8 



Transactions. 



Cyathea. 



In the first few leaves the process is similar to that in 

 t Dicksonia, but then differences arise because the arc is perma- 

 nently broken into three. 



First Stage. (Leaf, total length, 2 in.) 

 («.) Pinna bundle, (b. ) Lower median bundle takes part in the process. 



.1 z 3 



Second Stage. (Leaf, total length, 10 in.) 



Then the two small bundles (c) and (d) approach and fuse. 



U 



O 



y 



u 



u 



a, 

 b 



{a.) Upper band in pinna, (b.) Lower band in pinna. 



A similar fusion is seen in Pteris incisa, Polypodium punctatum, 

 and Hypolepis distans. 



The third and final stage is similar to the second stage, but 

 the bundles are more numerous. 





(a.) Upper band, (b.) Lower band, (c.) Segments for pinna. 



Gwynne Yaughan suggests that the curved form of petiole 

 stele is primitive (Loxsoma) ; but this does not help us in deciding 

 affinities. The curved form is simply the most convenient as 

 regards strength and insertion of pinna-bundles. 



Roots. 



Similar in origin in the embryo and in later development, 

 and branching to the Polypodiacece. 



< Iften in Dicksonia in slender plants there is only one root 

 per leaf for eight or nine leaves. The first few roots hardly 

 branch at all. In Dicksonia in the slender diarch strand there 

 arc few protoxylem elements, but in Cyathea (fig. 32) they vary 



