244 MR. A. C. SEWARD AND MISS S. 0. FORD ON 
petioles and roots. The patch of sclerous tissue lying in the angle made by an outgoing 
leaf-trace with the main stele (text-fig. 1, s/), from which it passes up in an obliquely 
ascending direction, is characterized by the unusual thickness of the walls and the almost 
complete obliteration of the cell-Iumen ; this increased strength of the supporting tissue 
in the axil of a lateral member where a break might easily occur is a common 
phenomenon among plants. The xylem of the stele forms a sinuous band made up of 
Text-figs. 1 & 2. 
| 
\ 
| 
wra 
oar 
not more than 7-8 and not less than 2 tracheal st 
? rands separated b j 
3-4 cells in breadth (text-figs. 1 & 2). esas ilu ias iua s 
The greater continuity of the xyl d 
3 | ylem and the 
s diea of medullary rays form one of the characteristic features of this stem 
"s Sec sem with that of Osmunda, in which the medullary rays are more numerous. 
| eg | a Së Strands vary from oval or horseshoe-shaped groups to continuous 
