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TEXTBOOK OF BOTANY 



flowers are often regarded as something distinct from the rest of the 

 plant, as is shown by the very common advertisement, "Plants and 

 Flowers for Sale." Few people realize that about one-half of the species 

 of plants bear flowers. 



The variety in floral organs is probably greater than that in other 

 organs of plants. Many flowers are conspicuous, but others are quite in- 

 conspicuous and appear as aggregates of scales and bracts, as in grasses, 

 alders, poplars, and birches. Technically, even a young pine cone may be 

 regarded as a type of flower. Such cones, however, lack both sepals and 

 petals. Flowers vary in size from the nearly microscopic flower of Wolffia 

 to the "fleshy" flower of Rafflesia, nearly three feet in diameter. Although 

 nearly all colors and almost all conceivable blends and mixtures of 

 colors may be found in flowers, the most common are green, white, and 

 yellow. In the flora of Ohio, for example, the percentages of different 

 flower colors are approximatelyly 36 green, 21 white, 20 yellow, 15 blue 

 to purple, and 7.5 red to pink. Locally and seasonally one or another of 

 these flower colors may predominate in the landscape. 



The flower is a short stem bearing floral organs and its development 

 is similar in many respects to that of a branch from a vegetative bud. 



Stigma"] 



' Style I Pistil 



OvularyJ 



Sepal 

 Receptacle 

 Peduncle 



Fig. 151. Vertical section through a complete flower (Flax). Courtesy of World 



Book Co. 



Mounds of meristematic tissue are formed by cell division at the growing 

 tip of a stem or floral axis. From them the parts of the flower develop as 

 lateral structures, in much the same way as ordinary leaves develop from 

 similar mounds of tissue ( Fig. 140 ) . There is, however, little or no elonga- 

 tion of the internodes between the floral organs; consequently flowers 



