488 BOTANICAL SURVEY OF DISMAL SWAMP REGION. 



every four stomata). 1 Hairs confined to the impressed veins of the 

 upper surface and to the margins of the petiole, scattered, short, 

 conical, blunt-pointed, four or live celled. 



Palisade in two layers of short, broad cells, the inner less compact. 2 

 Pneumatic tissue from five to six layers, very open, with large air 

 spaces. 



ITypodermal collenchijina in several layers beneath the mid vein 

 and in the margins. 



Stereome none. 



Small groups of colorless parenchyma with small, thick ish- walled 

 cells occur above and below the mcstome of the larger veins. 



Magnolia Virginian a L. 



Abundant in the llygrophile Forest formation. 



Leaf coriaceous, senupersistent (deciduous farther north, more per- 

 sistent farther south), bifacial, dark green above, very glaucous 

 beneath, densely pubescent when young, veins numerous, reticulated, 

 prominent on the lower surface. 



Epidermis: Ventral, cells low, considerably greater in the dimen- 

 sion parallel to than at right angles to the leaf surface, their walls 

 straight or but slightly undulate; cuticle somewhat thickened. Dor- 

 sal, cuticle coated with granular wax. St omata none on the ventral 

 surface, lying in all directions on the dorsal surface, slightly sunken, 

 each accompanied by two subsidiary cells. 3 Hairs numerous on the 

 young leaves, more or less persistent along the veins, especially beneath, 

 long, slender, sharp-pointed, with smooth cuticle, bicellular, the ter- 

 minal cell much the longer. 1 



Hypoderm present- on the ventral face above the large veins, its 

 cells tabular, considerably larger than those of the epidermis, their 

 walls rather thick. 5 



'The presence of secretion cells in the epidermis is characteristic of most Aris- 

 tolochiaceae (Solereder, loc. cit., p. 414; see also below, p. 500, foot note 1). In 

 some species the walls of the secretion cells are suberized (Solereder, loc. cit., p. 

 417). In all Aristolochiaceae examined by Solereder the secretion was found to 

 contain ethereal oil, although otherwise differing somewhat in different species 

 (loc. cit., p. 419). In A. virginieum the secretion cells, found only in the lower 

 epidermis, are of two kinds— large spherical or ellipsoidal cells 0.015 to 0.0C mm. 

 in diameter, and smaller cells hardly distinguishable in size and shape from the 

 ordinary epidermis cells (Solereder, loc. cit.. pp. -42:1-4124). 



Solereder describes Auarum virginieum as having three layers of palisade. The 

 number probably varies. Even with the aid of the polarizer he failed to detect in 

 the mesophyll crystals such as are abundant in A. arifuiiiuii and other species 

 (loc. cit., pp. 423-424). 



3 A character of the Magnoliaceae. See Vesquc in Nouv. Archiv. Mus., aer. 2, 

 vol. 4. pp. 34, 35. 



'Although the disproportion is less than in the hair of the M. coiixpicua figured 

 by Vesque. (Loc. cit., t. ;.',/. 34.) 



'■• Lalanne (Feuilles persistantes, p. 7S>) describes a similar hypoderm occurring in 

 the leaves of M. gratulijlora, but apparently not confined to the neighborhood of 

 the larger veins. 



