PLANT ORGANS AND ORGANISMS 
155 
if two carpels enter into its formation, it is said to be dicarpellary; 
if three, tricar pellary; if many, poly car pellary. 
Compound Pistils are composed of carpels which have united to 
form them, and therefore their ovaries will usually have just as 
many cells (locules) as carpels. When each simple ovary has its 
placenta, or seed-bearing tissue, at the inner angle the resulting 
compound ovary has as many axile or central placentae as there are 
carpels, but all more or less consolidated into one. The partitions 
are called dissepiments and form part of the walls of the ovary. If, 
however, the carpels are joined by their edges, like the petals of a 
gamopetalous corolla, there will be but one cell, and the placenta 
will be parietal, or on the wall of the compound ovary. 
The ovules or megasori are transformed buds, destined to become 
seeds in the mature fruit. Their number varies from one to hun- 
dreds. In position, they are erect, growing upward from the base 
of the ovary, as in the Compositse; ascending, turning upward from 
the side of the ovary or cell; pendulous, like the last except that 
they turn downward; horizontal, when directed straight outward; 
suspended, hanging perpendicularly from the top of the ovary. 
In Gymnosperms the ovules are naked; in Angiosperms they are 
enclosed in a seed vessel. 
A complete angiospermous seed ovule which has not undergone 
maturation consists of a nucellus or body; two coats, the outer and 
inner integuments ; and a funiculus, or stalk. Within the nucellus 
is found the embryo sac or megaspore containing protoplasm and a 
nucleus. 
The coats do not completely envelop the nucellus, but an opening 
at the apex, called the foramen or micropyle admits the pollen tube. 
The vascular plexus near the point where the coats are attached to 
each other and to the nucellus is called the chalaza. The hilum 
marks the point where the funiculus is joined to the ovule, and if 
attached to the ovule through a part of its length, the adherent 
portion is called the raphe. The shape of the ovule may be ortho- 
tropous, or straight; campylotropous, bent or curved; amphitropous, 
partly inverted; and anatropous, inverted. The last two forms are 
most common. A campylotropous ovule is one whose body is bent 
so that the hilum and micropyle are approximated. 
