MORPHOLOGY OF THE FKUIT AND SEED 273 



Monocotyledonous plants, which, in a similar manner, enclose 

 the young growing parts of the stem. 



In other monocotyledonous embryos the ditferent parts are 

 more manifest ; thus, in many Grasses, as, for instance, the 

 Oat {fig. 591), the cotyledon only partially encloses the plumule, 

 g, and radicle, r; and accordingly these parts may be readily 

 observed in a hollow space on its surface. 



A peculiar development of part of the cotyledon, called the 



Fig. 589. 



Fig. 591. 



Fig. 592. Fig. 593. 



Fig. 590. 



Fig, 589. Vertical section of the fruit of the Betel-nut Palm (.Areca Catechu), 

 c. Remains of perianth. /. Pericarp, p. Ruminated albumen of the seed. 



e. Embryo. Fig. 590. Embryo of the Lime-tree {Tilia europma). c, c. 



Cotyledons, each with five lobes arranged in a palmate manner, r. Radicle. 

 Fig. 591. Section of the fi-uit of the Oat. p. Plumule. /-. Radicle. 



s. Scutellum. Fig. 592. Germinating embryo of the Oat. r. Rootlets 



coming through sheaths, co. c. Cotyledon, g. Young stem. Fig. 593. 



Embryo of Trigloehin. r. Radicle. /. Slit corresponding to the plumule, 

 c. Cotyledon. 



scutellum [fig. 591, s), separates the embryo from the endosperm 

 in the seed of the Grasses. 



The inferior extremity of the radicle is usually rounded {fig. 

 693, r), and it is through this point that the rootlets, r, burst 

 in germination {fig. 592). The radicle is usually much shorter 

 than the cotyledon, and generally thicker and denser in its 

 structure ; but in some embryos it is as _long as the latter, or 

 even longer, in which case the embryo is called macropodous. 



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