1534 A TEXTBOOK OF THEORETICAL BOTANY 



loculus of the carpel into two, with two rows of seeds on each side. When 

 ripe the carpel walls separate from the suture rib, beginning at the base, 

 and detach themselves upwards, finally falling off. The rib now forms a 

 frame to the exposed septum, the whole being called the replum, to which 

 the seeds remain attached. The seeds are often round and have no other 

 means of dispersal than rain-wash (see also Cardomine, p. 1508), but in 

 Lunaria and some other genera, the seeds are quite flat and can be blown 

 by the wind for short distances. Often the fruits do not dehisce until they 

 have been shed and in some forms {Iberis, Tfilaspi, Biscutella) the carpels || 



are winged and the whole fruit is blown about before the seeds are dropped. 

 The Woad plant, Isatis tinctoria, has one-seeded, indehiscent siliquas, 

 which are in fact samaras, and are similarly wind-dispersed. Other genera 

 having indehiscent siliquas are Biimas, Myagrum, Cramhe and Zilla. 



Where wind dispersal occurs, the fruiting pedicels lengthen consider- 

 ably, holding the fruits well out from the stem and fully exposed. The 

 whole infrutescence may be detached either before or after dehiscence of 

 the fruits, and the papery membranes of the replums then act as sails and 

 the infrutescence is blown about like a tumble-weed, shedding its seeds 

 broadcast. 



Sihquas in all varieties are the characteristic fruits of the Cruciferae and 

 occur also in a few of the Papaveraceae. 



(ii) Capsule. A many-seeded dry fruit composed of two or 

 more carpels, which dehisces in various ways to release 

 the seeds. In general the dehiscence starts at the apex 

 and the separated portions or valves do not become 

 detached. 



This is a very wide category and includes fruits of the most diverse 

 forms. They are classified according to the mode of dehiscence (Fig. 1396). 



Fig. 1396. — Diagrams of capsular dehiscence. 

 A and D, Loculicidal. B and C, Septicidal. 



