182 COMPOUND ORGANS OP PLANTS. 



The symmetry of the flower is frequently destroyed by the 

 abortion of one or more organs of the same verticil. In the 

 natural order Scrophulariacese we are able to follow, step by 

 step, the progressive abortion and final suppression of an organ 1 , 

 as for instance, a stamen, by examining the flowers of its dif- 

 ferent genera. Thus if we look at the flower of the common 

 mullein (Verbascum) which is placed at the head of the order, 

 we shall find that it is symmetrical and pentamerous although 

 somewhat irregular in its construction, having a calyx of five 

 sepals, a corolla of five petals soldered together, the lobes 

 broad, rounded, and a little unequal ; the stamens are five, and 

 alternate with the lobes of the corolla ; but one of the stamens 

 is a great deal less than the others ; it has proved already a 

 certain degree of arrest in its development. In Pentstemon 

 the anther is abortive, and the stamen appears in the form of 

 a bearded filament. In Linaria it may be detected in the 

 form of a little filament at the base of the superior lip of the 

 corolla. If now we examine a flower of the Scrophularia we 

 shall observe no more than four stamens. However, between 

 the two upper lobes of the corolla, on its interior surface we 

 shall find a little glandular scale, occupying the very place of 

 the missing stamen, and of which it is not difficult to recognise 

 the nature Lastly, if we open a flower of the Digitalis or 

 Antirrhinum, we shall find no trace of the fifth stamen, which 

 has completely disappeared. 



The abortion and suppression of the staminal verticil is 

 carried still further in other genera of the same family. Thus 

 Gratiola Virginica has a calyx of five sepals, five petals united 

 almost to their tips, and only two perfect stamens, the three 

 others having been entirely suppressed. But we can satisfy 

 ourselves that this abortion and ultimate suppression of the 



