20 BOTANICAL GAZETTE [JANUARY 



Salix sericea. Leaf: upper epidermal cells small, strongly 

 cuticularized; mesophyll compact, palisade of two layers of long 

 narrow cells; stomata on under surface, guard cells sunken beneath 

 the slightly protuberant companion cells; hypoderma of five- or 

 six- cell layers on hadrome side, and eight layers on leptome side of 

 midvein. Root: resinous bodies present in medullary rays and 

 cortex, the latter consisting of thick- walled cells; no mycorhiza. 



Ledum groenlandicum. Leaf: upper epidermis rugose, with 

 scattered unicellular hairs, margins strongly revolute, cuticle present, 

 cell walls thickened, the radial walls being broadly undulate; lower 

 epidermis covered with a thick cuticle and a felt of long multicellular 

 and short unicellular hairs, glandular hairs usually present near the 

 small veins, stomata protuberant; palisade of three or four layers 

 of broadly oblong cells; beneath vascular tissue of midvein and 

 between the mestome bundles occur large air cells which may form 

 lysigenic air cavities in the older leaves. Root: mycorhizal. 



Larix laricina. Lea]: bifacial, deciduous; epidermis thick- 

 walled, slightly cuticularized, guard cells sunken beneath the com- 

 panion cells; palisade tissue developed toward the dorsal surface, 

 two layers thick showing a radial tendency, stereome reduced to a 

 few cells beneath the leptome; two resin ducts near edges of leaf. 

 Root: composed of mycorhiza, resinous deposits throughout, cortical 

 tissues early destroyed by fungus. When grown in culture solutions 

 and well aerated, normal roots with root hairs are produced. 



Picea Mariana. Plants in bogs are stunted. Leaf: epidermal 

 cells thick- walled, cuticle present, guard cells sunk beneath the 

 companion cells; mesophyll cells compact, of a more or less radial 

 palisade type. Root: mycorhizal, resin deposits throughout, cortical 

 tissues destroyed by fungus. Normal roots are developed under 

 culture conditions. 



Pinus Strobus. Plants very much stunted in the bogs, leaves 

 shorter and thicker. Lea}, epidermal walls so greatly thickened 

 that scarcely a lumen remains, beneath this a hypodermal layer of 

 thick- walled cells; mesophyll cells compact and of the usual lobate 

 type. Root: mycorhizal, cortical tissues traversed by the fungus 

 hyphae; resinous deposits throughout. Stem: annual rings narrow 



