UNEQUAL COTYLEDONS 



33 



be accidental. It is, however, normal, and is explained by the 

 peculiar form and arrangement of the embryo (fig. 65, B-D) 

 in the seed. The fruit is an achene of peculiar form ; it is 

 oblong-linear, subcuneate, and laterally compressed, bifid at 

 the apex, and crowned with 2-6 unequal, closely reflexed, 



FIG. 66. Coreopsis Atkinsoniana. A, longitudinal section of achene, x 10. 

 B, transverse section of achene, x 10. C, embryo, x 10. 



acute bristles, more or less hairy, one-celled, one-seeded, and 

 indehiscent. The seed is oblong-linear, and tapers somewhat, 

 conforming to the interior of the fruit. The embryo is large ; 

 the inner cotyledon is doubled on itself; the outer one is 

 also turned over at the end, and 

 wraps round the narrower one, 1 not 

 reaching, however, to the narrow 

 end of the seed : the terminal lobe 

 of the shorter and broader coty- 

 ledon is the part which is folded 

 over, and the lateral lobes, which 

 are much smaller in the embryo, 

 are also due to the fold, as shown 

 in fig. 65, B-D. 



In Coreopsis Atkinsoniana the 

 seeds are obovate, curved longitudinally, and compressed 

 dorso-ventrally, conforming to the interior of the fruit. The 

 embryo again is slightly bent, following the direction of the 

 seed. Consequently the one cotyledon occupies the inner, 



1 The narrow cotyledon is sometimes absent. 



FIG. 67. Coreopsis Atkinsoniana. 

 ng, x 10. 



