218 MARSH PLANTS 



The precise function of these false nectaries cannot, 

 however, be said to be fully understood, at present. 

 They may be additional allurements to flies — i.e., insect 

 advertisements — or they may constitute a sort of fence, 

 which forces the insect to enter the flower, and reach 

 the concealed honey in a particular way, which is 

 favourable to cross-pollination. 



The Alpine Louseworts. 



The Louseworts, genus Pedicularis (natural order 

 Scrophulariacese, the Foxglove family), are quite 

 characteristic plants in marshy places in the Alpine 

 zone. More than ten species occur, as opposed to two 

 in Britain, so the genus is a very successful one in 

 Alpine Switzerland. They are quite similar in build 

 to our British Louseworts, except Pedicularis verticil- 

 lata, Linn., in which the leaves aire whorled. The 

 flowers, as a rule, are, however, rather larger than 

 with us, and are either yellowish-red or reddish-black, 

 according to the species. 



The interesting point to notice about the Louse- 

 worts is that they are semiparasites. This peculiarity 

 they share with several other genera, nearly related 

 and belonging to the same section of the family, such 

 as Euphrasia, Eyebright; Melampyrum, Cow- wheat; 

 Rhinanthus, Rattle; and Bartsia — all common in 

 Alpine Switzerland. 



In temperate floras parasitic Flowering Plants are 

 rare, though they are common in the tropics. They 

 are plants which attach themselves to other living 



