CHAPTER XVIII 
FRUITS AND SEEDS 
Amon the higher plants, multiplication by seed is almost 
universal. The various modes of vegetative reproduction 
supplement it, but only in a very few cases do they alto- 
gether displace it. For this reason the higher plants are 
called Spermaphytes, or Seed-plants, in contrast to the 
lower plants, or Cryptogams, which multiply by spores, 
and not by seed. 
The Fruit.—Seed-plants are divided into two groups, 
according to whether the seeds are enclosed in fruits or 
not. The Angiosperms, or higher flowering plants, bear 
seeds enclosed in fruits. This fruit is usually developed 
from the ovary. All parts of the flower are looked upon 
as modified leaves, and the leaf-structures which form the 
ovary are known as carpels. If the carpels are separate, 
the ovary is said to be apocarpous (Gr. apo, from, distinct ; 
carpos, fruit); if they are united, syncarpous (Gr. syn, 
together). The number of carpels forming the ovary 
may be one or many, and according to their mode of 
union one or more seed-chambers are formed. The 
ovary is, therefore, a closed structure containing one or 
more chambers, in which one or more seeds are developed. 
When the ovules are fertilized and become seeds, accom- 
panying changes take place in the carpels, and these 
become the enclosing walls of the fruit, and constitute 
the pericarp (Gr. pert, round). In the lower group of 
Seed-plants, the Gymnosperms, the seeds are not enclosed 
in carpels, but are exposed on shoots or seed-bearing 
leaves—e.g., conifers. Nevertheless, even in Gymno- 
sperms seed-protection is not unprovided for. In the 
pine, for example, during the development of the seeds, 
183 
