348 INTRODUCTION TO BOTANY 



Cutinization. The transformation of the outer layer of the epidermis 

 into cutin, a substance which is nearly waterproof and not easily pene- 

 trated by gases. 



Cyclic. An arrangement of leaves or floral organs in such a way 

 that two or more appear upon the axis at the same level, thus forming 

 a cycle or whorl. 



Cytoplasm. The jelly-like living material of the cell. 



Deciduous. Applied to plants which lose their leaves at regular 

 intervals. 



Dehiscence (gaping). The opening of an organ to discharge its con- 

 tents, as in case of anthers, sporangia, and capsules. 



Dermatogen (skin-producer). The layer of young epidermis in grow- 

 ing points. 



Dichogamous. With stamens and pistils not maturing together, as in 

 many plantains. 



Dichotomous (cutting in two). Forked regularly in pairs. 



Dicotyledonous (cotyledons double). Having two cotyledons or seed 

 leaves. 



Dimorphism (two structures). Having two different forms. Long- 

 styled and short-styled flowers of the same species are dimorphous. 



Dioecious (two households). Having the two kinds of reproductive 

 organs borne by separate individuals. 



Dorsiventral. Having the two surfaces differentiated so that one is 

 upper and one lower. 



Drupe. A stone fruit with a fleshy outer and a hard inner layer of 

 the pericarp, as in the walnut, peach, plum, etc. 



Ecology. The study of the relations between the plant and its envi- 

 ronment, including the other living beings with which it has to do. 



Egg or oosphere. The female gamete. 



Egg apparatus. A group of three cells, consisting of the egg and two 

 synergids, one at each side. Found in angiosperms. 



Embryo. The young plantlet within the seed. 



Embryo sac. The cavity within which the embryo develops. 



Endodermis (within the skin). The layer of cells inclosing the fibro- 

 vascular bundle ; the bundle sheath. 



Endogenous (produced within). Originating from internal tissues. 



Endosperm (within the seed). A tissue containing reserve materials 

 developed within the embryo sac. 



Endosperm nucleus. The nucleus of the angiosperm embryo sac from 

 which the endosperm of the embryo sac develops. 



Enzyme. One of the plant secretions which digest substances ex- 

 ternal to the plant, as in carnivorous plants, or reserve materials, as 

 in seeds. 



