3 * 



EDITH SCHWARTZ CLEMENTS 



tains. As far as possible, plants bearing mature leaves were gath- 

 ered at the period of maximum flower or the formation of fruit. 

 Where present, both stem and rosette leaves were preserved for 

 purposes of comparison, but in the following study and classifica- 

 tion, stem leaves only are considered. The endemic species are 

 grouped into types according to the comparative histology of their 

 leaves, whereas polydemic species are considered separately with 

 reference to the changes in the leaves of the different habitat forms 

 of each species. In both cases the type species is carefully de- 

 scribed according to a certain formula. Among the endemic, 

 species this type is followed by a list of all species resembling the 

 type. The individual variations of these are also noted, though in 

 every case their resemblance to the type is greater than their varia- 

 tions from it. Descriptions have been made from the most typical 

 part of the section and in a place where the bundle is cut true. 

 The measurements are usually the average of varying cells, though 

 occasionally extremes are noted. Terms have been used according 

 to the following definitions : 

 Plants 



endemic occupying one habitat. 



polydemic occupying two or more habitats. 

 Leaves 



xerophyll the leaf of a xerophyte. 



mesophyll the leaf of a mesophyte. 



hydrophyll the leaf of a hydrophyte. 



isophotic (fffo?, equal, fo>?, ^wro?, TO light) with similar cells 

 throughout or at both surfaces. 



staurophyll (araupos, 6, an upright pale or stake, yvUov, TO, leaf) 

 an isophotic leaf composed of prolate cells. 



spongophyll (0-7:0^09, 6, sponge, etc.) an isophotic leaf com- 

 posed of sponge cells. 



diplophyll (dtidoo?, two- fold, etc.) an isophotic leaf with pro- 

 late cells next to either epidermis, and central sponge tissue. 



diphotic (dt- twice, etc.) differentiated into palisade and sponge 



tissue at the respective surfaces. 

 Cells 



prolate oblong cells in a vertical position. 



oblate oblong cells in a horizontal position. 



prolobate with vertical lobes (" armpalisade " of Haberlandt). 



oblobate with horizontal lobes. 



