2U(i 



THE PLANT COVERING OF OCRACOKE ISLAND. 



Croton maritimtjs Walt. 



Leaf flat., bifacial, both surfaces densely covered with a gray, scale- 

 like pubescence. 

 Epidermis: Ventral, cells small, walls not undulate, thin; stomata 



very numerous, guard cells level with the epidermis, each stoma sur- 

 rounded by 4 epidermal cells, 

 of which 2 are differentiated 

 as crescent-shaped subsidiary 

 cells parallel with the guard 

 cells; hairs pericellular, stel- 

 late, consisting of a long cylin- 

 drical, stalk rising above the 

 surface and composed of many 

 smaU cells partly of subepi- 

 dermal origin, from the apical 

 cell of which radiate in a 

 nearly horizontal plane nu- 

 merous unicellular, sharp- 

 pointed arms with thick, 

 smooth cuticle, cohering near 

 a, ^ ~ their bases so as to form a shal- 



PlO. 44. Croton morth'miw-hair from dorsal leaf low Clip. Dorsal, similar ; CU- 

 surface. a, View from above; f>, cross section; En, .. , .... , . 



epidermis; p, palisade, scale 2-to. ticle thickened and granular 



underneath the large veins; 

 stomata about equally numerous; hairs (fig. 44) with less numerous 

 and thinner-walled arms. 



Hypoderm, none, except beneath the large veins, where several 

 layers of thin- walled collenchymatic tissue occur. 



Stereome, none. 



ChlorencJiyma: Palisade in one layer, compact, the cells elongated, 

 interrupted only by thick-walled, branching, sclerotic idioblasts; 

 pneumatic tissue of roundish cells. 



Ilex vomitoria Ait. 



Leaf evergreen, thick, shining and dark green above, bifacial. 



Epidermis: Ventral, cells rather high (but small in their diameter 

 parallel to the leaf -surf ace), the outer wall and cuticle much thick- 

 ened but not nearly so high as the cell lumen, radial walls rather 

 thin, undulate; cuticle smooth; stomata none; erect, short, stout, 

 pointed, often curved, prickle-like unicellular hairs with very thick 

 walls (lumen almost obliterated) and smooth cuticle along the mid- 

 vein. 1 Dorsal, cells smaller, thicker- walled (outer wall and cuticle 

 exceeding the cell lumen in height), the radial walls nearly straight, 

 porous; cuticle wrinkled; stomata very numerous, guard cells slightly 

 depressed; hairs, none. 



'This species is, therefore, an exception to the rule that evergreen leaves have 

 no hairs on the upper or ventral surface. (See Lalanne, p. 117.) 



