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Colorado Agricultural College 
Fig. 3. Types of seeds as determined by the relative posi- 
tions of hilum and micropyle, and the presence or absence of 
a raphe. A. Atropous (Orthotropous.) B. Campylotropous. 
C. Amphitropous. D. Anatropous. (After A. Gray.) 
Opening in the coat of the ovule remains as a tiny, pit-like open- 
ing in the seed-coat known as the micropyle. 
Fig. 4. Pea seed showing external 
features sometimes referred to in 
describing seeds. 
Seed-coats may vary greatly in their external appearance ; 
they may be ridged, veined, pitted, reticulated, grooved, faceted, 
scaly and warty, or provided with certain structures such as a 
raphe (Fig. 4). A mature or ripened seed consists of: Embryo, 
