DICOTYLEDONS 



139 



places, is only eaten by animals when the plant 

 is very young, but is refused afterwards, as also 

 is the Marsh Lousewort at all times. 



Yellow Rattle {Rhinanthus Crista-galU, Fig. 

 35). — This common para- 

 site on grass-roots is 

 easily known by its in- 

 flated calyx and yellow 

 corolla (see figure). 



This plant is refused 

 by cattle when dried in 

 hay. If the seeds are 

 ground up with corn they 

 impart a violet-brown 

 colour to the flour. This 

 is due to a property 

 called Rhinanthine. It 

 is not known whether this 

 principle has really poi- 

 sonous properties or not ; 

 but if so, it is probably only after prolonged usage. 



Cow-wheat {]\Ielampyrum pratense^ etc.). — We 

 have four native species of this plant. Like the 

 last they are parasitic upon grass-roots, and 

 blacken when dried. M. prateiise has yellow 

 flowers, but in M. arvense they are red. 



While green the field Cow-wheat is eaten by 

 all animals, and is considered as hastening cows 

 into milk. If the seeds be ground up with wheat, 



Fig. 35- 



Rhinanthus Crista-galli ; 

 Yellow Rattle. 



