292 



THE PLANT COVERING OF OCRACOKE ISLAND. 



Mestome bundles each inclosed by a mestome sheath (figs. 38, 39, 40) 

 which has small cells with equally thickened walls; parenchyma 

 sheath with large, thin-walled cells containing chlorophyll where they 

 adjoin the palisade; mestome parenchyma in a single layer sepa- 

 rating the hadrome from the leptome of the larger bundles; com- 

 panion cells of the sieve tubes with much thickened walls. 



..P 



Fig. 40.—C'hloris j^etraea— three small mestome bundles from the blade. (Letters as in fig. 39.) 

 In a the mestome sheath is thick- walled only on the leptome side; in 6 and c the thickening of 

 the mestome sheath is more distinct and begins to show also on the hadrome side. The sheath 

 is closed in all of these small bundles and is a true mestome sheath. Scale 560. 



Uniola paniculata L.^ 



Leaf rather thick and hard, more or less involute when dry, deeply 

 furrowed on the ventral surface, the intervening ridges broad and 

 truncate or but slightly rounded at summit; dorsal surface with very 

 slight corresponding depressions. 



Epidermis: Ventral with cells smaller and thinner-walled than on 

 the dorsal surface, the outer w^alls more arched, many of the cells, espe- 

 cially on the sides of the furrows, extended into short, stout, pointed, 

 unicellular, antrorse, prickle-like hairs with cuticle rough and exces- 

 sively thickened (lumen almost obliterated except toward the base) ; 

 stomata near the bottom of the ventral furrows; bulliform cells in very 

 small groups at the bottom of the furrows. Dorsal with conspicuously 

 pitted walls and ver^^ thick,^ strongl}^ wrinkled cuticle, 1 or sometimes 

 2 or 3 short cells alternating in the same rows with long ones ; hairs 

 none; stomata less numerous than on ventral surface. 



Stereome strongly developed (more so than in any other of these 

 strand grasses) ; strong, flattened subepidermal supports at the sum- 

 mits of the ventral ridges, separated from the mestome bundles by 

 thin-walled colorless parenchyma which also contains small, isolated 

 groups of stereome; narrow, mostly 2-layered subepidermal groups 

 on the dorsal side opposite the ventral furrows; strong subepidermal 

 supports on the dorsal side of each mestome bundle; finallj^, strong 

 marginal groups. 



Chlorenchyma: Palisade small-celled, radially disposed on each side 

 of each mestome bundle in single layers, which are perpendicular to 



' Compare Holm, Bot. Gaz. vol. 16, p/. 32, ff. 8 to 12, 1891. 



2 But much less so than in Holm's material from Fort Monroe, Va, 



