80 SEEDS AND FRUITS 
In developing from a single flower but involving a number of 
pistils, the fruits of the Strawberry and Blackberry are similar 
and are classed as aggregate fruits. 
Pineapple Type. — In the formation of the Pineapple a num- 
ber of flowers are involved, each of which consists of a small 
pistil surrounded by large scales and is borne in the axil of a modi- 
fied leaf. Each ovary with 
its scales and modified leaf 
becomes fleshy to form a 
single fruit. The entire fruit 
of the Pineapple consists of a 
number of these single fruits 
closely packed together on 
an axis which forms the core 
of the Pineapple. Since a 
number of flowers are in- 
volved, fruits of this type 
are known as multiple fruits. 
(Fig. 81.) 
Nut Type.—In the nut 
type of fruit, the ovary is 
hard and is generally partly 
or entirely covered by a 
husk formed by the perianth 
or by bracts which grow up 
from the receptacle. (Fig. 
8&2.) Notice the develop- 
ment of the Acorn shown in 
Figure 838. 
Some Other Familiar Types of Fruits. — In many small fruits 
the ovaries become dry and often hard as the fruit matures. 
They are the kind which when small and one-seeded are often 
called seeds. It has been mentioned that the akenes of the Buck- 
wheat and the cariopsis of the Grasses are fruits with hard ovary 
walls. In the Clovers, Alfalfa, and Beans the ovary wall becomes 
dry and hard when mature, forming the structure known as the 
pod or legume. (Fig. 84.) Many of the so-called weed seeds are 
dry ovaries. In many cases, however, other structures are joined 
with the hardened ovary in the formation of the fruit. In the 
Dandelion and many other plants of the Composite type, the 
Fic. 81.— Pineapple. After Koch. 
