384 PLANT STUDIES 
COTYLEDON : the first leaf developed by an embryo sporophyte. 
CYCLIC : applied to an arrangement of leaves or floral parts in which 
two or more appear upon the axis at the same level, forming a 
cycle, or whorl, or verticil. 
DEHISCENCE: the opening of an organ to discharge its contents, as in 
sporangia, pollen -sacs, capsules, etc. 
DICHOTOMOUS : applied to a style of branching in which the tip of the 
axis forks. 
DIOECIOUS : applied to plants in which the two sex-organs are upon dif- 
ferent individuals. 
DORSIVENTRAL : applied to a body whose two surfaces are differently 
exposed, as an ordinary thallus or loaf. 
EGG : the female gamete. 
EMBRYO: a plant in the earliest stages of its development from the 
spore. 
EMBRYO-SAC : the megaspore of Spermatophytes, which later contains 
the embryo. 
ENDOSPERM: the nourishing tissue developed within the embryo-sac, 
and thought to represent the female gametophyte. 
ENTOMOPHILOUS : applied to flowers or plants which use insects as agents 
of pollination. 
EPIGYNOUS : applied to a flower whose outer parts appear to arise from 
the top of the ovary. 
FERTILIZATION : the union of sperm and egg. 
FILAMENT: the stalk-like part of a stamen. 
FOOT: in Bryophytes the part of the sporogonium imbedded in the 
gametophore ; in Pteridophytes an organ of the sporophyte embryo 
to absorb from the gametophyte. 
GAMETANGIUM : the organ within which gametes are produced. 
GAMETE : a sexual cell, which by union with another produces a sexual 
spore. 
GAMETOPHYTE: in alternation of generations, the generation which 
bears the sex organs. 
HETEROGAMOUS : applied to plants whose pairing gametes are unlike. 
HETEROSPOROUS : applied to those higher plants whose sporophyte pro- 
duces two forms of asexual spores. 
HOMOSPOROUS : applied to those plants whose sporophyte produces simi- 
lar asexual spores. 
