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This text from:

The Species of Fragaria, their Taxonomy and Geographical Distribution by G. Staudt.

Originally printed in:

Acta Horticulturae 265, 1989 - Strawberry Symposium

Introduction

The basis for investigations into the genetics of strawberries, and also for breeding work, is a knowledge of the genetic diversity within the genus. Because, very often the differential characteristics cannot easily be identified in herbarium specimens, many investigators, including Linneus (1753), have put forward incorrect classifications for the species and subspecific entities. For this reason, many species described in the monographs of Rydberg (1898,1908) and Losina-Losinkaja (1926) cannot be recognized and are now considered to be synonyms or subspecific taxa. As has already been pointed out by Duchesne (1766), an improved taxonomy can be achieved by the use of living material collected at original localities. Therefore, an extensive collection of over 500 accessions of wild growing strawberries from all over the world was investigated, as well as specimens from the main herbaria including those which possess many of the type specimens described by the monographers mentioned above.


Diploids (2n=2x=14)

Fragaria vesca (woodland strawberry)

F. vesca flower F. vesca berry

It can be divided into four subspecies (ssp):

  1. The European ssp vesca has relatively small flowers and erect inflorescences which mostly exceed the leaves, even when berries are ripe. The berries are subglobose to somewhat ovoid and the calyx is always reflexed. The berries separate from the calyx and have a highly aromatic flavor.
  2. The berries of ssp. americana are more or less elongated, somewhat pointed, and the calyx is always reflexed.
  3. The berries of ssp. californica are subglobose to elongated and the calyx is reflexed. The achenes of all three subspecies are superficial or in shallow pits.
  4. The third American ssp. bracteata differ from the others in several characteristics: the flowers are significantly larger, the calyx is spreading to appressed to the berries, and the achenes are set in deep pits. Whereas the other subspecies are always self fertile hermaphrodites, ssp. bracteata shows a special breeding system with both hermaphrodites and occasional females. Therefore, it must be called gynodioecious.

F. viridis

A second diploid species that occurs in Europe. It is distinguished from F. vesca by its relatively large flowers and fewer flowered inflorescences. It is hemaphroditic but always self-incompatable. The berries are often only partially red colored, quite large, and the scapes lie along the ground when the berries are ripe. The calyx is usually appressed to the berries, and the achenes are set in deep pits.

F. nubicola

F. nubicola is one of the four diploid species which can be recognized from central Asia. It shares several characteristics from F. viridis but differs in the runner type which are sympodial in nubicola.

F. daltoniana

The plants of this species are rather slender. The berries are ovoid to cylindrical with spongy, tasteless flesh. A typical characteristic of F. daltoniana, which can be found in the octoploid F. chiloensis, are its shiny, coriaceous leaves.

F. nilgerrensis

This species always forms rather robust plants with roundish leaflets. The berries are subglobose, white with many small achenes. They taste somewhat banana-like.
The ssp. hayatai from Taiwan is distinguished by its having anthcyanins in all parts of the plant, even the berries.

F. nipponica

The leaflets of this species are elliptical-oval, serrate to serrulate. The flowers are medium-sized and self-incompatable. The berries are subglobose to cylindrical with a rather unpleasant taste.

F. yezoensis

A second diploid species from Japan, this species grows vigorously.

F. iinumae

Examples of fruit

 








This species represents an entirely different type within the diploid species because of its glaucous leaves, which somewhat resemble those of the octoploid F. virginiana ssp. glauca. The flowers always have more than five (six to eight) petals. The berries are elongated with a small calyx and the flesh is spongy and nearly tasteless.


F. mandshurica

This species differs from F. vesca in a number of characteristics but corresponds in some with the tetraploid F. orientalis, which is distributed partly in the same range as F. mandshurica (Staudt 2003). This species may therefore be considered to represent the diploid ancestor of F. orientalis. F. mandschurica is a hemaphroditic partly self-incompatible species. The berries are subglobose to obovoid with mostly yellow collored achenes sitting in shallow pits. The berries always show high acidity.


Tetraploids (2n=4x=28)

F. orientalis

The leaves and teeth of the tetraploid F. orientalis are courser and the flowers are larger than those of F. mandschurica and they show a sexual dimorphism in size. The species is trieocious, meaning that, besides female and male plants, hermaphrodites occur. The hermaphrodites are, according to the monofactorial tetrasomic inheritance of sex, of the quadruple nulliplex type. The berries are quite large, obovoid and taste that of F. mandschurica.

F. corymbosa

A second tetraploid species is known only as a male plant. Its leaflets are somewhat oval. From crossing experiments, it can be deduced that the achenes must sit in deep pits.

F. moupinensis

This species is characterized by its serrate elongated-oval leaflets and its large dioecious flowers. The inflorescences have few flowers, the berries are orange-red colored, the achenes are set in deep pits, and the flesh is spongy and nearly tasteless.


Hexaploid (2n=6x=42)

F. moschata

This is the only hexaploid species known. It is a rather vigorous species. The leaflets are somewhat rhomboid, the inflorescences mostly exceeding the leaves, and the flowers are large and dioeicious or trioecious. Due to the weight of the ripe berries, the scapes lie along the ground. The calyx is usually reflexed. The berries have a strong musk-like taste and smell giving rise to their name, F. moschata.


Octoploids (2n=8x=56)

F. iturupensis

This species was recently described on the island of Iturup of the coast of northern Japan. As an octoploid species, it shows some resemblance to F.virginiana with respect to the leaves, their texture and color. It is, however, hemaphroditic and fully fertile. The berries, although larger, otherwise resemble those of F.vesca - having recessed calyxes and extremely superficial achenes.

F. chiloensis (beach strawberry)

History:

In 1712, Frezier brought five plants of a large-fruited strawberry from Chile to Europe. It was in cultivation at that time in Chile, Bolivia, Peru and Ecuador and is still cultivated there today. This species is not known for growing in the wild, but in southern Chile and Argentina, a wild strawberry grows in the area occupied by the cultivated F. chiloensis. The plants of this one correspond to the cultivated ones, but the size of the berries is markedly different. It can be supposed that a mutation or number of mutations resulting in the gigas fruit type may have arisen in the wild and encouraged the indigenous people to cultivate them. It is also possible, however, that the mutations may have occurred when the plants were already in cultivation and artificially selected by the cultivators. Whatever origins, the step to the gigas type of F. chiloensis was one of two important steps in the origin of cultivated strawberries. The second step was due to Frezier bringing only female plants back to Europe. These plants easily hybridized with the other octoploid species F. virginiana to give rise to the large fruited cultivated strawberry F. × ananassa.

The South American F. chiloensis is treated as the typical subspecies together with three other subspecies from North America and Hawaii. The ssp. pacifica is found near the Aleutian Islands southwards to California near San Francisco and the ssp. lucida from the Queen Charlotte Islands to San Lui Obispo Co, California. They are found only along the coast of the Pacific Ocean. The berries are of different sizes, shapes, and colors; they always have a sweet taste. The achenes are quite large and dark brown. The calyx is large and usually clasping the berries. Ssp. sandwicensis is growing endemically on some islands of the Hawaiian archipelago.

F. virginiana

F. virginiana berry

F. virginiana can be divided into four subspecies.

  1. The ssp. virginiana probably survived in the eastern states south of maximum glaciation. After the ice retreated, it spread northward towards New Foundland and to the northwest as far as Yukon Territory.
  2. ssp. glauca Belongs to the western element of the North American flora. Its area of distribution extends along the Rocky Mountains from southern Arizona, and postglacially, it spread northwards up to Alaska.
  3. The ssp. grayana is found frm New York to Alabama, Louisiana, and Texas.
  4. ssp. platypetala occurs from British Colombia to California and in the Rocky Mountains from Wyoming to Colorado. It is characterized by its broader leaflets, larger flowers, and berries similar to those of F. chiloensis. This subspecies is considered the final link of an introgression of F. chiloensis into F. virginiana ssp. glauca. The introgression may have had its starting pount in the region of the Fraser River Valley, the only area where both species could have met. Here, hybridization probably occured after glaciation.

F. × ananassa notomorph cuneifolia

Hybrid populations of F. chiloensis and F. virginiana still exist in the region from Vancouver Island along the coast south to Fort Bragg, California. They were first described by Nuttal as F. cuneifolia. As this taxon is considered to originate from a hybrid it should be called F. × ananassa notomorph cuneifolia. Plants further away from the coastal area, have decreased characteristics of F. chiloensis. Plants with somewhat thinner leaflets but some other characteristics of F. chiloensis are combined into ssp. platypetalaof F. virginiana.

F. × bringhurstii

Another intregression in California has been investigated by Bringhurst (1963). At several localities where the diploid F. vesca ssp. californica occurs near the coast, where hybridization with the octoploid F. chiloensis likely took place. As a result, pentaploid hybrids have been found and also offspring with 2n=42 and 2n=63 chromosomes.