A STUDY OF CERTAIN FOLIACEOUS COTYLEDONS 261 



to the upper surface of the leaf stalk. Five bundles may be usually 

 recognized in the leaf petiole, the three lower ones being sometimes 

 closely approximated. Here, as in the cotyledon stalk, the endodermis 

 may be recognized extending below the larger bundles. The structure 

 of this cotyledon stalk has been described by Dangeard. 1 



SOLANUM QUITOENSE Lam. 



General. — The cotyledons of this species are distinctly foliaceous; 

 they are ovate in shape with acute apex. The leaves are rather broadly 

 obovate with truncate apex. Scattered glandular hairs are present 

 throughout. A description of the seedling of this plant is given by 

 Lubbock. My plants correspond to his description 2 except that all my 

 measurements are about 50 per cent, greater. 



Epidermis as seen in surface view. — Very little difference is to be 

 recognized between the epidermis of the leaf and that of the cotyledon. 

 Stomata are present on the upper and lower surfaces of both structures 

 but fewest on the upper surface of the leaf. The epidermal cells have 

 a wavy outline, this waviness being more pronounced in the case of the 

 leaf. 



Internal structure. — Both leaf and cotyledon show "shade plant" 

 characters. The palisade is poorly developed and the intercellular 

 spaces large. As my plants were grown in a somewhat shaded situa- 

 tion their structure may be slightly different from the usual. The leaf 

 is much thinner than the cotyledon, the difference being due to the size 

 of the cells. A greater proportion of the total thickness of the leaf is 

 formed by the palisade than is the case in the cotyledon. 



Cotyledon stalk and lea} petiole. — These are of similar form, both 

 being channeled above and rounded below. A single vascular bundle 

 extends through the central part of each. This is somewhat more 

 massive in the leaf petiole. Of all the plants examined this species 

 shows the greatest similarity in leaf petiole and cotyledon stalk. 



Cosmos bipinnatus Cav. 

 General. — In this species the cotyledons are linear while the early 

 leaves are ovate and deeply cleft. The cotyledons increase greatly 



1 Dangeard, Le Botaniste, 1:104, 1899. 3 Lubbock, Seedlings. 2:295. 1892. 



