3oo 



PLANT LIFE. 



animation ; (3) upon the exterior, one or two integuments 

 more or less readily distinguishable from each other (figs. 

 343> 344, 345)- 



Fig. ^43. — Longitudinal section of fruit of black pepper, containing a single seed. />c, 

 pericarp, showing two layers (the outer unshaded, the inner shaded by radial lines); 

 sc, seed-coats ; em, embryo, surrounded by en, the endosperm ; p, perisperm. Mag- 

 nified about 5 diam. — After Baillon. 



Fig. 344.— Seed of pansy, entire and halved, the latter showing the straight embryo, 

 the endosperm (white and dotted), the seed-coats ; Wf, micropyle. Magnified about 

 10 diam. — After Baillon. 



409. Fruit. — The growth of the embryo 

 excites not only the tissues of the ovule to 

 further development, but also the sporophylls 

 (carpels) bearing the ovules, and not infre- 

 quently even more remote parts. The carpels 

 and their contents and adherent parts, when 

 fully developed, constitute the fruit. The car- 

 pels are then known as the pericarp. The 

 changes which the parts undergo are chiefly 

 of two sorts — an increase in size and an altera- 

 tion of texture. The increase in size requires 

 no special explanation. The carpels may be- 

 come dry at maturity, or may thicken and become soft and 

 fleshy, or even juicy. In accordance with these differences, 

 two sorts of fruits are recognized, namely, dry fruits and 

 fleshy fruits. Between these, however, there is no sharp line 

 of demarcation. 



410. Dry fruits. — If the pistil contain only one or two 



Fig. 345. — Seed 

 of pokeberry 

 ( Phytolacca 

 de c a ndra) , 

 halved ; show- 

 ing curved em- 

 bryo next the 

 two seed-coats 

 and nearly sur- 

 rounding the 

 endosperm . 

 Magn. about 10 

 diam. — After 

 Ba-'llon. 



