 stem of the entire flower cluster. A peduncle is thus the stem of a solitary 

 flower or of an inflorescence, while a pedicel is the individual stem of a 

 flower that is a part of a cluster. The flower-bearing branch differs from 

 an ordinary foliage branch in important respects. It is often without 



jflyg 



onther 



receptacle 



sepal 

 petal 



ray flower 



carpel 



anther 

 filament 



receptacle 



corolla of 

 ray flower 



receptacle 



Fig. 17.9. Types of flowers. A, lily, a monocot (family Liliaeeae), showing flower parts in 

 threes, separate, and all arising separately from the receptacle, with ovary superior. All 

 the other flowers are dicots. B, cherry (family llosaceae), with sepals, petals and stamens 

 UDited at base to form a cup, but ovary free and superior. C, gooseberry (family Rosaceae), 

 with fused bases of sepals, petals, and stamens united to ovary wall, making the ovary 

 inferior. D, strawberry (family Rosaceae), with enlarged receptacle bearing many small, 

 separate pistillate carpels and scattered stamens. E, sunflower (family Compositae), with 

 a head composed of many separate flowers on a common receptacle, sterile ray flowers at 

 margin and fertile disk flowers in center. (Modified from Turtox chart, courtesy General 

 Biological Supply House, Inc.) 



recognizable leaves, though it may have green bracts at the bases of the 

 peduncles or pedicels. Most of its "leaves" have been transformed into 

 the flower parts, densely crowded together at the twig apex instead of 

 being separated by distinct internodes, as in foliage branches. Lastly, 

 in a flower-bearing branch, the meristem is entirely used up in making the 

 floral leaves, instead of forming a persistent growing point, as in an 

 ordinary branch. 



