l8 9i] . Anatomical Characters of Uniola. 171 



The mesophyll in this species forms in a transverse section 

 an interrupted line, being in immediate contact with the epi- 

 dermis of the inferior face, except where it is interrupted by 

 the large mestome-bundle of first or second degree. It is on 

 the contrary almost entirely separated from the superior epi- 

 dermis by the stereome and the uncolored parenchyma under 

 the bulliform cells. The mesophyll showed a rather firm 

 structure without any lacunes. 



These are the general features of the anatomical structure 

 of the leaf of Uniola latifolia, and it will be shown in a follow- 



th 



the corres- 



ponding ones in the other species are of truly specific rank. 

 U. S. National Museum, Washington^ D. C. 



Explanation of Plate" XV. — Sections of the leaf of Uniola latifolia. 

 Fig. 1. Epidermis of the superior, face, X240. Fig. 2. Transverse section 

 through the middle part of the blade, the carene. The black part of the figure 

 represents the mesophyll, which borders on the large uncolored tissue of pa- 

 renchyma. The mestome bundles with their parenchyma sheaths and groups 

 of stereome are to be seen in the mesophyll. Six rather large bundles of ster- 

 eome (S) are to be seen on the superior face, the concave part of the carene. X 15. 

 Fig. 3. Transverse section through a part of the blade, next to that figured in 

 fig. 2. Five groups of the large bulliform cells are to be seen at B. X 75. 

 Fig. 4. Thorn-shaped expansion from the superior face, X320. Fig. 5. Hair 

 from the inferior face, X320. Fig. 6. Transverse section of one of the largest 

 mestome bundles of the carene, showing the partly green parenchyma sheath, 

 the leptome above and the hadrome below. The ieptome is surrounded by t 

 sheath of very thick-walled mestome-parenchyma bordering on a group of 

 stereome. X50O. Fig. 7. Transverse section of a small mestome bundle, that 

 next to the midrib. Three cells of the green parenchyma sheath show a dis- 

 tinct thickening of the cell wall. A group of stereome borders on the leptome 

 side. X560. Fig. 8. Transverse section of a small mestome bundle from one 



of the lateral parts of the blade. There is a horseshoe-shaped sheath of thick- 

 walled parenchyma on the leptome side, and the proper parenchyma sheath 

 shows four uncolored cells, while the other ones contain chlorophyll. X580. 

 Fi g B Transverse section of a small mestome bundle, not far from that 

 figured in fig. 8. The parenchyma sheath is perfectly green, and there is no 

 thick- walled parenchyma inside this. X580. 



