148 Forest Club Annual 



(a) Crystal aggregates in soft bast. 



Quercus 



Castanea 



Salijc 



Populus 



(b) Crystal aggregates and single crystals in the soft 

 bast. 



Ostrya 

 Carpinus 



2. Crystal aggregates primarily in the soft bast and 

 single crystals in the sclerenchyma ; bast fibers want- 

 ing. 



Betula 

 Alnus 

 Fag us 



Most of the genera have very Droad pith rays, i. e. of 

 more than one row of cells; only Alnus, Castanea, Salix and 

 Populus have been composed of one row. 



In Fagus, Quercus, Ostrya, Carpinus, Liquidambar and 

 generally in Plat anus the walls of pith rays become sclerotic 

 where they adjoin sclerenchyma tissues; while in Betula, Alnus, 

 Castanea, Corylus, Salix and Populus they remain thin-walled. 

 Pith rays entirely separated from bast strands were found to 

 be sclerotic in Quercus, Fagus, and Platanus. 



In the genera which have pith rays of only one row of 

 cells, no crystals were observed. Crystals in large amounts 

 were found in the pith rays of Ostrya, Carpinus and Corylus; 

 small amounts in Quercus, Fagus, and PlantanuS] and only very 

 few were found in the rays of Betula, Castanea, Ulmus, Celtis, 

 Morus, and Liquidambar. 

 Key to the Genera: 

 A. Bast fibers wanting. 



1. Bast parenchyma largely changed into moderately 

 thickened stone cells, which, as well a,s wide partly 

 sclerotic pith rays, contain crystals. 



Platanus 



2. Scattered groups of very much thickened stone cells. 



(a) The sieve tube elements have a single wide pored 

 cross-plate. 



Fagus 



