Genus: Fragaria (strawberries)

Life > eukaryotes > Archaeoplastida > Chloroplastida > Charophyta > Streptophytina > Plantae (land plants) > Tracheophyta (vascular plants) > Euphyllophyta > Lignophyta (woody plants) > Spermatophyta (seed plants) > Angiospermae (flowering plants) > Eudicotyledons > Core Eudicots > Rosids > Eurosid I > Order: Rosales > Family: Rosaceae

Fragaria ananassa (Modern Garden Strawberry), a hybrid from other species, is the strawberry as we know it today. [photo H.G. Robertson, Iziko ©]

Fragaria x ananassa, Vienna Botanical Gardens, Austria. [photos H.G. Robertson, Iziko ©]

Strawberry fruit are eaten raw or used in making juice, desserts, jam, syrup and wine. Fruit, leaves and roots are also used medicinally. The Modern Garden Strawberry Fragaria ananassa, which is the main species grown these days, arose in the gardens of Europe as a hybrid between two New World species that had been introduced to Europe by the Spanish colonists.

There are 12 or so species of Fragaria and the genus is native to the north temperate regions (Eurasia, North America), and also extends into North Africa and down through tropical American mountains into temperate South America (e.g. Chile). The number of sets of chromosomes varies from species to species ranging from 2 sets in the Wild Strawberry Fragaria vesca to 8 sets in the Modern Garden Strawberry Fragaria ananassa. 

In a strict botanical sense, the strawberry fruit is not a true fruit, but is termed a pseudocarp. Fragaria belongs to the family Rosaceae in which there are a whole lot of individual female reproductive organs, termed carpels, in the flower. Each carpel consists of a stigma, style and ovary and all the carpels are inserted on to a fleshy receptacle. In Fragaria, the receptacle swells into the red-coloured 'fruit' we know as a strawberry and over its surface are black dots, each dot being an individual true fruit (a true fruit being the ripened ovary). The individual true fruit are termed achenes these being small, dry single seeded fruit that do not split open. It is interesting to contrast the strawberry with the Blackberry (or any other species in the genus Rubus) which is also in the Rosaceae and which also has multiple carpels inserted on a receptacle. Instead of the receptacle swelling to form the fruit, the individual ovaries of the carpels become black and fleshy and in combination they form the Blackberry. So strictly speaking, the Blackberry is also not a true fruit but an aggregation of separate fruit, but in a loose botanical sense, it is OK to call strawberries and blackberries fruit.

Strawberries are eaten by birds which disperse the seeds widely. Strawberry plants also spread vegetatively using runners and this enables them to be easily transplanted and propagated as clones. Strawberry species are generally dioecious (male and female flowers on separate plants) but hermaphroditic flowers did occur rarely in the wild and these were selected for in domestication because it simplified crop production and enabled a crop to all be cloned from a single source. 

 The Wild Strawberry or Wood Strawberry Fragaria vesca is native to the temperate regions of Eurasia and North America. It has become distributed worldwide and is sometimes found naturalised in southern Africa. It is a diploid species (i.e. 2 sets of chromosomes).The finding of strawberry achenes in neolithic archaeological excavations, shows that wild strawberries have been eaten by people since the earliest of times. Fragaria vesca was being cultivated in Europeans gardens by the 1500's (Renaissance) and after about 1530, cultivated strawberries are clearly larger than wild ones, indicating selective breeding. Although Fragaria vesca is still grown in gardens for domestic use, it is not used in commercial strawberry production because of the development of the Modern Garden Strawberry Fragaria ananassa.

The Hautbois or Musk Strawberry Fragaria moschata is native to highland areas from France through to Siberia. It is a hexaploid species (i.e. 6 sets of chromosomes). Like Fragaria vesca, it started being cultivated in European gardens from the 1500's and was still being cultivated widely in the 1600's. However, with the arrival of Fragaria virginiana and Fragaria chiloensis from the New World, growing of this species became severely curtailed in favour of these new, more favourable species and especially the new Modern Garden Strawberry that arose through hybridization of these two species. 

The Virginia Strawberry Fragaria virginiana is native to North America and its flavour, size and abundance made it a popular fruit amongst Indian tribes and also amongst European colonists. During the 1620's, it started being cultivated in Europe. It is an octoploid (8 sets of chromosomes).

The Chilean Strawberry Fragaria chiloensis is also an octoploid and native from Alaska to California. It also evidently became dispersed in prehistoric times by birds to Hawaii, Chile and Argentina. It had been domesticated by the Araucanians in Chile before the Spaniards arrived. They selected for large-fruited varieties. The colonists spread it widely within Central and South America but it was evidently only introduced to Europe in the early 1700's.

The Modern Garden Strawberry Fragaria ananassa is also an octoploid. It is a hybrid between the domesticated Fragaria virginiana with its hermaphrodite flowers and tasty fruit, and Fragaria chiloensis with its large fruit. The hybrid arose within Europe and might have done so a number of times, whenever the two parent species were interplanted. It is of such superior size and quality that it has become the main species in commercial strawberry production. Strawberry varieties have been selected to favour particular climates and to be day-length neutral so that they flower and fruit under both short and long day lengths, thus enabling them to be harvested over a long season in frost-free regions.

Uses

Strawberry fruit are eaten raw or used in making juice, desserts, jam, syrup and wine. Leaves are used in blended herbal teas.  Leaves and roots are believed to have medicinal benefits in terms of easing diarrhoea, digestive upsets and gout. The fruit juice is evidently used externally to counteract sunburn, skin blemishes and discoloured teeth.

References

• Brown, D. 2002. The Royal Horticultural Society New Encyclopedia of Herbs and their Uses. Dorling Kindersley, London.

• Sauer, J.D. 1993. Historical geography of crop plants - a select roster. CRC Press, Boca Raton, Florida.

Text by Hamish Robertson