INDEX. 351 



Knawell (Scleranthus), the genus of ... 108 



Knotgrass, Buckwheat, &ic. (Polygonum), the genus of . 98 



Krigia, how characterized 163 



Labiate flowers of 2 kinds, ringent or gaping, and personate 



or masked 15 



Lady's-slipper (Cypripidium), the genus of . . . 185 

 Larch (Larix), remarks on ...... 198 



Larkspur (Delphinium), the genus of . . . 119 



Lavatera, its generic trait ...... 146 



Laurus, the genus of the Sassafras, Spice-bush, Camphor- 

 tree, &c. 99, 100 



Leatherwood (Dirca), the genus of .... 97 

 Leaves anatomy of, their functions — the respiratory organs 

 of plants — composed of 3 parts ; vis. the vascular, cel- 

 lular, and cuticular layers 282 



their vascular system observable in skeleton pro- 

 ductions 283 



in those of monocofyledonous plants the vessels run 



in gently curved or nearly straight lines, which are 

 either longitudinal or transverse, [v. Plate 11. Fig. 4.] 284 



— a double, or ascending and descending system of 

 vessels, in the sessile leaves of the White Lily, and 

 others of the tribe 285 



— the spiral vessels nearer to the upper than the under 

 disk of leaves ib. 



— the vessels, though nearly parallel, sometimes 

 communicate laterally 286 



the longitudinal foliar vessels, in this tribe of 



plants, a continuation of those near the surface of the 



caudex or stem 286 



Leaves petiolated, 2 divisions of in monocotyledones ; viz. 



with longitudinal or transverse ribs . . . 287 



those of Grasses, examples of the longitudinally 



ribbed kind ib 



of Indian Corn, their vascular structure 287, 288 



the vessels in the foliar expansion, 



unlike those of the petiole ; differ in size . . 289 



examination of the transverse section of the leaf 



of Indian Corn ....... jb, 



transversely ribbed (as in Canna), the peculiarities 



of their vascular structure .... 290,291 

 — A transverse section of the petiole of Canna exam- 

 ined, fv Plate 11. Fig. 3] in which the pneumatic 

 cells in the petiole and midrib are observable, [v. the 

 above Figure] 291 



