446 



GERANIALES— RHAMNALES 



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 

 secondary receptacle, bearing compartments like the normal fruit, 



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 (Vilis), a common form 

 of the Rhamnales — ca, calyx, reduced to a rim; c, corolla, which opens at 

 base and falls ofT as a cap; n, nectar glands within stamens. Compare Sapin- 

 dales. F, corolla free from the receptacle. G, flower freed from corolla, 

 ovary in section, showing micropyle pointing down as in Sapindales. 



is introduced. This never reaches very large dimensions and 

 may readily be seen at one end of the orange. 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 



