The cucumber (Cucumis sativus) is a herbaceous, creeping vegetable plant, of the same family as the African calabash, the melon or the squash (family of Cucurbitaceae). It is botanically a fruit that is eaten like a vegetable. It is of the same species (Cucumis sativus) as the pickle, consumed as a condiment. The plant, which grew naturally at the foot of the Himalayas, was first domesticated in India at least 3,000 years ago.
Description
The large alternate, stipulated leaves, pentagonal with webbed venation, have three to five lobes. The edge of the blade is toothed. The cucumber shows great leaf variability on the same individual.
The unisexual flowers are actinomorphic and pentamerous. Male (with a non-functional pistil) and female (with a gynaecium composed of a tricarpalous ovary) flowers are both pale yellow but distinct, although carried by the same foot (monoecious plant).
The traditional varieties produce flower buds first male, then female, in roughly equivalent proportions. Some hybrid cultivars produce mostly female buds.
The elongated and fleshy fruits, with a rough feel, can reach 30 cm long and 5 cm in diameter. These are berries containing many seeds. Their color at maturity varies according to the varieties from green to white through yellow.
The seeds are yellowish white and very flattened. One gram contains 35 to 40 seeds and their shelf life is long (10 years).
The cucumber is a climbing plant. The stem pushes upward looking for supports to which to anchor. Once found, the stem contracts and forms helical structures called tendrils. The cucumber tendrils are remarkable in that they have two helicoids of opposite directions. The section between the two helicoid is called a "spin perversion" .
VarietiesAmong the different types of cucumbers, three main types are more used:
the short cucumber, with mat skin and often rough surface, called prickly or American cucumber. Some varieties are bitter due to the presence of cucurbitacin.
the long cucumber with shiny bark with a small shrinkage at the end, called the Dutch cucumber or English cucumber, especially in North America. It is not bitter and seedless (parthenocarpy).
the "beit-alpha", also called mini-cucumber or Lebanese cucumber, it is at the same time short, smooth and shiny, less frequent but it begins to supplant the prickly cucumber. It is not bitter, it has no seeds and its size is more suitable for consumption. It is better suited to the climate of the South.
More than 870 varieties are listed in the European Catalog and 45 in the French Catalog. Most are hybrid varieties.
Some varieties:
short-spiny: (non-hybrid) The generous, Marketer ... (hybrid) Sideral ...
Dutch: Acylia, Loustik, Long market garden green ...
beit-alpha: Gynial, Pharo ...
Certain varieties of cucumber are parthenocarpic, the flower buds then producing seedless fruit. Today, professionals only cultivate parthenocarpic varieties. Indeed, cucumbers from non-parthenocarpic varieties are filled with seeds and have a bitter taste.
There is a species called wild cucumber in the Kalahari Desert (see also Kgalagadi Transboundary Park), which together with the metulifer cucumber (Kiwano) and tsamma melons are the only sources of water in the region during the annual drought period. .
Variety improvements
Significant progress has been made in particular in resistance to diseases such as Cladosporium cucumerinum, powdery mildew (Podosphaera xanthii), downy mildew (Pseudoperonospora cubensis), septoria leaf spot (Corynespora melonis), as well as to the yellowing virus of the ribs of the cucumber (CVYV), zucchini yellow mosaic virus (ZYMV).
The innovative CRISPR-Cas9 technique made it possible, by mutation of a single gene, to make a variety of cucumber resistant to at least three potyviruses, ZYMV, PRSV-W and CVYV.