170 THE STORY OF PLANT LIFE 



transferred by its means to its own stigma, but to 

 that of another plant on the next visit. The stigma 

 has a row of hairs on the margin which serve to 

 brush the pollen of a plant visited previously from 

 an insect visitor's head. 



The seeds of the Bladderwort, which are dispersed 

 when the capsule bursts irregularly, are borne away 

 by the current or fall to the bottom. 



Bladderwort is called Bladder-snout, Bladderwort, 

 and Hooded Water Milfoil. 



Utricularia vulgaris. — Fig. 4S shows the branches 

 bearing nutnerous much-divided leaves, with bladders on 

 short stalks at the base of the filamejitary segments. 



58. The Vervain Group. 



Although a large group the Order Verbenacese is 

 represented in the British Isles by only one species, 

 the Vervain. There are about seven hundred and 

 fifty species and sixty-seven genera. They are 

 mainly sub-tropical or tropical in range, found in 

 America, Asia, Africa. In this group are included 

 garden Verbenas, Lantana, Vitex. Some are lianes 

 as the last two. In some cases the plants are adapted 

 to dry conditions, and are provided with thorns. 



These plants are herbs, shrubs, or trees. The 

 leaves are usually opposite, occasionally alternate, or 

 in whorls. There are no stipules. The leaves are 

 entire or lobed. 



The inflorescence is a raceme or a cyme. If a 

 raceme it is a head or spike, with an involucre of 



