II] 



NUT 



17 



the remains of the stigmas above show them to be fruits. 

 The student can test this latter character easily by com- 

 paring the sweet-chestnut (a nut) with the horse-chestnut 



Fig. 14. Chestnut, Castanea vesca. 1, flowering shoot ; 2, vertical 

 section through cluster of female flowers in their involucre ; 3, transverse 

 section of ovary ; 4, a male flower ; 5, fruits in their involucre (Wo). 



(a seed), the prickly covering of the former being a cupule 

 and each chestnut having its withered stigmas above, 

 whereas in the horse-chestnut the prickly covering is the 

 true pericarp. 



A still commoner form of the Nut-type is the Achene, 

 which is normally a monocarpous, one-seeded, and usually 



w. iv. 2 



