COMPOSITE 



117 



thin, membranous ; hilum and micropyle inferior, contiguous ; 

 chalaza apical, superior. 



Endosperm absent. 



Embryo large, straight or slightly curved longitudinally, con- 

 forming to the interior of the seed, colourless ; cotyledons rotund- 



FIG. 460. Coreopsis Atkinsoniana, x 20. A, longitudinal section of 

 achene : E, embryo ; T, testa ; PC, pericarp ; B, radicle. B, trans- 

 verse section of achene : C, cotyledon ; PC, pericarp ; T, testa. 

 C, embryo, showing edges of cotyledons and their relative length to 

 the radicle. 



obovate, entire, plano-convex and closely applied face to face, lying 

 in the broader plane of the seed with their back towards the axis of 

 the receptacle or inflorescence, much longer than the very short, 

 turbinate, obtuse radicle at the base of the seed. 



Germination (fig. 461). 



The fruit splits vertically along each side, that is right and left 

 corresponding with the position of the 

 cotyledons in the broader plane of the 

 seed and fruit. 



The radicle emerges at its base and 

 fixes itself in the ground while the 

 cotyledons increase in size and escape 

 from the fruit. The cotyledons are 

 tinged with purple. 



When the fruit has been insufficiently 

 covered, it is often carried up by the 

 germinating embryo. 



The figure shows the seedling as 

 it appears three days after germination. The cotyledons are 

 broadly oval, obtuse, entire, narrowed at the base into a short 



FIG. 461. 

 Coreopsis Atkinsoniana, x 6. 



