434 PLANT MORPHOLOGY 



Cortex. Tho region of a root or stem that lies between the epidermis and the stele. 



Cotyledon. The first leaf, or one of the first pair or whorl of leaves, formed on the 

 embryo of seed plants. 



Cuneate. Wedge-shaped, as an apical cell with four cutting faces. 



Cupule. A small cup-shaped structure, especially in certain liverworts, in which 

 gemmae are produced. 



Cystocarp. A kind of sporocarp, in the red algae, produced after fertilization and con- 

 sisting of the carpogonium, gonimoblasts, carpospores, and often other associated 

 structures. 



Cytoplasm. The protoplasm of a cell exclusive of the nucleus. 



Deciduous. Falling off at the end of the growing season, as some leaves; said of plants 



having leaves of this type. 

 Dehiscence. Bursting open, at maturity, in some regular manner, of a sporangium 



to discharge its spores or of a fruit to liberate its seeds. 

 Dermatogen. A layer of embryonic cells, in a root tip or stem tip, that gives rise to 



the epidermis. 

 Dichotomy. A type of branching in which the main axis forks repeatedly into two 



branches of equal length. 

 Dicotyledonous. Having two cotyledons. 

 Dictyostele. A dissected stele ; a stele consisting of a wide-meshed network of vascular 



strands. 

 Dimorphic. Occurring in two distinct forms upon the same plant or upon other plants 



of the same species. 

 Dioecious. Having the male organs on one plant and the female on another; having 



staminate and pistillate flowers on separate plants. 

 Diploid. Having twice the basic or haploid number of chromosomes. 

 Dolabrate. Hatchet-shaped, as an apical cell with two cutting faces. 

 Dorsal. Pertaining to the back or outer side of an organ; designating the surface 



turned away from the axis, as the underside of a leaf; in liverworts and ferns, 



pertaining to the upper side of the prothallium. 

 Dorsiventral. Having distinct dorsal and ventral surfaces. 



Ectophloic. A siphonostele with phloem external but not internal to the xylem. 



Egg. A female gamete. 



Egg apparatus. In angiosperms, a group of three cells at the micropylar end of the 



embryo sac, consisting of the egg and two synergids. 

 Elater. A filament or filamentous appendage for dispersing spores, as in the capsule 



of a liverwort. 

 Elaterophore. A structure to which a group of elaters is attached. 

 Embryo. A young sporophyte, ordinarily derived from a fertilized egg. 

 Embryo sac. In angiosperms, a large cell within the nucellus of the ovule in which 



the egg is produced and, following fertilization, the embryo develops; the female 



gametophyte of angiosperms. 

 Endarch. Development of primary xylem in a centrifugal direction. 

 Endodermis. The innermost layer of cortical cells in a root or stem. 

 Endogenous. Arising from within; growing from or on the inside. 

 Endophyte. A plant that grows inside another plant of a different species, but not 



parasitically. 

 Endosperm. Nutritive tissue in a young or mature seed, formed within the embryo 



sac and lying outside the embryo. 



