ANATOMY OF SAND-STRAND SPECIES. 285 



SPECIES OF THE SAND STRAND. 

 Panicum AMARUM Ell.^ 



Leaf bifacial, strongly involute when dry, midrib not prominent on 

 the dorsal surface and not much so on the ventral surface, shjillow 

 furrows (deepest each side of the midrib), with broad and rounded 

 intervening ridges on the ventral surface, corresponding to very 

 slight depressions on the dorsal surface. 



Epidermis: Ventral, similar to the dorsal, but willi iliinner outer 

 cell walls; stomata at each side of the group of 3 thick-\vall(Ml 1) uni- 

 form cells at the bottom of each furrow; hairs none. Dorsal with very 

 thick, porous outer cell walls, 1 or sometimes 2 short cells alternating 

 with long ones, except in the rows containing stomata; stomata lying 

 in the shallow furrows, with walls of the guard cells much thickened; 

 hairs none. 



Subepidermal stereome in large groups above and below the midrib, 

 that above separated from the hadrome by several layers of thickish- 

 walled, colorless parenchyma; smaller groups above and below the 

 other nerves; strongly developed in the margins. 



Chlorophyll tissue (palisade) arranged radially in a single layer 

 about each mestome bundle, almost completely encircling the smaller 

 nerves, interrupted above and below the larger ones, each 2 neighbor- 

 ing rows of palisade separated by a single layer of colorless paren- 

 chyma; chloroi)hyll likewise occurring in the cells of the parenchyma 

 sheath which adjoin the palisade. 



Mestome bundles surrounded each by a mestome sheath wliich, in 

 the larger veins, has all, or nearly all, of its cells with walls (especially 

 the inner) strongly thickened ; mestome sheath in turn surrounded 

 by a large celled i^arenchyma sheath; mestome parenchjnna in a single 

 layer of thick-walled cells sei^arating the hadrome from the leptome. 



MUHLENBERGIA FILIPE8 M. A. Curtis." 



Z/ea/(fig. 33)condui)licate without power to unfold, appearing as if 

 terete, slightly asymmetrical, margins almost meeting al)ove the mid- 

 nerve, and hence only the dorsal surface exposed. From ihe sliuhi 

 opening between the margins to the uiidrib extends a narrow iissui-e, 

 with lateral furrows between the larger nerves reaching more than 

 halfway to the dorsal surface of the leaf. The ridges al)ove the 

 mestome bundles between these furrows arc broad and rounded at 

 apex, except that of the midnerve, which is narrowed outward (hence 

 conical in cross section). On the dorsal (outer) surface are narrow, 



'The typical form of this species was not observed upon Ocracoke JslaTid. but 

 the leaf of var. mi)iiLs Vasey & Scribner, which was collected there, c-orrespon«ls 

 in every detail to that of the type. 



- Compare Volkens's figure and description of .lr/.s//f/</ t'///(//(t (Fl. vEi;ypt.,pp. 

 49, 150, t. 10, ff. 4 to 7). 



