Micropropagation of Fennel (Foeniculum vulgare Miller)

Abstract

Fennel (Foeniculum vulgare Miller) has been used since the remotest antiquity for its aromatic (anise fragrance), medicinal, and nutritive properties (Hegi 1966; Badoc 1988). Originating in the Mediterranean basin, this plant is now more or less extensively cultivated in all the countries where climate is compatible with its growth, notably in Europe and Asia. As a species, Foeniculum vulgare actually comprises numerous types of fennel that differ in the aspect and height of their vegetative system, shape and size of their fruit, duration of their life span, and composition of their essential oil. These varied types have usually been classified into two subspecies: ssp. piperitum (Ucria) Coutinho and ssp. capillaceum (Gilib) Holmboe (Hegi 1966). The ssp. piperitum consists of uncultivated perennial plants with short, rigid lobed leaves and narrow umbels that produce small fruit devoid of anise fragrance. In contrast, ssp. capillaceum is characterized by linear long, supple lobed leaves, wider umbels, and more or less anise-tasting fruit. The various types now under cultivation belong to the latter subspecies and are grouped into three varieties. The variety azoricum (Miller) Thellung (bulb fennel, Italian fennel, Florence fennel) is an annual in which the hypertrophied sheaves of the basal leaves constitute a “bulb” similar to that of celery; it is also used as a vegetable (mainly in the north mediterranean countries). The variety dulce (Miller) Thellung (sweet fennel, French fennel) comprises generally undersized annuals or biannuals producing sweet anise-tasting fruit mainly used as a condiment (biscuits, bread, etc.). Their essential oil is also used for its therapeutical properties (aromatic stimulant, eupeptic, carminative). The variety vulgare (Miller) Thellung (bitter fennel) is composed of heterogeneous, often elevated perennials whose fruit leaves a bitter after-taste. Richer in essential oil than the variety dulce,this variety is cultivated, particularly in Europe, for the production of trans-anethole, an aromatic component utilized as a flavoring (anise fragrance) in the food industry (drinks, sweets, cakes, etc.). Many wild types are also included in this variety despite the fact that their umbels and their fruits are generally much smaller than those of the cultivated ones.