INTRODUCTION TO TABLES 12 13 



(Wilder, in press c) 



Within interridge areas and between boundary layers cyclan- 

 thaceous laminae exhibit raphide sacs and, sometimes, also sty- 

 loid sacs and/ or sacs intermediate between raphide and styloid 

 sacs (Tables 12, 13). These crystal sacs normally lack chloro- 

 plasts, but at least sometimes contain leucoplasts and, appar- 

 ently, normal nuclei. In raphide sacs the raphides usually 

 comprise an orderly array, and are sometimes compound. Styloid 

 sacs occur in Evodianthusfunifer and all species studied of Sphae- 

 radenia and Stelestylis, but are less common among remaining 

 species of Carludovicoideae. In almost all species raphide and 

 styloid sacs tend to be oriented along paradermal planes; how- 

 ever, in E. funifer the styloid sacs normally lie in all directions 

 within the mesophyll. Scattered regions of periderm occur in 

 various species, apparently, because of wounding. I have devel- 

 oped a concept of boundary layers. A boundary layer separates 

 ordinary mesophyll tissue from another part of the plant. Cyclan- 

 thaceous laminae exhibit four types of boundary layers, viz., 

 hypodermis, bundle sheath, epithelium of mucilage cavities, and 

 laticifer sheath. All boundary layers exhibit significant features in 

 common, in addition to position, including aspects of intercellu- 

 lar spaces between their constituent cells, and chloroplast posi- 

 tion. In the adaxial hypodermis the shapes of hypodermal 

 parenchyma cells in surface view are very predictable. 



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