FORMS AND GROWTH OF SEED 



99 



131. Inverted Seeds. But sometimes a flower turns 

 over on its stalk, like the snowdrop and harebell, and the 

 same thing often happens to a seed. This gives rise to 

 the inverted, or anatropous kind (Fig. 223). In this case, 

 which is due to certain peculiarities in the early growth of 

 the seed, the stalk does not remain separate like the stem 

 of a pendent flower, but coalesces more 

 or less completely with the coats, and 

 thus forms the rhaphe (Fig. 223), d. The 

 chalaza remains at the base, ch, which is 

 now by inversion at 

 the top; but as the 

 stalk, or rhaphe, is 

 adherent to the coats, 222 _ A pendulous 

 it can not break away flower, showing the 

 at the base, and inverted P si 

 hence, in anatropous seeds the hilum 

 and micropyle are brought close to- 

 gether, at the real apex of the seed. 

 The adherent stalk, or rhaphe, often 

 223. Diagram of an becomes reduced to a mere line or 



inverted or anatropous 



seed, showing the parts in groove, as we saw in the cotton and 



section: a, outer coat; b, castor bean or may disappear altO- 

 inner coat; c, nucleus; 



d, rhaphe; ch, chalaza; gether, but the chalaza can generally 

 be distinguished by a tendency of 

 the parts to cohere at that point. 

 Variations in these modes of attachment are shown in 

 Figures 225, 226. In the campylotropous or curved kind, 

 the seed is bent over during early growth into a circular or 

 kidney shape, so that the micropyle is brought into close 



m 



mkropyle 



t W_/ M^ / 



224 225 226 227 



224-227. Seeds (GRAY) : 224, orthotropous seed of buckwheat, c, hilum and 

 chalaza, / micropyle; 225, campylotropous seed of a chickweed, c, hiiuin and 

 chalaza, f, micropyle; 226, amphitropous seed of mallow, f, micropyle, h, hilum, 

 r, rhaphe, c, chalaza ; 227, anatropous seed of a violet, the parts lettered as in the last 



