434 



GENERAL BOTANY 



being composed of a pistil with two plumose stigmas, three 

 stamens, and two small rudimentary organs at the base of the 

 pistil, cajled lodicules. Each flower is usually surrounded by two 

 pairs of bracts. The outer bracts are called glumes; the inner 

 bracts are called the palet and the lemma. Botanists are almost 

 unanimous in regarding the flower of the grasses as a highly 

 modified form of monocotyledonous flower, like that of Trades- 

 cantia or the lily, in which the perianth is represented by the 

 rudimentary lodicules. The lodicules, where they are well devel- 

 oped, serve to open the glumes, palet, and lemma, so as to 



Glume 



Ovar 



Glume 



Flower 

 a 



Floral plan 



Flower of flower 



b c 



FIG. 281. Flower of the oat 

 a, &, two views of the flower and its parts ; c, ground plan of the flower 



expose the essential organs. Where the lodicules are not well 

 developed, the flowers remain closed. Cross-pollination, where 

 this occurs, is usually effected by the wind, the anthers being 

 attached to the filaments at the middle, so as to be readily 

 swayed to and fro for the scattering of pollen. In many of the 

 cereal grains, like wheat and oats, the opening of the flowers 

 and the act of pollination occur early in the day and are often 

 completed in a relatively short time. 



The fruit is the caryopsis, or grain, which is formed by a 

 union of the ovary wall with the seed coat, making a dry 

 indehiscent fruit. 



