Fragaria ( ) is a
genus of
flowering
plants in the
rose family,
Rosaceae, commonly known as
strawberries for their edible
fruits. Originally straw was used as a
mulch in cultivating the plants, which may have led to
its name. There are more than 20 described
species and many
hybrids and
cultivars. The most common strawberries grown
commercially are cultivars of the
Garden strawberry (
Fragaria
×ananassa). Strawberries have a taste that varies by cultivar,
and ranges from quite sweet to rather tart. Strawberries are an
important commercial fruit crop, widely grown in all temperate
regions of the world.
Morphology
The strawberry is an
accessory
fruit; that is, the fleshy part is derived not from the ovaries
which are the "seeds" (actually
achenes) but
from the peg at the bottom of the
hypanthium that held the ovaries. So from a
technical standpoint, the seeds are the actual fruits of the plant,
and the flesh of the strawberry is modified receptacle tissue. It
is whitish-green as it develops and in most species turns red when
ripe. All strawberries have seeds that are visible from the
outside.
A longitudinal section of the fruit reveals (from top to bottom): a
green cap (
Calyx ), light yellow
seeds (
achene), a vascular bundle, a pith,
and a receptacle (
cortex).
History
The woodland strawberry,
F.
vesca, was the first to be cultivated, in the 17th
century.Before that time period it had already been used for
centuries extensively by ancient Persians who knew the fruit as
Toot Farangi.
The typical
cultivated strawberry
comes from the
Americas, and is a
hybrid of the
North American F. virginiana and the
South American F. chiloensis, developed in the
early 18th century.
Classification
There are more than 20 different
Fragaria species
worldwide. Key to the classification of strawberry species is
recognizing that they vary in the number of
chromosomes. There are seven basic
types
of chromosomes that they all have in common. However, they exhibit
different
polyploidy. Some species are
diploid, having two sets of the seven chromosomes (14 chromosomes
total). Others are tetraploid (four sets, 28 chromosomes total),
hexaploid (six sets, 42 chromosomes total), octoploid (eight sets,
56 chromosomes total), or decaploid (ten sets, 70 chromosomes
total).
As a rough rule (with exceptions), strawberry species with more
chromosomes tend to be more robust and produce larger plants with
larger berries (Darrow).
- Diploid species
Fragaria sp.
- Tetraploid species
- Hexaploid species
- Octoploid species and hybrids
- Decaploid species and hybrids
Numerous other species have been proposed. Some are now recognized
as subspecies of one of the above species (see GRIN taxonomy
database).
The
Mock Strawberry and
Barren Strawberry, which both bear
resemblance to
Fragaria, are closely related species in
the genus
Potentilla. The
Strawberry Tree (
Arbutus
unedo) is an unrelated species.
Ecology
A number of species of
Lepidoptera
(
butterfly and
moth)
feed on strawberry plants; for details see
this
list.
See also
Footnotes
- Sunset Western Garden Book, 1995:606–607
- Wiktionary entry for "strawberry"
- http://www.aces.edu/pubs/docs/A/ANR-0633/
References
- Darrow, George M. The Strawberry: History, Breeding and
Physiology. New York. Holt, Rinehart and Winston, 1966.
External links
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