A strawberry

“I sure do like strawberries”, said one friend to another. The other, who had just finished a college course in Botany said “You know, strawberries are not really berries.” “What do you mean, they are not berries?” replied the first. “Well, a berry is the product of a single flower which develops a fleshy exterior from the ovary wall… you know, like a tomato or a cucumber.” “You mean a tomato is a berry, but a strawberry is not? What about a cherry, what is it?” “Drupe” replied the veteran of the Botany course. “Don’t you call me a dupe!” interjected the first. “No, no a drupe, not a dupe! a dupe, I mean a drupe, is a fruit with a stony pit…” and so it went…

Closeup photograph of a strawberry

Actually, strawberry fruits are a bit complicated. What we call the flower is a composite of many small flowers. Each of these flowers eventually forms one of the small yellow structures that we see scattered over the surface of the fruit. Each of these structures is actually an ovary with a seed inside.  They are similar in structure to a sunflower seed. The fleshy part of the strawberry, derives from tissue at the base of the flower on which the ovaries were mounted, not from the ovary wall.

The closeup above shows the “seeds” on the surface of the strawberry. The filaments that can be seen protruding from some of the seeds are the remains of the stigma, the female structure which receives the pollen during fertilization.

A strawberry on which one of the seeds has germinated

I found this strawberry in a box from the grocery. One of the seeds on the surface of the fruit has germinated to form a small plant.

Detail of a small plant growing on the surface of a strawberry

A closer look at the small plant shows that it is apparently trying to develop a flower. Many yellow structures which are apparently stamens can be seen in the center. The large whitish structure is apparently trying to become a petal.

The strawberries we grow commercially (Fragaria × ananassa) are hybrids between a North American species (Frageria virginiana) and a species from South America (Frageria chiloensis). The hybrids we grow now were first developed in France in the 18th century, but a large number of varieties have been produced by plant breeders over the years.