

1784 A TEXTBOOK OF THEORETICAL BOTANY 



distribution of the offspring. E. angustifoliutn 

 (Fig. 1675) is a characteristic plant of burnt 

 heaths, being one of the first plants to re- 

 appear after a fire, as likewise in coniferous 

 forests. In North America it is known as 

 Fire Weed. Similarly it was found to be 

 one of the earliest arrivals on those parts 

 of large cities which were wrecked as a re- 

 sult of bombing. 



The genus Jiissieua contains some fifty 

 species of marsh and aquatic plants in which 

 special aerating tissue is well developed. 

 Both in the stem and in the water roots the 

 stele is very small but a large lacunar cortex 

 or aerenchyma is developed. In J. repens 

 two kinds of roots may develop in plants 

 growing in water. The one type are ordin- 

 ary roots, the other type (Fig. 1676) grow 

 upwards until they reach the surface 

 and the bulk of the tissue consists of 



Fig. 1675. — Epilobium angiisti- 

 foliiim. Flowering shoot. 



Fig. ibjb.—jfussietia peruviana. A, Transverse section of aerial 

 root showing part of the stele and the aerenchymatous 

 cortex. B, J. repens. Transverse section of aerial root. 

 (A, after Schenck. B after Goebel.) 



