GINGKO 209 



II. GINGKOALES 



Wood nonresinous, the tracheids of two kinds, interspersed. Wood paren- 

 chyma present and forming idioblasts containing sphere crystals. 



1. * GINGKO, KAMPF. PLATES 18 AND 19 



Transverse. Growth rings broad. The summer wood thin ; the structure 

 chiefly open throughout ; tracheids chiefly squarish and large, with 

 smaller, thicker-walled tracheids interspersed. Resin passages and resin 

 cells wholly wanting. Crystal-bearing idioblasts rather numerous. 



Radial. Medullary rays devoid of tracheids. Terminal walls of the ray cells 

 very thin and not pitted. Bordered pits in 1-2 series. Spiral tracheids 

 wholly wanting. 



Tangential. Fusiform rays wholly wanting. Ray cells rather broad and 

 thin-walled. 



1. G. biloba, Linn. 

 Maidenhair Tree. Salisbitria. Gingko. Jap. = Icho 



Transverse. Growth rings very broad, the summer wood very narrow and of 

 open structure, passing gradually into the spring wood. Spring wood 

 open, the tracheids large, squarish, very unequal, somewhat thin-walled, 

 with which are interspersed less numerous, much smaller, rounded, and 

 thick-walled tracheids. Idioblasts containing sphere crystals somewhat 

 numerous. Medullary rays prominent, slightly resinous, i cell broad, 

 distant 2-10, more rarely 15, rows of tracheids. 



Radial. Cells of the medullary rays conspicuously contracted at the ends, 

 locally somewhat resinous, equal to about 5-7 spring tracheids; the 

 upper and lower walls very thin and not pitted ; the terminal walls very 

 thin, not pitted or locally thickened, chiefly straight ; the lateral walls 

 with oval, bordered pits having a narrowly oval or oblong orifice, about 

 1-4, or, in the marginal cells, 7, per tracheid. Bordered pits very numer- 

 ous in the broader tracheids, where they are compressed vertically and 

 crowded in i row, or more generally in pairs, forming 2 compact series; 

 in the narrower tracheids few, round, distant, and often wanting. Pits 

 on the tangential walls of the summer tracheids numerous, large, and 

 open. Idioblasts round or oblong, i sphere crystal to each ; scattering 

 or often in vertical series. 



Tangential. Fusiform rays wholly wanting. Rays strictly i-seriate, low to 

 medium ; the cells rather broad, oval, thin-walled, somewhat variable. 

 Idioblasts oblong, in vertical series. 



Native of Japan, now widely distributed through cultivation in similar 

 climates. 



2. * * G. pusilla, Dn. 



Transverse. Growth rings obvious, the spring wood passing gradually into 

 the not strongly denned summer wood ; tracheids in regular radial 

 rows, very uniform, those of the spring wood about 22 x 21 p., the walls 

 5.3 fj., thick. Medullary rays very narrow. 



