CHAPTER IX 
SEEDS 
Seeds are very variable in structure, so much so, in fact, 
that scarcely any two seeds have a similar structure. It is 
necessary, therefore, whén examining seeds, to compare the struc- 
ture of the seed under examination with authentic plates or 
with the section of a genuine seed. The layers of the seed 
are the spermoderm, perisperm, endosperm, and embryo. In 
some seeds the spermoderm forms the greater part of the seed; 
in others the perisperm is greatest in amount; in still others 
the cotyledons make up most of the seed, as in the mustards. 
The cells forming these different layers differ in form, structure, 
and number; therefore it is not difficult to distinguish, and to 
differentiate between the different seeds when viewed as a sec- 
tion or as a powder. Almond is studied because it has most of 
the layers and cells found in seeds. 
SPERMODERM 
The spermoderm is the thin, brown, granular-appearing 
skin of the almond. The layers of the spermoderm are the 
epidermis, the hypoderm, the middle layers, and the inner 
epidermis. 
The epidermis consists of radially elongated, thick-walled 
stone cells which occur alone or in groups of two or more, but 
seldom as a continuous layer. The upper or outer part of the 
stone cells is non-porous, but the inner walls are strongly porous 
(Plate 123, Fig. 1). 
The hypoderm. The cells forming the hypoderm are com- 
pressed, the wall structure is practically indistinguishable, and 
the whole mass is reddish brown (Plate 123, Fig. 2). 
Occurring in this brown layer are several vascular bundles 
(Plate 123, Fig. 3). , 
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