272 



BOTANICAL GAZETTE 



[OCTOBER 



chymatous cells form the pith; a few rows of cells, part of them 

 fibrous, form the cortex. 



Arctostaphylos Uva-ursi. — A woody little plant trailing over the 

 ground. Leaf thick, smooth, evergreen; outer wall of epidermis of 

 both surfaces thick, cutinized; side walls plane, cutin sometimes 

 16 v> thick; upper epidermis sometimes divided periclinally; bundles 

 compactly developed, with fibers above and below; collenchyma 

 next the epidermis; palisade several rows of shorter cells or two 

 rows of longer; all mesophyll cells elongated perpendicularly to 



the surface; stomata sunken one-half 

 the depth of the epidermal cells. Stem 

 with xylem cylinder very woody; walls 

 of pith and medullary ray cells heavy; 

 cortex and phloem zones very narrow; 

 cork layer not strikingly thick but very 

 dense; 9 years* growth in a stem 4 mm. 



An erect 



thick 



in diameter. 



Juniperus communis ( 

 evergreen shrub. Leaf 

 vex on one side, concave on the other 

 which is the morphological upper side 

 and is most protected when the leaves 



Fig. 2. — Juniper its com- 

 munis: section of leaf. 



stem; stomata on 



this side at the 



cells, guard cells with thickened 



outer and side walls of 



ermis thick 



n-13/i with cuticle 3.2^; hypodermis 



heavy; resin duct on convex side. Stem with a 

 and heavy wood cylinder; 13 years' stem 4 mm 



cork thick. 

 Junip 



virginiana. — -A shrub or small tree. 



Leaf awl- 



shaped; outer wall of epidermis very heavy, 9.6 /*, cuticle 4.8 ^; 



hypodermal 



thickened 



stomata on upper plane surface, the 



protected side when the leaf is appressed. 



mass 



almost 



stem 4 . 5 mm 

 thick. 



h; n growth rings in a 

 rows of sclereids in the cortex; cork 



