290 



THE PLANT COVERING OF OCRACOKE ISLAND. 



form cells. Dorsal as in S. patens, the short cells iisuall}' single, 

 here and there rounded, with strongly thickened walls, almost form- 

 ing papillae; stomata none; hairs none. 



Hypoclermial colorless parenchyma in a single la^^er beneath the 

 dorsal epidermis,^ interrupted hy subepidermal stereome. 



Stereome not strongly developed, a small subepidermal group on 

 the dorsal side of each mestome bundle; flattened supporting strands 

 (1 or 2 la^^ers) at the summit of each ventral ridge, not decurrent 

 along its sides; also in the leaf margins. 



ChloreiicJiyma consisting of small palisade cells in a single laj^er, 

 radially arranged on each side of each mestome bundle and extend- 

 ing immediately beneath the epidermis to the stereome at the summit 

 of each ventral ridge ; each 2 neighboring laA^ers of palisade, between 

 each two nerves, either adjoining or separated by a few, large, color- 

 less iDarenchyma cells; chlorophyll also in most of the cells of the 

 parenchyma sheath. 



Mestome bundles with mestome sheath and mestome parenchyma 

 much as in S. p)atens. Parenchyma sheath (around the mestome 

 sheath) of large cells, those adjoining the palisade laj^er containing 

 chloroi)hyll, the sheath occasionally interrupted on the dorsal side of 



the bundle by a few 

 cells of the subepider- 

 mal stereome. Large 

 parenchj^ma cells, in 2 

 or 3 laj^ers, occup3dng 

 the thickness of the 

 ventral ridges and ap- 

 pearing to be an exten- 

 sion of the paren- 

 chyma sheath; when 

 in 3 layers, the middle 

 one colorless.^ 



YiQ.^l.—Chloris 2^etraea—\ea,f. blade. Transverse section. show- 

 ing the midrib in the keel, covered by layers of colorless tis- 

 sue and a group of buUiform cells (BC) on the ventral sur- 

 face; be, a small group of bulliform cells between two mestome 

 bundles. The mestome bundles are indicated by their paren- 

 chyma sheaths and by the stereome, which forms small sub- 

 epidermal groups. The thick walled mestome sheath is drawn 

 only in the two large bundles. Scale 84. 



Chlorispetraea Sw.^ 



Leaf (fig. 37) becom- 

 ing conduplicate AAiien 



^The specimen figured by Duval-Jouve. loc.cit., ha.s 3 or 3 layers. 



'-Spartina stricfa mariiima (Walt.) Scribn., the common form elsewhere along 

 our Atlantic coast, is prat^tically identical in leaf anatomy with S. strictd from 

 Ocracoke, except in the following particulars: The epidermis cell walls on the 

 dorsal surface are thinner and less porous and show less of the wavy thicken- 

 ing: the short cells are more often in pairs, and, when single, are more often 

 papilliform; stereome is somewhat more strongly developed, as would be expected 

 from the larger size of the plant and the greater length of the leaves. The mate- 

 rial examined was from Lynnhaven Bay, Virginia. 



'Figured by Duval-Jouve, Histotaxie, p. 35o, pi. IS, f. 1. For an example of 

 similar leaf structure compare the same nuthor's paper. "Etude histotaxifjue des 

 Cyperus de France," Mem. de I'Acad. de Montpellier, tome 1 pL 22, f. 6. 1874, 



