428 



GERANIALES RHAMNALES 



part of the ovary becomes leathery. The juicy pulp, which en- 

 velops the seeds, is formed from hair-like structures that arise 

 on the inner side of the carpellary walls and by degrees entirely 

 fill them. The navel orange is a chance variation in which a 



FIG. 321. Flowers of the Geraniales and Rhamnales : A, inflorescence 

 of Geranium. B, nearly mature fruit consisting of five united carpels. C, 

 discharge of the seed. The carpels snap apart, owing to the tension set 

 up by the drying out of the tissues. D, section of pistil, showing the 

 ovules with micropyle directed upwards. E, flower of the grape (Vitis), 

 a common form of the Rhamnales ca, calyx, reduced to a rim ; c, corolla, 

 which opens at base and falls off as a cap; n, nectar glands within sta- 

 mens. Compare Sapindales. F, corolla free from the receptacle. G, 

 flower freed from corolla, ovary in section, showing micropyle pointing 

 down as in Sapindales. 



secondary receptacle, bearing compartments like the normal fruit, 

 is introduced. The original stock from which the navel oranges 

 grown in our country have been derived was obtained from 

 Brazil. 



The buckthorn order, Rhamnales, is very closely allied to the 

 Sapindales and includes such familiar plants as the buckthorn 



