272 Eduard Riibel 



occurs in the undergrowth. Of evergreens I noted, for example, 

 Gaidtheria shallon, Linnaea americana, Berberis nervosa, Viola 

 semper vir ens, Chimaphila umbellata, Vaccinium par vi folium, 

 and Pyrola bracteata. I should like to know whether the western 

 coast of Canada and Alaska have such forests, with ecology and 

 sociology to rank them among Laurisilvae. An ardent desire for 

 studies! Near San Francisco is the Sequoietum semper virentis 

 in the coastal mountains where cold sea-winds produce a fog 

 belt for the greater part of summer. The redwood spreads glossy 

 needle twigs, causing reflexes like regular laurel leaves; more 

 so does Arbutus menziesii. There occurs also an azalea. Rhodo- 

 dendron occidental, the laurel-leaved shrub Berberis nervosa, 

 and the low winter green, Gaultheria shallon. South America's 

 Araucaria forests belong also to this class of formation. 



^.Laurifruticeta: Laurel-leaved scrub. — This is the same as 

 Laurisilvae, but scrub instead of forest. In the oceanic southern 

 hemisphere this glossy-foliaged scrub occurs upward to the 

 wood limit, forming, as in South America, a scrub belt above 

 the forest. The same is done in the Caucasus by the association 

 of Rhododendron caucasicum. On the whole, such scrubs are 

 not so independent in the northern hemisphere, but for the 

 most part are biotically influenced, or, in a cooler climate, they 

 take refuge as underwood in forests whose dominants belong to 

 a climatically cooler type, yet create under their canopy a locally 

 more favorable climate. This telescoping of types presents a com- 

 plication. To be cited are the true laurel scrub Lauretum nobilis 

 in the Mediterranean, the Prunetum laurocerasi, and Rhododen- 

 dretum pontici in the Caucasus. 



5. Durisilvae: Sclerophyllous forests. — The dominants inDuri- 

 silvae are trees with sclerophyllous foliage or green axes function- 

 ing as leaves. Sclerophyllous leaves are evergreen, mechanically 



