1858 



A TEXTBOOK OF THEORETICAL BOTANY 



ERICALES 



The Ericales are Metachlamydeae in which the flowers are either 

 pentamerous or tetramerous, regular in form and hermaphrodite. The 

 stamens are generally free from the petals and both they and the petals are 

 inserted around the margin of a nectar-secreting disc. The petals are 

 usually united into a bell-shaped tube, but sometimes they are free. The 

 ovary is multilocular and either superior or slightly inferior. The placenta- 

 tion is axile and the ovules have a single integument. The seeds are small 

 but endospermic: the embryo is straight. The plants are usually shrubs or 

 small trees with leaves which are either thick and leathery or minute and 

 folded and decidedly xeromorphic in character. They occur mainly in 

 cool and temperate climates and are characteristically intolerant of lime in 

 the soil. 



There is a considerable degree of uniformity of opinion regarding the 

 families which should be included in this order. The chief difference of 

 opinion lies in the limits to be assigned to the Ericaceae. Wettstein and 

 Engler both recognize the family Pyrolaceae, which Hutchinson includes 

 in the Ericaceae, while the latter splits off the Vacciniaceae, which the 

 former writers regard as a sub-family of the Ericaceae. Hutchinson on the 

 other hand has followed Bentham and Hooker in recognizing the family 

 Monotropaceae, which includes those genera which are saprophytic in 

 habit. 



Fig. 1761. 



-Pyrola rot iimlif olio. 

 flowering plant. 



Habit of 



Fig. 1762. — Monotropa fiypopithys. 

 Colourless inflorescence 



emerging from ground under 

 Birch. 



