84 Henderson — Comparative Study of Pyrolaceae and 



The structure of the leaf of Sarcodes sanguinea, described 

 by Oliver (58), corresponds closely with the material examined 

 by the writer. Stalked glands, similar in appearance to those 

 on the flowering axis, appear on the margin of the leaves. The 

 epidermis consists of thin-walled hexagonal cells slightly longer 

 than broad. On transverse section, these appear as somewhat 

 oval cells, those of the lower epidermis being slightly smaller 

 than those of the upper. Both surfaces are covered with cuticle 

 and a thin layer of wax, that on the outer or lower surface being 

 slightly thicker than that on the upper. Stomata are absent. 

 The basal leaves have a smooth lower epidermis, no hairs being 

 present. Further up the flowering axis, the lower surface 

 shows beginnings of multicellular glands with a long multi- 

 cellular stalk and a club-shaped head. These become more 

 numerous on the bracts which subtend the flowers. The meso- 

 phyll is undifferentiated, except that the first layer of cells 

 beneath the epidermis is composed of cells similar to it. Below 

 this occur 17-18 layers of hexagonal, thin-walled, closely packed 

 cells. The transverse section of the leaf is the same throughout, 

 the bundles being all nearly equal in size. They are much 

 more reduced than in Moneses uniflora. Several xylem vessels 

 are present, but the main part of the bundle is made up of 

 phloem. 



The structure of the leaves of Monotropa hypopitys has been 

 described by Kamienski (39). The writer's material corre- 

 sponds closely with his description, except for the presence of 

 hairs, a fact which he does not mention. His material, however, 

 may have been M. hypopitys var. glabra. The epidermis con- 

 sists of narrow elongated cells on surface view, somewhat oval 

 on transverse section, with the outer wall cuticularized, ridged, 

 and with a thin layer of wax on the outside of the cuticle; Hairs 

 are present, few on the upper, numerous on the lower epidermis. 

 They are simple, unicellular outgrowths with small, wart-like 

 protuberances. Stomata are absent on the upper and very rare 

 on the lower epidermis. Solereder (73) mentions that they 

 are rare on the lower surface of the leaf, but all other writers 

 say they are absent. The writer found three to five on a scale. 

 The mesophyll consists of several layers of thin-walled, hexagonal 

 cells with no intercellular spaces. There is no differentiation 

 into palisade and spongy mesophyll. Several bundles almost 



