222 



MATOXIACEAE 



[CH. 



Ji 



The genus -Matonidium occurs in the Jurassic of Yorkshire (Seward, 

 Jurassic Catalogue, Vol. l). The genus Matonia has been traced back to the 

 Cretaceous Period. Krasser has stated that Matonidium Wiesneri from the 

 Cretaceous of Kronstadt (Moravia) is indistinguishable from J/^/^///rt/><f^/z;/rt/« 



itself 



Anatomy 



The adult rhizome of Matonia possesses one of the most complicated 

 solenostelic structures known among 

 Ferns: in the young stem, however, simpler 

 conditions are found which suggest how 

 the final structure was arrived at. In the 

 most complex rhizomes, which may be 

 about 8 mm. in diameter, three concentric 

 vascular rings are seen embedded in 

 parenchyma, each showing typical soleno- 

 stelic structure. The arrangement as seen 

 at a node, and the connections with the 

 leaf-trace, are represented diagrammati- 

 cally in Fig. 498, C: this drawing also 

 indicates that foliar gaps occur, and how 

 the leaf-trace is directly continuous with 

 the outer and the middle of the concentric 

 rings at the node. There may also be 

 connection with the innermost ring, but 

 this occurs at some little distance from the 

 actual node, and so it is not shown in the 

 drawing. The result is that the whole 

 vascular system is connected, but only at 

 intervals of its whole length; the paren- 

 chymatous tracts in which the cylinders 

 are embedded are also connected through 

 the leaf-gaps. 



The ontogeny suggests how this com- 

 plicated structure is related to what is 

 seen in other and simpler Ferns. The 

 young axis contains at first a slender 

 protostele: but this soon expands, and 

 a strand of phloem appears in the midst 

 of the xylem. This internal phloem ap- 

 pears to be a phloem-pocket decurrent from the axil of the next higher 

 leaf, but there is as yet no true leaf-gap. The stele soon widens into a soleno- 

 stele with internal endodermis and central parenchyma. Meanwhile at the 



Fig. 498. Drawings from wax models of 

 the stelar system of Matonia pcctinala. 



A, from a young stem showing a node. 



B, from an older stem, showing a node 

 seen from behind. C, still older node, 

 seen from in front. .4 x 25. j5 x 12. Cx 10. 

 (After Tansley and Lulham.) 



