278 THE JOURNAL OF INDIAN BOTANY. 



The sfcomata are depressed and are either present only on the 

 upper surface or are more numerous on the upper surface. The 

 guard-cells are elevated arid are accompanied by subsidiary cells one 

 on either side. The veins are numerous and are enclosed in complete 

 or incomplete sheaths. The larger veins are vertically transcurrent 

 above and below by stereome bundles. The assimilatory tissue in the 

 leaf consists of complete girders of palisade cells round the smaller 

 veins and of arcs of palisade cells on sides of the vertically trans- 

 current veins. The spongy tissue is altogether absent. The veins 

 with the accompanying assimilatory tissue are sometimes separated 

 from one another by vertical strands of articulation tissue. 



The mechanical tissue in the leaf-blade occurs in the form of 

 I-girders the webs of which are formed by mixed or unmixed vascular 

 bundles of the veins. The margins especially when thay are bluntly 

 pointed are strengthened by large stereome bundles. The epidermis 

 of the axis consists of small cells with the outer walls greatly thick- 

 ened and silicified. The assimilatory tissue consists of palisade tissue 

 or of chlorenchyma ; it is absent in some members. The mechanical 

 tissue is represented by a stereome tube supplemented by isolated 

 sub-epidermal girders. 



Vascular bundles are of two sizes, the smaller ones being usually 

 embedded in stereome strands formed by the sub-epidermal girders 

 and by flanges of the stereome tube. Of the larger vascular bundles the 

 peripheral ones are usually apposed to the inner side of the stereome 

 tube and the rest are scattered in the medullary tissue. The 

 medullary tissue usually consists of thin-walled cells, which, in some 

 members, are filled with starch grains. 



FILICINAE 



Actiniopteris dichotoma Bedd. — Figs. 360, 361. A segment 

 of the frond : — Upper epidermis of sclerotic cells and accompanied by 

 sub-epidermal stone tissue. Lower epidermis of small tabular cells 

 with outer walls thickened and toothed, and with groups of stone- 

 cells intercalated amongst them below the stele- Stomata on the 

 lower surface and accompanied by ordinary epidermal cells. Assimila- 

 tory tissue consisting of chlorenchyma. Stele supported above and 

 below by epidermal stone-tissue. Hairs absent. 



Stipe : — Epidermal cells sclerosed except at the angular por- 

 tion, and accompanied by sub-epidermal stone-tissue. Cuticle tooth- 

 ed. Stomata in angular portion. Assimilatory tissue consisting of 

 chlorenchyma. Hairs long and unicellular. Stele in the centre. 



