290 PHYLUAI XIV. AXTHOPHYTA 



Here the flower axis is globularly enlarged somewhat as 

 in the Buttercup, and this is covered likewise with many 

 spirally arranged carpels (megasporophylls). At the 

 base of this globular body of carpels the axis is flattened 

 out into a rim or collar, on the margin of which the 

 stamens grow in several whorls of 5 or 10 each. On 

 this margin there grow also the five rounded, white petals, 

 and the five pointed, green sepals, both series in whorls. 

 The development of the single ovules 

 and the production of the egg are 



(S^ 



<^=^ essentially the same as in the two 



n^P£<^ preceding examples. After fertiliza- 

 tion the zygote develops into an em- 

 FiG 164— Vertical plan ^ryo plant cousistiug of a small stem 

 pistu)!'^^"^ ^°""" ^'""^ with a root at one end and two rudi- 

 mentary leaves at the other. The 

 endosperm which appeared in abundance after fertili- 

 zation is here wholly absorbed by the growing embryo, 

 so that at maturity the seed contains a large embryo, 

 and no endosperm. 



528. While these changes are taking place in the seed 

 the carpel enlarges, and the inner layers of the ovary 

 cells thicken their walls into sclerenchyma, w^hile the 

 outer layers soften into a juicy flesh (parenchyma). The 

 ripe carpels are thus very small fruits consisting of a thin 

 flesh surrounding a tiny stone, which encloses a single 

 seed. The proper fruits of the Strawberry are these 

 small ripened carpels. When they fall to the ground the 

 contained seed germinates by pushing out the root of 

 the embryo, and since there is no remaining endosperm 

 this is quickly followed by the escape of the remainder 

 of the plant from seed and carpel, when it pushes its stem 

 and leaves into the light, becoming an independent plant 

 (sporophyte). 



