24 THE STORY OF PLANT LIFE 
When a fruit is simple it is not capable of being 
split up into other fruits. Such a fruit is the acorn 
of the oak or an apple. An aggregate fruit is one in 
which several fruits are collected in one head, but 
are distinct, as in the case of the strawberry. A 
multiple fruit is one in which there are several flowers 
combined to form one fruit. 
Fruits are also of two main types according to 
whether they are dry or fleshy. 
If they open to permit the seeds to fall out they 
are called dehiscent. If they are closed permanently 
the fruit is indehiscent, and these latter are generally 
one-seeded. It is the dry fruits as a rule that 
dehisce. 
Schizocarps are fruits that split up into one-seeded 
members often made up of single carpels. 
Of dry fruits the indehiscent types consist of 
achenes, which are the product of a single carpel, as 
in the Buttercup, Composites, Grasses, and in the 
latter, when the testa and pericarp are united, the 
fruit is called a caryopsis. In the nuts the fruit is 
the product of more than one carpel, and these occur 
amongst Birch and its allies. 
When an achene or nut is winged it is called a 
samara, as inthe Elm or Ash. A form of schizocarp 
is the lomentum, in which the pod (in Leguminosz) 
is constricted, and portions break off at the joints. 
Of dry fruits that are dehiscent there is the follicle, 
which consists of a single carpel which opens along 
the ventral side as in the Sedums. 
