86 



SEED 



ing, the nucellus is being absorbed by them, and no trace of 

 it remains in the mature seed. In such cases the whole 

 of the seed within the testa represents the embryo-sac and its 

 contents. In some plants the nucellus is not entirely absorbed, 

 but persists and forms an endosperm-like layer within the 



ii6 



V 'e 'h 



Figs. 116-T18. — Vertical sections of seeds: /i = scar on seed; w = 

 micropyle ; /,^j= testa; e = endosperm ; /?«=perisperm ; co, ci?/ = cotyledon ; 

 ;i>/= plumule ; r = radicle. Fig. 116. — Wallflower. Fig. i-Lj.—Stellaria. 

 Fig. 118. — Iris. 



testa: this is termed the. perisperm — e.g. Stellaria (fig. 117). 

 The testa is formed by the growth and hardening of the 

 integument or integuments, and the micropyle of the seed 

 represents the micropyle of the ovule. The funicle or 

 stalk of the seed is identical with the funicle of the ovule. 

 The subjoined table represents the corresponding parts in the 

 ovule and seed : — 



Ovule 



Seed 



(a) The contents of the embryo-sac = Embryo and Endosperm. 



(b) Nucellus .... =Perisperm. 



(c) Integuments . . . = Testa. 



\d) Micropyle . . . = Micropyle. 

 («) Funicle . . . = Funicle. 



As examples of different types of seeds, the following may 

 be cited as occurring in both Monocotyledons and Dicoty- 

 ledons. 



(i.) No endosperm, no perisperm : Pea, Bean, Wallflower, 

 Mustard, Pear, Apple, Hazel, Oak, and Chestnut (figs, i, 116). 



