THE PROMISE OF THE PLANT THAT IS TO BE 481 



FIG. 502. FOLLICLES OF 

 (Pceonia). 



aqueous currents." Linaria cymbalaria 

 grows down the face of old walls, and 

 its capsule-stalks twist until the cap- 

 sule is brought to a chink, into which 

 it is thrust. Here, when the seeds are 

 ripe, the capsule opens and discharges 

 them under conditions favourable for 

 their germination. 



The siliqua consists of two carpels, 

 the exposed walls of which break away, 

 leaving the seeds attached to an up- 

 right central framework, the replum ; on which is 

 stretched a delicate membrane which forms the false 

 septum of the fruit. Siliquas are characteristic of the 

 Crucifers, and usually take a long, narrow form, as in 

 the "Wallflower (Cheiranthus cheiri) and Stock (Matthi- 

 ola, fig. 596). In the genus Lunaria, which includes 

 the well-known garden plant Honesty, the form is 

 broadly elliptical (fig. 602). The force and sudden- 

 ness with which the siliquas in some species of Cruci- 

 fers ny open, owing to the drying and contraction of 

 the walls, greatly facilitate the dispersion of the 



FIG. 593. LAKKSPUR 



( Delph inium gra ndi- 



florum). 



A cluster of follicles (usually 

 five) is produced by each flower. 



The siliquas of the so-called "Rose of Jericho ; ' 



(Anastatica hierochuntica, fig. 600) are of unusual form, 



and the whole plant at the time of fruiting exhibits 



phenomena which are exceedingly curious. Its bran- 

 ches, which are 

 ordinarily of a 

 spreading cha- 

 racter, curve 

 inwards when 



the fruits are ripe, and form a kind of 

 cage or trellis about the siliquas. This 

 position is maintained, and the siliquas 

 remain closed in a dry atmosphere, but 

 directly the air becomes moist, the 

 branches straighten out again, and the 

 siliquas open. The seeds are thus fully 

 exposed, and with the first rainfall are 

 washed out of the fruit-valves and dis- 

 persed over the land. 



FIG. 594. CATERPILLAK-PLANT (Scorpiu- Tlie gUfada differs in no essential 



rus vermiculata). . ... mi /. 



The fruit is a tw^ed legume. particulars from the siliqua. The former 



n13 



