[Chap. XXXII 



FLOWERS, FRUITS, AND SEEDS 



357 



The floral cup of the EngHsh walnut is still more complex. The pri- 

 mordia of bracts below the pistillate flower become united with those of 

 the floral organs, and by further development become the husk of the 

 mature fruit. The hard shell of the nut develops from the two-carpellate 

 ovulary; the "meat" within is an embryo surrounded by thin seed coats. 



The floral cups of some flowers, such as those of the cultivated shrub 

 pearl bush, abscise when the flower is mature and do not form a part of 

 the fruits. 



Flowers of grasses and sedges have nothing closely resembling a 

 calyx or a corolla; in them the stamens and pistils are enclosed by small 



Fig. 155. Spike and flower of wheat (Triticum vulgare) . The two floral bracts, 

 or glumes (lemma on the right and palet on the left), enclose three stamens and 

 a pistil with two plumose stigmas. At the base of the flower inside the glumes 

 are two minute scales, the lodicules, which are not evident in the above figure. 

 Courtesy of World Book Co. 



scales or bracts, which are usually green and are often referred to as 

 glumes (Fig. 155). 



Flowers composed of calyx, corolla, stamens, and pistils are referred 

 to as complete. They are said to be perfect if they have both stamens and 

 pistils, regardless of the presence or absence of calyx or corolla, because 

 stamens and pistils are the essential parts of flowers. Not infrequently 



