170 



MONOCOTYLEDONS 



Sw.Sh. 



of sheathed rudimentary leaves pointing upwards — the plumule,— 

 and another structure pointing downward — the radicle. The 

 remaining part which encloses plumule and radicle and- adjoins" 

 the endosperm must morphologically be considered as the coty- 

 ledon, though in shape and function it is very different from the 

 cotyledons in the Gram. On account of its shield-like shape it 

 has heen called scutellum. 



If the seed is sown, it will be seen, as in the Gram, that the 

 rootlet of the embryo makes its appearance hrst. 

 But, whereas the root of the Gram elongates form- 

 ing a tap-root from which side-roots are thrown 

 off, the radicle of the young Paddy plant ceases 

 growing, and sends forth mimerous roots from small 

 slieaths at the base of the seed forming a bundle 

 of fibrous roots. Meanwhile the bud of the 

 plantlet grows upwards piercing the earth or 

 mud lying over it, with its spear-like point. 



Rice is sown in wet land. After a few days, 

 thin blades peep out of the muddy water. If 

 we pull up one of them, we still see the seed 

 hanging on the lower end of the young plant. 

 But the husks are now empty. The little Paddy 

 plant has used up the contents for feeding its 

 tiny roots and blades. From this we learn that 

 the mealy substance wdiicli filled the seed, must 

 be of the same importance to the young Rice 

 plant as the thick seed-lobes of the Pea seed 

 are to that plant. It is a deposit of notirisJiing 

 matter for tJie support of the yonuij plant in its 

 first stages of growth, and this food is absorbed 

 by the inner face of the cotyledon. 



It contains al)out 80 Vo of starch and 7" ,> of 



albuminoides (substances like the wliite of an egg). 



As these two stuffs constitute the essential parts 



of human food, we can understand why rice is so valuable to man. 



.3. Stem. — After some time tlic little plants, sown closely 



in small secd-l)cds, are taken u[) .ind phmted out again. If this 



Fig. 157. — Longi- 

 tudinal section of 



a Grass-culm. 

 (J. C. Full grown 

 and t. C. tender 

 part of an inter- 

 node. iV. Node. 

 Sh. Sheath of a 

 leaf. Sli.Sw. Swel- 

 ling of the leaf- 

 sheath above the 

 node. 



