I 



IOWA ACADEMY OF SCIENCES. 155' 



(m) of the second type cormecting these bundles with the 

 stereome. 



SPOROBOLUS VAGINAEFLORUS. 



In this species the epidermis (e) resembles that of other 

 species except the cuticle (c) which is much more fully devel- 

 oped. 



The bulliform cells (b) in this species differ much from those 

 of other species, they are very irregular in outline, the cells 

 ranging in number from eight to ten, and occur almost the 

 entire length of the leaf except near the sides where we find 

 the uncolored parenchyma (p). 



The carene (c') consists of one mestome bundle which has 

 stereome in contact with leptome (1). This is the only bundle 

 which is open. On either side of this median bundle there 

 are three or four small closed bundles. The leptome and had- 

 rome (h) are separated by thick walled parenchyma. The 

 mestome bundles number twelve, five to the left and six to the 

 right of the carene. The bundles are of two types: first the 

 median one which is open below and the second, closed; 

 the bundles of this latter type are of two sizes, one very much 

 smaller and the other nearly as large as that of the median 

 nerve. The well developed leptome and hadrome in the median 

 nerve and the larger bundles of the second type are character- 

 istic. The smaller mestome bundles predominate, numbering 

 nine in a leaf. The sterome occurs on upper and lower sur- 

 face of the mestome bundles of the carene, and large sized 

 mestome bundles of second type, but none are found in contact 

 with smaller sized bundles. 



The cells of the chlorophyll bearing parenchyma (c. b. p.) in 

 this species are much smaller than the cells of the other 

 species. 



Tbe uncolored parechyma (p) is found only at the edges of the 

 leaf above the last two mestome bundles. 



PANICUM. 



The large genus Panicum is widely distributed in tropical 

 and warmer countries with a goodly number in temperate cli- 

 mates. The representatives studied by us are common species 

 in the Mississippi valley and southward. The three species, 

 P. capillare L., P. proliferum L., and P. crus-galli L , grow in 

 moist places or where there is considerable rainfall. The 

 weedy P, capillare is perhaps an exception, as it is adapted to 

 a wider range of climatic conditions, the structure of the leaf 



