HISTOLOGY OF ROSA CAROLINA. 491 



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Palisade in two layers, the cells short, especially those of the second 

 layer, which is not sharply differentiated from the upper layers of the 

 quite compact pneumatic tissue. Clusters of crystals of calcium 

 oxalate in the palisade. 1 



CoUenchymatic hypoderm in one layer beneath the midvein. 



Stereome in a large group of very thick-walled cells below and 

 adjoining the leptomeof the midvein, separated from the hypodcrmal 

 collenehyma by rather thick-walled, colorless parenchyma; also a 

 smaller group of thinner- walled stereome on the hadrome side of the 

 bundle, separated from the ventral epidermis by parenchyma like 

 that below. All but the largest veins embedded in the mesophyll. 2 



DECUMARIA BARBARA L. 



Hygrophile Forest formation, climbing high. 



Leaf thin, bifacial. 



Epidermis: Ventral, cells large, thin-walled, the radial walls not 

 or but slightly undulate; cuticle but slightly thickened. Dorsal, 

 cells smaller, their radial walls strongly undulate. Stomata contined 

 to the dorsal surface, lying in all directions, level with the surface, 

 each bordered by four or live ordinary epidermis cells. Hairs only 

 on the lower surface, especially along the veins, long, pointed, with 

 rather thick, granular' 1 cuticle, unicellular, each surrounded by sev- 

 eral small radially arranged foot cells. 1 



Palisade in one layer. Pneumatic tissue open. Large cells, ex- 

 tended at right angles to the surface and containing raphides, in the 

 palisade. 



Hypodermal collenehyma above and especially below the larger 

 veins (seven or eight layers below the midvein)/' 



Rosa Carolina L. 



Cleared land (noncultural), Shrubby, and Hygrophile Forest forma- 

 tions. 



Leaves thin, bifacial, more or less glaucous beneath, the veins im- 

 pressed above, prominent beneath. 



Epidermis: Cells high on the ventral surface, lower and smaller 



1 Crystals of calcium oxalate aggregated into " macles '" in the pneumatic tissue 

 and in the parenchyma of the nerves: also in the palisade, where they occupy 

 cells that are " a little higher than the neighhoring ones and almost spherical." 

 (Thouvenin, loc. cit., 125.) 



9 Smaller veins embedded in the mesophyll, their strengthening tissue not "durch- 

 gehend'' (going through to the epidermis). (Hollein Bot. Centralbl., vol.53, p. 211, 

 1893.) 



:! Incrusted with CaCQ.,. (Holle, Bot. Centralbl., vol. 53, p. 166, 1893.) 



4 Exactly like the hairs on the leaf of PhUadelphus billardieri as figured by 

 Solereder, Syst. Anat., p. 358,/. 8 A. 



'■' Most of the cells of the outermost layer of the hypoderm and some in the suc- 

 ceeding layers contain tannin, as do the palisade cells and many of those of the 

 pneumatic tissue, according to Thouvenin, Ann. Sc. Nat. Bot., ser. 7, vol. 12, p. 98 



