194 PLANT GROWTH 



The embryo is a many-celled early stage of an organism receiving food 

 and protection from the parent. In the case of the plant it is the 

 reproductive stage in the seed. 



Endosperm is the stored food which develops independently of the 

 embryo in an albuminous seed. 



Enzymes hasten the chemical reactions of organisms without entering 

 into their compounds (such as in the digestion of foods). 



An etiolated plant is one with characteristics resulting from deficient 

 light, i.e., less chlorophyll, larger cells, longer internodes and, in 

 complete darkness, very small leaves. 



Exalbum.inous seeds are those in which the endosperm is not developed, 

 but the stored food is in enlarged cotyledons. 



Fertilization is (may refer to) (a) the application of plant food to the 

 soil, or (b) to the union of the male sex cell with the egg cell or with 

 the endosperm nuclei of the ovule. 



Fungi form the group of simple non-green plants known as bacteria, 

 molds, and toadstools. 



A gene is the smallest unit of a chromosome which can determine a 

 characteristic of an organism. 



Heredity is the tendency of the offspring to be like the parents. It is 

 based on the chromosome as the basis for the transmission of such 

 tendency. 



The hilum is the scar caused by the breaking of the seed from its attach- 

 ment in the ovary. 



Hormones are secretions of certain parts of an organism which are 

 carried to other parts of the organism where they promote some 

 special activity. 



Humus is any decaying organism found in the soil. It usually gives the 

 soil a darker color. 



A hybrid is the offspring of two parents whose characteristics differ in 

 one or more ways. 



Hybridizing is the act of developing new plants by bringing in contact 

 the sex cells of two unlike plants, i.e., cross-pollination. 



The hypocotyl is that part of the seedling between the cotyledons, or 

 seed leaves, and the root. 



An internode is that portion of a stem between two nodes, or joints from 

 which leaves and buds appear. 



A m,em,brane is a thin often invisible layer of cells or molecules sepa- 

 rating two kinds or conditions of matter. (A surface-tension mem- 

 brane separates the water molecules in a drop of water from the 

 air.) 



