ANATOMY OF VINCETOXICUM PALU8TRE. 303 



KOSTELETZKYA VIRGINICA (L.) A. (4ray. 



Leaf broad and flat, bifacial, stellate-pubescent on both surfaces. 



Epidermis cells with nonundulate, thin walls, except above and 

 below the larger veins, where the cuticle is rather thick and layered; 

 stomata with guard cells slightly prominent, more numerous on the 

 dorsal surface; hairs stellate, consisting of 5 to 8 acute unicellular 

 arms with thick, smooth cuticle, separate nearly or quite to the base, 

 each from a narrow foot cell in the epidermal plane. 



Hypodermal collenchyma strongly developed above and below the 

 larger veins. 



Chlorenchyma: Palisade 1 -layered; pneumatic tissue with numer- 

 ous small intercellular spaces; mucilage cavities distributed in the 

 chlorenchyma. 



Mestome bundles almost completely surrounded by a thin, inter- 

 rupted sheath of stereome, which is most strongly developed outside 

 the leptome. 



Ammania koehnei Britton. 



Leaf Hat, rather thin, approximately isolateral. 



Epidermis: Colls with radial walls strongly undulate; all the walls 

 thin, except above and below the larger veins, where the outer walls 

 are considerably thickened ; cuticle smooth; hairs none; stomata 

 chiefly parallel with the veins, but some irregular; guard cells slightly 

 prominent, each stoma bordered by usually 4 undifferentiated epi- 

 dermal cells. 



Collenchyma none. 



Stereome none. 



Chlorenchyma homogeneous, not palisadic. 



Vincetoxicum palustrk (Pursh) A. dray. 1 



Leaves narrow, sharply reflexed and hanging almost vertically, 

 imperfectly isolateral. 



Epidermis: Cell walls rather thick, not, undulate; cuticle wrinkled, 

 especially above and below the veins; stomata more numerous on the 

 ventral surface, level with the epidermis, each bordered by 4 or (more 

 often) 5 ordinary epidermis cells, generally parallel with the leaf 

 axis on the ventral surface, very irregularly disposed, often at right 

 angles to the axis on the dorsal surface; hairs none. 



Hypoderm a single, narrow layer, only above the midrib. 



Collenctiytna none. 



Stereome none. 



Chlorenchyma not palisadic, homogeneous through the leaf, but 

 the interior containing less chlorophyll. 



Cells containing masses of crystals (calcium oxalate) scattered in 

 the chlorenchyma. 



Sfevn: Epidermis as in the leaf. 



1 Seuiera maritvnia Decsne. 



