THE OLDER SPOROPHYTE 



195 



stipe and finally disappears entirely before the stem is reached. The s.clerenchyma 

 is also replaced by collenchyma in the rachis of the terminal divisions of the leaf. 

 Tannin sacs are quite absent except from the immediate vicinity of the bundles, 

 where they occur upon the inner concave side, either in direct contact with the bundle 

 or actually within it. The leaf lamina is only about half as thick as that of the leath- 

 ery leaf of Dancca elhptica, but shows much the same structure. The palisade cells 

 are not quite so well developed and there is a complete absence of sclerenchyma, but 

 otherwise the structure is very similar. The cells of the epidermis are undulate in 

 outline and the stomata, like those in Danaa, are surrounded by a series of accessory 

 cells. 



The large roots may attain a diameter of 6 to 7 millimeters. In the absence 

 of the hypodermal sheath of sclerenchyma they more nearly resemble Kaulfussia 

 than Danaa, but they are more like Dancea in the greater number of xylem rays, 

 which number twelve in the largest roots examined. In these later roots the central 

 part of the stele is occupied by the pith, the xylem rays not being united as they 



Fig. 177. 



A. Apex 'it .t small root oi Marattia douglasii, showing two initial cells. 



B. Transverse section of apex of .1 similar root. 



C. Longitudinal section of the apex of the second root. 



D. Apex of a large root of M. alala. x x, initial cells. X200. 



.in in the toots from the younger plant, but in some cases a few scattered tracheids 

 appear in the central region. There is usually a ring of conspicuous mucilage 

 ducts in the cortex, but these were sometimes not very well developed. Numerous 

 tannin sacs are scattered through the cortex and also occur within the stele. 



THE SPOROPHYTE OF ANGIOPTERIS. 



Angtoptcrts is the largest and most specialized of the Marattiacc.i . As we have 

 indicated before, there is much difference of opinion as to the number of species 

 which should be recognized and many botanists consider that all of the forms bel<>n» 

 to a single extremely variable species. Bitter, however, in his account of the Marat- 

 tiaceae in the "Naturliche Pflanzenfamilien," thinks that from 20 to 30 species 

 should be recognized, following in this respect the classification given by Presl and 

 l)e Vries; while Christensen (Christensen I) recognizes 62. I have examined ma- 

 terial from Australia furnished by Mr. J. H. Maiden, director of the Botanical 

 Gardens in Sydney, as well as material collected by myself in Ceylon and Java. 

 Some of the specimens growing in the Botanical Garden at Buitenzorg are the 

 largest that I have seen. Leaves 6 meters and upwards in length were measured and 

 the upright caudex was almost as big as a barrel. The specimens seen in Ceylon 

 were somewhat smaller. 



