292 



MONOCOTYLEDONES. 



of the 4 outer rows behave as in the Wheat, but those in the two central rows 

 always remain closed. The -flowers in the two central rows of H. distichuni 

 remain closed and fertilise themselves ; they open exceptionally, and may be 

 pollinated by the ^-flowers in the 4 lateral rows. H. hexastichum is cleisto- 

 gamic. Gats pollinate themselves. 



The ripe Grass-fruit, in some species of Bamboo, is a berry ; in some other 

 Grasses a nut with loosely lying seed, in some even a capsule, but otherwise a 

 "caryopsis." In some instances it is loosely enveloped by the pales (Oat), in 

 others firmly attached to these (Barley), and finally, in others, "naked," i.e. it 

 is entirely free from the pales (Wheat and Eye). On the ventral tide there is a 



FIG, 292. Barley grain : A sec- 

 tion through the skin (a-d) and the 

 most external part of the endo- 

 sperm ; Gl the " aleurore layer " ; 

 st starch-containing cells; B starch 

 grains. 



FIG. 293. Wheat- 

 grain germinating: g 

 the plumule; b the first 

 leaf succeeding the co- 

 tyledon ; r 1 the primary 

 root ; r 2 lateral root. 



FIG. 294. -Older seed- 

 ling of the Wheat : s the 

 second sheathing-leaf ; 

 I first foliage-leaf. 



groove (Fig. 288 F) on the anterior side (dorsal suture), which is turned towards 

 the inner pale, it is convex, and at the base on this side, inside the testa, lies the 

 embryo (Fig. 288 D). The apex of the fruit is often hairy (Fig. 293). The xkin 

 (Fig. 291, a) is formed by the pericarp and testa, and in some cases (Barley) the 

 pales- also form the outer portion. The endosperm (b) is large, and formed of 

 parenchymatous, starch-containing cells : aleurone (proteid) grains may also be 

 found among them. When the fctarch-grains and the aleurone-grains adhere 

 together the endosperm becomes " horny," but is " floury " when the starch- 

 grains lie loosely with air between them. In the most external region, just 

 beneath the skin, 1-several layers of nearly cubical cells (filled principally with 

 aleurone-grains and fat) are found, the aleurone-layer (Fig. 292). The embryo 

 (Fig. 291 c-d) contains large quantities of fatty oil ; the large shield- like structure, 

 attached to the embryo and turned inwards towards the endosperm (c), is the 

 cotyledon (scutellum) ; it remains enclosed in the seed during germination, and 



