SPERMATOPHYTA 



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tered leaves, and short branches of limited growth bearing a few leaves in 

 a cluster. The leaves are deciduous. They have a long petiole and a 

 broadly wedge-shaped lilade (Fig. 284). The blade is typically bilobed 

 but may be entire or each lobe may be partially divided into several nar- 



FiG. 284. Leaf blade of Ginkgo biloba, showing dichotomous venation, natural size. 



Fig. 285. Cross section of long stem ot Glnkyo biloba, showing small pith, thick vascular 

 cylinder, and thin cortex, X 15. 



row segments. The leaves are highly variable, even on the same tree. 

 They exhibit dichotomous venation. 



The stem of Ginkgo is an ectophloic siphonostele. The long stems have 

 a small pith, a thick vascular cylinder, and a thin cortex, as in the Conit- 



