STEMS OP GRASSES. 



561 



of germination, is absorbed by that surface, and supplied by it 

 to the plumula and radicle, until they have attained sufficient 

 development to absorb and prepare nutriment for themselves, by 

 which time the store laid up in the albumen is exhausted. This 

 provision enables the germination of the seed to take place with 

 much greater rapidity, than we usually find in those which have 

 a separate albumen ; for in the latter, the surface by which the 

 young plant absorbs from it is much smaller, the cotyledon being 

 sent upwards around the young stem. 



736. In general, the true stems of Grasses are hidden, like 

 those of several other Endogenous tribes, as well as of Ferns, 

 beneath the earth; and the stalks which bear the organs of 

 fructification are not to be considered in this light. In the 

 Bamboos of tropical climates, however, the true stems elevate 

 themselves into the air, sometimes to the height of 50 or 60 or 

 even 100 feet, sending out lateral branches. The internal struc- 

 ture of the rhizoma of 

 the Grasses is strictly 

 Endogenous ; as is that 

 of the culms or hollow 

 stems, if examined at 

 the period of their first 

 development ; and their 

 subsequent hollowness 

 results merely from the 

 development of the 

 fibrous portion of their 

 structure, which forms 

 the exterior, faster than 

 the cellular parenchyma 

 increases to fill it. This 

 form of the stem is a 

 very beautiful illustra- 

 tion Of the mode in Fl ' m '"~ AGROSTIS CAPILLARIS. a, the bivalvular 

 one-flowered glume ; b, the same opened, showing the 

 which the greatest pOS- fl wer ; c, the flower taken out to show the leaves of 



sible strength may be the caly *' "* the tw ~ toi ; d ' the ""* 

 obtained with the least expenditure of material. (See MECHAN. 



