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GLOSSARY 



Introrse, turned inward or toward the 



axis. 

 Involucel, a secondary involucre, as 



that occurring on the umbellet in 



some umbellifers. 

 Involucre, a cycle of bracts subtending 



a flower cluster, head, or single 



flower. 

 Irregular, (of flowers) with the parts 



of a floral set of unequal size and 



shape; zygomorphic. 

 IsocARPic, with the number of carpels 



equal to that of the parts of other 



floral sets. 



Karyolymph, the hyaline fluid or sap 



occurring in a nucleus. 

 Keel, the two anterior, united petals of 



a papilionaceous flower. 

 Key fruit, see Samara. 



Lacuna, an air-space in a tissue. 



Lamella, a thin, flat plate or mem- 

 brane. Cf. Middle lamella. 



Lamina, see Blade. 



Lanceolate, narrow and tapering at 

 both ends, usually broadest above the 

 base and narrowed to the apex. 



Latex, a white or yellow viscous emul- 

 sion. 



Leaflet, one of the divisions of a 

 compound leaf. 



Leaf trace, a bundle which extends 

 to a leaf; or, more inclusively, the 

 complex of all the bundles that supply 

 a single leaf. 



Legume, the dry, dehiscent fruit of 

 leguminous plants developed from a 

 single carpel and usually opening 

 along both sutures. 



Lemma, (in grasses) the lower of two 

 bracts enclosing the flower, some- 

 times called the flowering glume. 



Lenticel, a corky area of loosely ar- 

 ranged cells in the periderm. 



Leucoplast, a colorless plastid. 



Liana, a climbing or twining plant. 



Ligule, a thin, scarious projection 



arising at the top of the leaf-sheath in 



grasses. 

 Limb, the expanded portion of a gamo- 



petalous corolla, or of a petal or leaf. 

 LiNiN, the substance comprising the 



reticulum of the nucleus. 

 LocuLE, one of the chambers in an 



anther or an ovary. 

 LocuLiciDAL, dehiscence of the locule of 



an ovary along the dorsal suture. 



Cf. Septicidal. 

 LoDicuLEs, the small scales outside the 



stamens in the grass flower. 

 Lumen, (of cell) the cavity bounded by 



the cell walls. 

 Lysigenous, applied to a cavity formed 



by the disintegration and dissolution 



of cells, a. Schiiogenous. 



Medulla, the pith. 



Megagamete, the larger of two uniting 



cells or gametes; the egg. 

 Megasporangium, a sporangium in 



which the megaspores are developed. 

 Megaspore, a tetraspore from which 



the megagametophyte develops. 

 Megasporophyll, (in angiosperms) a 



carpel. 

 Mericarp, one of the akene-like carpels 



of the schizocarp of umbellifers. 

 Meristele, a stele in which the vascular 



bundles are distributed throughout 



the axis, i.e., corn. 

 Meristem, a group of embryonic cells 



whose derivatives may differentiate 



into various cell types and tissues. 

 Mesarch, applied to primary xylem in 



which the protoxylem is centrally 



located and the development of the 



metaxylem is both centripetal and 



centrifugal. 

 Mesocarp, the middle layer of the peri- 

 carp. 

 Mesophyll, the parenchymatous tissue 



between the adaxial and abaxial 



epidermis of the blade. 



