THE ANGIOSPERMAE 



1533 



(i) Siliqua. A pod-like fruit formed of two carpels.* It is 

 generally regarded as a special type of the next class, the 

 capsules, but it has several points of distinction. The 

 form of the siliqua may be either long or short, cylindrical 

 as in Hesperis (Fig. 1395), or flattened as in Liinaria 



Fig. 1305- — Hesperis mntronalis. Dame's 

 Rocket. Long siliquas, constricted 

 between the seeds. 



(Honesty). When it is as broad as its length, or broader, 

 it is called a siliciila {Copsella, Thlaspi). It may be 

 flattened in either direction, that is either in the plane 

 of the carpel walls {Liinaria) in which case the carpels 

 themselves are broad and flat, or at right angles to this 

 plane [Capsella), when the carpels are narrow, but deeply 

 pouched. In Camelina the siliqua is globose. Most 

 siliquas contain a number of seeds, but a few have only 

 one seed in each carpel {Iberis, Biscutella) or only a 

 single seed (Isatis). 



The suture at the carpel edges marks the position of the placentae and 

 forms a thick rib which surrounds the fruit. From the suture on each 

 side of the fruit there grows inwards a longitudinal membrane and the two 

 membranes meet and overlap, forming a false septum and dividing the 



* Kerner and some other subsequent authors, especially Saunders, have maintained that 

 there are really four carpels involved. The two outer carpels being sterile and forming the 

 valves, while the marginal ribs represent two inner, reduced but fertile carpels. 



