160 GROWTH AND WORK OF PLANTS 



walls bend backward so that a nearly circular pore is formed. 

 The pollen grains are nearly spherical, smooth, and quite firm. 

 As the anther dangles at the end of the filament, a slight jar, 

 which even a slight breeze would give it, sets the pollen grains 

 rolling out of the opening. They usually fall out in large num- 

 bers. They may fall directly on the silk of the ear of the same 

 stalk, or, as is more often the case, the wind carries them to the 

 silk of adjacent plants. The Wades of corn, and the ground of 

 a field, are often literally covered with pollen grains, so great is 

 the number. 



265. The sterile flower. The sterile flower, the one with 

 imperfect or no stamens, lies between the palea of the fertile 

 flower and the other large empty glume which covers the sterile 

 flower. If care is used in dissecting the sterile flower by spread- 

 ing it apart, two membranous bracts will be found. They are 

 somewhat shorter and narrower than the others. The one 

 lying next the empty glume is the flowering glume, while the 

 other is the palea, and it lies next the palea of the fertile flower. 

 Between these two membranous bracts, i.e., between the palea 

 and flowering glume of the sterile flower, may often be found 

 remnants of the stamens, sometimes rudiments only in the form 

 of slender threads, two or three of them. At other times fila- 

 ments and anthers are both formed, but the pollen is unformed 

 and imperfect. In many such cases the filament does not elon- 

 gate and the anthers do not emerge from the closed flower. In 

 a few cases the stamens are perfect and well formed. Such a 

 spikelet contains two fertile flowers. 



266. The pistillate inflorescence of Indian corn. This is 

 formed by a consolidation of several spikes into one body, known 

 as the " ear" of corn (fig. 118). The cob is formed by the consoli- 

 dation of the spikes, the flowers being borne in double rows alofig 

 the outer surface, so that there is always an even number of rows 

 of grains on an ear. The ears arise as branches at some of the 

 middle joints of the stem in the axils of the leaves. When young 

 they are covered by the leaf sheath, but at flowering time the end 

 appears above the sheath and projects for some distance. The 



