360 



BOTANY 



fruit of the Angiosperms (Figs. 332-337) is extremely varied, and 

 may be either a dry fruit, like a grain of Wheat or the pod of a Lily, 

 or it may be a fleshy fruit, like the berry of a Currant, or the stone 

 fruit (Drupe) of a Cherry or Plum. Besides these true fruits, there 

 are various forms of spurious fruits, where the conspicuous part is 

 not the product of the carpels. Such are the Fig, where the edible 

 portion is the enlarged hollow stem, within whose cavity are born 

 numerous small flowers, producing one-seeded fruits. Similarly the 

 "seeds" of a Strawberry are really one-seeded fruits imbedded in 

 the fleshy receptacle or enlarged apex of the floral axis. The de- 

 velopment of edible fruits in the Angiosperms is connected with their 

 distribution by animals. 



Germination 



The germination of the seed is like that in the Gymnosperms. In 

 Angiosperms also, chlorophyll may be developed in the cotyledons 

 before they are withdrawn from the seed: Where the embryo fills 

 the seed, as in the Pea or Oak, the root quickly makes its way out 

 through the micropyle, and the second leaves, which are already 

 indicated in the embryo, soon unfold. The cotyledons may remain 



permanently within the seed, or 

 they may be withdrawn, and become 

 assimilating organs. When the em- 

 bryo in the ripe seed is small, it 

 grows for some time at the expense 

 of the endosperm before the root 

 pushes out of the seed. The cotyle- 

 dons are usually decidedly simpler 

 in structure than the leaves formed 

 later. 



The Stem 



The stem -apex in the Angio- 

 sperms never shows a single apical 

 cell, but the primary tissues are all 

 separated at the apex (Fig. 323). 

 The epidermis is continuous, and 

 below this is the primary cortical 

 tissue, the periblem, while the 

 central part is occupied by the 

 plerome-cylinder. It is not always 

 possible to separate the two latter 

 at the apex, but the dermatogen is 

 always clearly defined. 



FIG. 323. Naias flexilis, longitudinal 

 section through the stem-apex of 

 the young plant (X 250). 



