Re: Why are Strawberry Seeds on the outside of the fruit?

What most people call seeds on the outside of the strawberry fruit are actually
the true fruits. Technically, they are achenes. In an achene, the single seed is
enclosed by the ovary wall. A sunflower fruit is also an achene.

A strawberry "fruit" is unusual because the red, fleshy part is the enlarged
receptacle. The receptacle is the enlarged tip of the flowering stem to which
the petals, sepals, stamens and carpels are attached. The strawberry is said to
have an accessory fruit because much tissue other than the ovary is part of the
"fruit". Apples and pineapples are also accessory fruits.

The strawberry is also termed an aggregate fruit because it is formed from many
separate carpels of a single flower. Other aggregate fruits are raspberry and
blackberry. 

Some people mistakenly refer to strawberries as a multiple fruit. In a multiple
fruit, the carpels of several flowers merge to form the fruit. Pineapple and
figs are multiple fruits.

Scientific fruit terminology is often confused. Adding to the confusion is that
there are popular definitions for fruit, nut and berry. Most "nuts" are not
botanical nuts. The peanut fruit is a legume. The walnut fruit is a drupe.
Ginkgo nuts are seeds of a gymnosperm, and gymnosperms produce no fruits. Many
berries are not botanical berries. The strawberry fruit is an achene. The
raspberry fruit is a drupe. Juniper berries are seeds of a gymnosperm.  

References


Fruit types and classification of fruits


Seeds and Fruits


Fruit Growth and Fruit Types


Classifying Fruit