244 THE STORY OF PLANT LIFE 



insects, and the former is the method. A few male 

 flowers may rarely be found on the female plants. 

 Frequently male and female plants grow in different 

 areas. The pollen is dust-like, as in other anemo- 

 philous flowers. 



The capsule bursts open, scattering the seeds to a 

 distance. The outer layer of the pericarp is of soft 

 parenchyma. The inner layer is woody and made 

 up of three layers of cells. In the inner epidermis the 

 fibres are at half a right angle to the axis, the next 

 layer having radially elongated cells, and the third 

 layer has cells at right angles to those of the epidermis. 

 The valves open outwards. In the annual Mercury 

 the cells are not so numerous. 



Being a widespread plant Dog's Mercury is known 

 by several names, as Adder's-meat, Boggard-flower, 

 Bristol- Weed, Cheadle, Dog Mercury, Dog's Cole, 

 Kentish Balsam, Maiden Mercury, Wild Mercury, 

 Sapwort, Snake's Bit, Snake-weed, Town-weed. 



Dog's Mercury is acrid and poisonous. It yields 

 a purple dye. It has been boiled as a spinach. 

 Sheep have been poisoned by it, but when dried it is 

 not harmful. 



Mercurialis perennis. — The illustration {Fig. 6g) 

 shows the social habit of Dog's Mercury. Some of the 

 plants show the male flowers in axillary ^ long-stalked, 

 slender racemes. The leaves are seen tq be opposite, more 

 numerous above. 



