288 



THE PLANT COVERING OF OCRACOKE ISLAND. 



Spartina patens (Ait.) Muhl.^ 



Leaf involute when dry, deeply furrowed between the nerves on 

 the ventral face, high, broad, rounded ridges separating the larger 



gle row of mestome parenchyma with cell walls thinner than vafiUpes and evenly 

 thickened; mestome parenchyma aJso in a single layer between hadrome and lep- 

 tome, and, with a few of the companion cells of the leptome, isolated or in groups 

 of 2 or 3, very thick- walled. 



(5) Muhlenhergia tricliopodes is a plant of low, often moist, pine barrens in the 

 Gulf strip of the Austroriparian area. The example here described was collected 

 in Mississippi. It is in several histological characters intermediate between capil- 

 laris ^-ndi filixjes, although morphologically the most distinct of the 8 species. 



Leaf conduplicate when dry, nearly flat when supplied with abundant moisture. 

 Ventral surface with only the 2 or 3 nerves nearest each margin prominent and 

 separated by deep furrows, the otliers, including the midnerve, barely i)rojecting. 

 Dorsal surface with narrow and rather deep furrows between the nerves. 



Epidermis: Ventral with sing'e rows of short cells alternating with several rows 

 of long ones; hairs, chiefly in the furrows, shorter, stouter, and thicker- walled than 

 iufilipes; bulliform cells much as in capillaris, rather thick- walled. Dorsal with 

 rather thick- walled cells (less so than in^Zipes), single, quadrangular (from above), 

 short ones alternating with longer ones; hairs short, stout, thick-walled, prickle-like. 



Suhepidermal stereome rather more strongly developed than in capillaris and 

 jilipes, in flattened supports above and below the mestome bundles (hence at 

 summit of the ventral ridges), strongest on the dorsal side, where it interrupts 

 the parenchyma sheath of the larger nerves: also in the margins. 



Clilorencliyma with cells as in filipes, radially arranged in single layers about 

 the bundles, entirely encircling the smaller ones, in the larger ones perpendicular 

 to the leaf surface and extending to the stereome at the summits of the ventral 

 ridges (as in Spartina strict a and Uniola panicidata)-, parenchyma sheath and 

 the large parenchyma cells above the mestome bundles also containing chlorophyll 

 where they adjoin the smaller-celled chlorenchyma. 



Colorless parenchyma (rather thick- walled) filling the interior of the ridges, and 

 in a single row of large cells between each 2 nerves, separating their respective 

 bands of chlorenchyma. 



Mestome bundles withont a true mestome sheath, but the larger ones surrounded 

 by a layer of mestome parenchyma which is much thicker-walled than in the 2 

 related species; around the smaller bundles the mestome parenchyma thinner- 

 walled and interrupted by 2 large vessels of the hadrome; mestome parenchyma 

 also in t layer between hadrome and leptome, as in the other 2 species. 



The important leaf characters of these allied species of Muhlenhergia may be 

 tabulated thus; 



[The sign x indicates presence of character.] 



' Compare the figure of S. versicolor in Duval- Jouve, Etude Anat., ^>/. lC,jhj. 



