ANATOMY OF VINCETOXICLM PALUSTRE. 303 



KOSTELETZKYA VIRGINIC'A (L.) A. (4r{iy. 



Ledfhi'Oixd and flat, bifacial, stellate-pubescent on l)(>th surfaces. 



Ejjide/Diis cells with iioiiundulate, thin walls, except above and 

 beh)\v the larger veins, wliere the cuticle is rather thick and layered; 

 stomata witli guard cells sliglitly proiiiin(^nt, more numerous on tlie 

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

 arms with thick, smooth cuticle, separate nearly or quite to the l)ase, 

 each from a narrow foot cell in the epidermal plane. 



Hypoderrtial colleiichyma strongly developed above and below the 

 larger veins. 



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

 ous small intercellular spaces; mucilage cavities distribut(Ml 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 ^at, rather thin, aijproximately isolateral. 



Epidermis: Cells with radial walls strongl}^ 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. 



Collencliyma none. 



Stereome none. 



Chlorenchyma homogeneous, not imlisadic. 



ViNCETOXicUM PALUSTRE (Pursh) .\. Gray.^ 



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. 



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



Collenchyma none. 



Stereome none. 



Chlorenchyma not palisadic, homogeneous through IIh' l«'af. bnl 

 the interior containing less chlorophyll. 



Cells contain iiKj masses of crystals (calcium oxalate) scattcicd in 

 the chlorenchj^ma. 



Stem: Epidermis as in the leaf. 



' Seutera inaritima Decsne. 



