470 



ERICALES 



forming the most characteristic features of the herbaceous flora. 

 Aquatics are of rare occurrence and but few tree forms appear; 

 notably the ash, persimmon, catalpa, paulownia, etc. Heath- 

 Hke shrubs, however, are widely distributed in northern regions. 

 The invasion of the tropics with its favorable conditions has led 

 to an enormous increase in some of the groups and the develop- 

 ment also of a great variety of woody plants, as trees and climbers. 

 150. Ericales, the Heath Order. — This order is the simplest of 

 the Sympetalae and includes a great variety of plants that are 

 largely northern in their distribution. Many are cultivated, as 

 the azaleas, rhododendrons and laurels (Kalmia), and others are 

 familiar plants of bogs and woods as the sweet-pepper bush 



Fig. 326. A simple form of the Ericales: A, the shin leaf {Pyrola) with 

 flower just opened. B, flower with part of perianth removed to show the 

 retention of the anthers by the petals. C, later stage of flowering. The 

 anthers have been released by the spreading of the petals and the flower 

 stalk has inclined so that the spores sprinkle down on the stigma. D, flower 

 in section, showing the relation of parts in autogamy. — After Kerner. 



(Clethra), wintergreen (Chimaphila), Labrador tea (Ledtim), 

 RJwdora, Leucothoe, rosemary (Andromeda), leather leaf (Cham- 

 aedaphne), arbutus (Epigaea), checkerberry (GauUheria), bear- 

 berry (Arctostaphylos), huckleberry (Gaylussacia) , blueberry 

 (Vaccinium), heather (Calluna), cranberry (Oxycoccus). The 

 flowers of the heaths are very characteristic and sharply dis- 



