PAST HISTORIES OF PLANT FAMILIES 



99 



few ferns, which can generally be distinguished from it 

 without difficulty) has leaves at all like these, so that it 



r 



Fig. 66. A, Tuft of Ginkgo Leaves, showing their " maidenhair "-like shape. B, Single 

 deeply-divided Leaf to be found on the same tree, usually on young branches. 



is particularly easy to identify the fossil remains, of which 

 there are many. 



The wood is compact and fine grained, the rings of 

 secondary tissue being developed from a normal cam- 

 bium as in the case of the higher 

 Gymnosperms, and the individual 

 tracheae have round bordered 

 pits. There are small male cones, 

 but the seeds are not borne in 

 cones. They develop on special 

 stalks on which are no scales, 

 but a small mass of tissue at the 

 base of the seed called the 

 "collar". Usually there are two 

 young ovules, of which often only 

 one ripens to a fleshy seed, though both may mature. 



The ripe seed reaches the size shown in the diagram, 

 and is orange coloured and very fleshy; within it is a 



Fig. 67. Ripe Stage of Ginkgo 

 Seeds attached to their Stalk. <:, 

 " Collar" of seed. 



