258 UNIVERSITY OF COLORADO STUDIES 



Internal structure. — Vertical sections show some difference in the 

 palisade. This consists of a single row of rather short cells in the coty- 

 ledon, while in the leaf there is one row of long cells next the epidermis 

 and another row of short cells below the first. The cells composing the 

 upper epidermis of both leaf and cotyledon are of relatively enormous 

 size, being nearly as deep as the palisade cells. In the leaf the epidermis 

 becomes two-layered. A similar epidermis has been recorded 1 for 

 certain other Bombacaceae, but apparently this particular plant has not 

 been previously examined. 



Cotyledon stalk and leaf petiole. — A marked difference is seen in these 

 structures. The former is flattened, channeled above and rounded 

 below, while the latter is nearly cylindrical. There is a single broad, 

 flat, bow-shaped vascular bundle in the cotyledon stalk and about eight 

 bundles, arranged in a circle, in the leaf petiole. Eventually these eight 

 bundles cannot be distinguished in the complete vascular cylinder 

 produced. 



BOMBAX MALABARICUM D.C. 



General. — This plant is known as the "red cotton tree," the name 

 serving to distinguish it from the species just described. The cotyledons 

 are distinctly leaf-like in appearance and texture resembling strongly 

 those of Eriodendron anfractuosum. There are, however, certain constant 

 differences in the venation. The first foliage leaf of Bombax is pal- 

 mately three-parted. The later leaves are five-parted. 



Epidermis as seen in surface view. — None of the cells have a very 

 wavy outline. Stomata occur an the under surface of the leaves and 

 cotyledons but not on the upper surface of either. In this species, as 

 other species which I have examined, the stomata are more abundant 

 on a given area of the leaf than on a like area of the cotyledon. Numer- 

 ous bulbous, multicellular trichomes are placed on the lower surface 

 of the leaf and a few of these occur on the cotyledon. There are fine 

 ridges on the surfaces of the epidermal cells of the leaf but these were 

 not observed on the cotyledon. 



Internal structure. — The upper epidermis of the leaf becomes two- 

 layered as the leaf reaches its full size. Whether a like tangential divi- 



1 Solereder. Syst. Anat. der Dicotyledonen. 167. 189Q. 



