302 THE PLANT COVERING OF OCRACOKE ISLAND. 



Sesuvium maritimum (Walt.) RS.P. 1 



Z/ea/ isolate ral, somewhat succulent. 



Epidermis cells with nonundulate, radial walls, the outer some- 

 what thickened, some of the cells much larger and probably serving 

 for water storage; cuticle smooth; stomata lying in all directions, 

 guard cells level with the epidermis, each stoma bordered by 3 to 

 (usually 4 or 5) undifferentiated epidermis cells; hairs none. 



Stereome none. 



CMorenchyma homogeneous and occupying the entire thickness of 

 the leaf, interrupted by large intercellular spaces, whicli lie beneath 

 the large (water-storage) epidermal cells. 



Mestome bundles with a small group of collenchyma on the leptome 

 side. 



Stem: Epidermis with cell walls, especially the outer, strongly 

 thickened. Stereome none. Collenchyma in small groups above the 

 leptome of the primary mestome bundles. Cells containing crystal 

 masses in the pith and a few in the cortex. 



Tissa marina (L.) Britton. 2 



Leaf isolateral, hemicylindric, furrowed, margins sparsely ciliate, 

 especially toward base. 



Epidermis with cells somewhat elongated parallel to the leaf axis, 

 the radial walls strongly undulate, the outer walls 

 slightly thickened; stomata always parallel to the 

 leaf axis, guard cells slightly prominent, lying usu- 

 ally between 2 ordinary epidermis cells and at right 

 angles to their dividing wall, but sometimes bordered 

 by 3 cells; hairs (on the margins) glandular (fig. 40), 

 capitate, with a 3 or 4 celled stalk. 

 ,. Mi ,, Tiss „ „„„. Stereome none. 

 ina— glandular hair Chlorenchy mia compact, its cells not elongated. 

 EkXm* marglD ' Colorless parenchyma (water tissue) constituting 



the interior mesophyll. 

 Mestome bundle of. the midvein small, lying deep in the water tissue, 

 with a small group of collenchyma outside the leptome. 



Stern; Epidermis with thick outer cell walls and wrinkled cuticle. 

 Outer cortex separated from the inner by an unbroken, 2-layered ring 

 of stereome, with cell walls (especially of the inner layer) compara- 

 tively thin. 



1 Sesuvium pentandrum Ell. — Compare Warming "s description and figure of 

 ,N. portulacastrum, Halofyt Studier. pp. 180, 211. 

 1 Spergularia saliua J. and C. Presl. 



