Vitis

Vitis (grapevines) is a genus of 79 accepted species[5] of vining plants in the flowering plant family Vitaceae. The genus is made up of species predominantly from the Northern hemisphere. It is economically important as the source of grapes, both for direct consumption of the fruit and for fermentation to produce wine. The study and cultivation of grapevines is called viticulture.

Most Vitis varieties are wind-pollinated with hermaphroditic flowers containing both male and female reproductive structures. These flowers are grouped in bunches called inflorescences. In many species, such as Vitis vinifera, each successfully pollinated flower becomes a grape berry with the inflorescence turning into a cluster of grapes. While the flowers of the grapevines are usually very small, the berries are often large and brightly colored with sweet flavors that attract birds and other animals to disperse the seeds contained within the berries.[6]

Grapevines usually only produce fruit on shoots that came from buds that were developed during the previous growing season. In viticulture, this is one of the principles behind pruning the previous year’s growth (or “One year old wood”) that includes shoots that have turned hard and woody during the winter (after harvest in commercial viticulture). These vines will be pruned either into a cane which will support 8 to 15 buds or to a smaller spur which holds 2 to 3 buds.[6]

Flower buds are formed late in the growing season and overwinter for blooming in spring of the next year. They produce leaf-opposed cymes. Vitis is distinguished from other genera of Vitaceae by having petals which remain joined at the tip and detach from the base to fall together as a calyptra or ‘cap’. The flowers are mostly bisexual,[7]:143 pentamerous, with a hypogynous disk. The calyx is greatly reduced or nonexistent in most species and the petals are joined together at the tip into one unit but separated at the base. The fruit is a berry, ovoid in shape and juicy, with a two-celled ovary each containing two ovules, thus normally producing four seeds per flower (or fewer by way of aborted embryos).[8]

Other parts of the vine include the tendrils which are leaf-opposed, branched in Vitis vinifera, and are used to support the climbing plant by twining onto surrounding structures such as branches or the trellising of a vine-training system.

In the wild, all species of Vitis are normally dioecious, but under domestication, variants with perfect flowers appear to have been selected.

The genus Vitis is divided into two subgenera Euvitis Planch. have 38 chromosomes (n=19) with berries borne on clusters[9] and Muscadinia Planch. 40 (n=20) with small custers.[10][11]