Strawberry (Fragaria X ananassa)

ROSACEAE, Rose Family

The strawberry is a perennial herb of temperate climates, and in both the Old and New World, small-fruited woodland species were eaten in pre-Christian times. Fragaria vesca, which is a diploid (2n), ever-bearing strawberry, was enthusiastically cultivated in Roman gardens.

The main plant has a short stem with a rosette or crown of trifoliate leaves. The "maiden" or mother plant produces new plantlets by runners, technically stolons, which form roots where a node touches the ground. A strawberry plant is often handled as a biennial, so that the maiden is removed after the new crop of plantlets is established, even though the plant can form fruits on the mother plant for a number of years.

Flowers and fruits are produced on a stalk that emerges from an axillary bud. Each flower is subtended by bracts and has five or more green sepals, five separate white petals, numerous stamens, and a domed receptacle (called a torus) that bears an indefinite number of pistils. The pistil (ovary plus style and stigma) develops into a one-seeded, dry fruit, called an achene; the achene is the hard structure found embedded on the fleshy receptacle, which becomes greatly enlarged. Therefore, this edible "fruit" is actually an aggregate fruit, which describes the situation in which two or more separate fruits (here, the numerous achenes) are formed within a single flower (here, borne on a fleshy receptacle of that flower).

The common name of the plant comes from an Anglo-Saxon word, and various authors have speculated on the origin of this name. Although some writers thought "straw" referred to the practice of covering the plant with straw to protect it from freezing, it seems that this was not the original source. In Old English, the expression "to straw" means "to scatter, spread, or disperse." Consequently, the common name seems to refer to the runners of the plant, which cause the plant to "stray." The name of the genus is derived from the Latin word fragum, which means fragrant.

The strawberry-growing industry started on a large scale around Paris in the 1600s, when the European strawberry was used. In 1714, Amédée Frézier, an engineer and mathematician hired for mapmaking by Louis XIV, returned from an assignment in Chile with five plants of the Chilean strawberry, F. chiloensis. The fruits of this species form early in the spring and are large; however, gardeners experienced problems in growing this species in parts of Europe, because these plants would not bear fruits. In the 1750s, the Chilean species received full attention when growers realized that the plants were often pistillate (female only), and they needed pollen to set fruits. Therefore, in Brittany they began the practice of including one plant of F. vesca as a pollen source for every six plants of the Chilean species.

The first record of the "pine strawberry" was by Philip Miller of Chelsea, England (1759), a very famous horticulturist. The pine strawberry began the modern era of commercial strawberry culture. This form is an octoploid (8n) and apparently arose as a hybrid between F. chiloensis and F. virginiana, a strawberry from eastern North America. The octoploid is often called F. ananassa ("ananas" refers to pineapple). Perhaps the most important early selection was made by Michael Keens (1806), who "invented" the cultivar Keen's Imperial by choosing one plant from a batch of hybrids. For this lucky selection, Keens received the distinguished Silver Cup from the Royal Horticultural Society of London.

Much selection and breeding has been done since Keens to produce plants that bear for long seasons and produce many large, sweet aggregate fruits. California has the highest production of strawberries per hectare of anywhere in the world--over 100 tons per year! Especially near-coastal zones of Ventura County form the heartland of production. This crop requires skilled hand picking and field packing for the fresh market.

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