Monotropaceae with Reference to Ericaceae 65 



In Chimaphila umbellata, the outline of the section is rounded 

 pentagonal. The epidermis is papillate, the cells having a 

 thick cuticle covered with wax. The epidermal cells and four 

 layers of the cortex beneath have rather heavy thickened walls, 

 so that this appears as a corky tissue. Inside this region are 

 about four more layers of rounded, thin-walled cortical cells, 

 and then the endodermis, a layer of narrow rectangular cells 

 with the radial walls thickened. Within this is a narrow zone 

 of phloem and a much wider one of wood. The material exam- 

 ined shows three annual rings. There are five groups of primary 

 bundles toward the interior. Innermost is the pith composed 

 of thin-walled rounded cells. These cells and those of the 

 cortex contain numerous conglomerate crystals and aggregate 

 starch grains. 



In C. maculata, the sections resemble closely those of C. 

 umbellata, except that the outline is rounded triangular; there 

 are not as many thick- walled layers of cortex; there are only 

 three groups of primary bundles present; and crystals are not 

 as numerous as in C. umbellata. 



In P. rotundifolia, the outline is rounded triangular; the 

 epidermis is not papillate, the cells being only slightly curved 

 outward ; only the two outer layers of the cortex are thickened ; 

 there are 7-9 layers of unmodified cortex; crystals appear to 

 be present in the cortex only. There are no distinguishable 

 groups of primary bundles; otherwise the section appears like 

 that of C. umbellata. 



In P. elliptica, the structure is almost exactly similar to that 

 of P. rotundifolia. 



The axis of Moneses uniflora is not as thick and woody as 

 those preceding. The outline is circular. The epidermal cells 

 are only slightly curved outward. They and the outermost 

 layer of the cortex are only slightly thickened but not nearly 

 as much as in Pyrola and Chimaphila. There are about six 

 layers of cortex in all. The endodermis resembles those of 

 the preceding. There is a small amount of phloem, one year's 

 growth of wood with four groups of primary bundles toward the 

 interior, and a small area of pith. Single and aggregate starch 

 grains are found in the cortex and pith, but there appear to be 

 no crystals present. 



The structure in Monotropa hypopitys is greatly simplified. 

 The section is circular and wider in diameter than in any of the 



