786 GLOSSARY. 



Involute. Applied to leaves in vernation, and to petals in estivation, i.e., 

 when both margins are inrolled lengthwise on the ventral surface 

 (p. 364). 



Irregular. Flowers in which the parts of the same circle show some 

 irregularity in size or form, as in the Labiatae (p. 393). 



Isodiametric. Having the same diameter in all directions. 



Isosporous. A plant which produces but one kind of sporangium and 

 one kind of asexual spores (p. 87). 



Keel (Carina). See Carinal. 



La'ciniate. Cut into narrow pointed lobes. Applied to leaves and leaf- 

 like organs. 



Lamellae. Layers ; applied to the concentric markings or layers in starch 

 grains (p. 144) and cell walls (p. 259). 



Lanate. Hairs that are matted. 



Lanceolate. Lance-shaped. Applied to narrow leaves which gradually 

 taper toward the summit, as in Senna. 



Laticiferous. Cells or vessels containing latex (p. 239). 



Legume. An elongated, monocarpellary, usually dry fruit, in which de- 

 hiscence takes place along both sutures (p. 419). 



Lenticels. Biconvex rifts on the outer surface of the trunk and older 

 branches of trees, as the bark of cherry and birch. 



Lenticular. In the form of a double convex lens. 



Leptome (Sieve). The conducting cells in the phloem (p. 276). Also 

 employed to include the accompanying cells and cambiform (p. 341). 



Libriform. Wood fibers; the strengthening cells of the xylem (p. 270). 



Ligulate. Applied to a narrow, flattened, gamopetalous corolla, as in the 

 ray flowers of the Compositae (p. 311). 



Ligule. The membranous projection at the summit of the sheath of 

 grasses and sedges. 



Lobed. A leaf margin in which the incisions extend about half way into 

 the lamina, and the sinuses and the lobes are more or less rounded, as 

 in the white oak (pp. 356 and 511). 



Lyrate. A pinnately-cleft leaf in which the lobes increase in size toward 

 the summit, the latter being large and rounded, as in the lyre-leaved 

 sage. 



Lysigenous. Applied to receptacles or reservoirs, formed by the disin- 

 tegration of a number of cells. They usually contain mucilage, vola- 

 tile oils or resins (p. 26). 



Macrosporangium ( Megasporangium). The sporangium in the higher 

 heterosporous plants which produces only megaspores (p. 101). 



Macrospore (Megaspore). The spore which produces the female game- 

 tophyte (p. 101). 



Macrosporophyll (Megasporophyll). A sporophyll which produces only 

 megasporangia (p. 101). 



Marcescent. Withering, but more or less persistent, as the style and 

 stigma. 



Membranous (Membranaceous). A thin, pliable and more or less trans- 

 lucent structure. 



Mericarp. One of the two inferior achenes of the fruit of the Umbelli- 

 ferae (p. 417). 



Meristem. Cells that possess the property of dividing and forming new 

 tissues (pp. 253. 254 and 291). 



Mesocarp (Sarcocarp). The middle layer of the fruit wall (p. 410). 



Mestome Strand. A fibrovascular bundle without either wood or bast 

 fibers (p. 341). 



Metabolism. All of the chemical changes involved in the activity or 

 growth of the organism (p. 252). 



