GINKGOALES 



195 



A short distance back from the root tip, the outer layers of cells 

 are suberized. and just within the suberized layers, tannin is very 

 abundant. Starch, as in most roots, is very abundant. 



Fig. 209.^ — Ginkgo biloba: part of one of the two strands in the petiole of the leaf; 

 CO, calcium oxalate crystals; s, sheath; pp, protophloem; p, phloem; c, cambium; :*;, xy- 

 lem; r, rays; px, protoxylem; X180. 



Within a millimeter of the tip, the endodermis can be distin- 

 guished, and the next layer of cells outside it have characteristic 

 ring thickenings. 



The mature root looks much like the mature stem, with annual 

 rings and with similar bordered pits. 



