IQI2] 



STARR— ANATOMY OF DUNE PLANTS 



*73 



Hypericum Kalmianum (fig. 3). — A bushy shrub. Leaf re vo- 

 lute, thick, leathery; outer wall of epidermis 4.8 /*, cuticle 2.4 ^, 

 lower epidermal cells inclined to be papillate; double palisade; 

 stomata sunken the depth of the epidermis. Stem with vessels 

 large, fibers heavy, lumen small; pith small, cork thick; three 

 growth rings in a stem 3 mm. in diameter. 



Trees 



Pinus Banksiana. — Leaf shorter and thicker than in most pines; 

 walls of epidermis heavy; outer 8/*, cuticle 1.8 /*; hypodermis 

 also heavy; thickness of both increased at the edges of the leaf; 

 outer wall of endodermis thickened 

 and lignified ; mesophyll cells with 

 infoldings in the walls; stomata 

 deeply sunken, with an outer and 

 inner vestibule and with walls 3.2/* 

 thick ; two resin ducts. Stem with 

 small pith; woody cylinder large, 

 composed of a solid mass of tra- 

 cheids with very thick walls. 



Quercus velutina. — Small in 

 comparison with many oaks, and 

 of rather scrubby growth. Leaf 



Fig. 3. — Hypericum Kalmianum: 



having 



section of leaf. 



ma 



surface; sclerenclr 



above and below collenchymatous; 



papillate; outer wall of upper an 



midrib: cells 



mi 



thick 



I lower epidermis thickened, 

 Stem with pith star-shaped; vessels 

 lumen : medullary rays narrow, pith 



matous; an irregular band of fibers in the cortex. 



Summary of xero phytic characters 



The true dune plants have the following characteristics, which, 

 th the excention of thp rhanrtm of the. conductive svstem. are 



admitted 



Habit 



in 



Artemisia, Hudsonia, Juniperus communis, J. virginiana); low 



