In this article we will discuss about:- 1. Characters of Vitaceae 2. Distribution of Vitaceae 3. Economic Importance 4. Affinities 5. Important Type.
Characters of Vitaceae:
Plants climbing shrubs or small trees, leaves compound or simple deeply lobed; flowers small, hermaphrodite or polygamous – dioecious in spike, racemose, panicles or cymes; sepals 4-5, connate, cup-shaped, petals 4-5, poly or connate at the apex, caducous; stamens 4-5, antipetalous; carpels 2-8, syncarpous, ovary superior; fruit a juicy berry.
A. Vegetative characters:
Habit:
Mostly vines climbing by tendrils, shrubs or small trees.
Root:
Tap and branched.
Stem:
Weak, climbing by tendrils, which are borne at the nodes, opposite to the leaves.
According to Eichler, each tendril represents the tip of the main axis which has been pushed aside by the stronger growth of the branch borne in the axil of the apposed leaf. The branching is cymose scorpioid and the stem is thus a sympodium. Sometimes, the stem may be erect. The nodes are swollen or jointed. Sometimes tendrils develop adhesive discs.
Leaf:
Alternate or opposite, mostly compound, palmate or pinnate, rarely deeply-lobed and simple (Vitis), leaf bases expanded into membranous stipules. Pellucid puncate dots frequently present.
B. Floral characters:
Inflorescence:
Spike, racemes, panicles or biparous cyme.
The peduncle is often tendril like or coiled sometimes partly flower-bearing and partly tendrillar.
Flower:
Small, actinomorphic, hermaphrodite; the plants usually monoecious, dioecious in some species, hypogynous or slightly perigynous.
Calyx:
Sepals 4-5, connate or shortly toothed, entire calayx cupular.
Carolla:
Petals 4-5 connate at the apex only, valvate, caducous, falling off as a cap.
Androecium:
Stameus 4-5, free or connate at the base, inserted opposite the petals and below the disc; intrastaminal disc is prominent, anular expanded or glandular, anther introrse.
Gynoecium:
Bicarpellary syncarpous (sometimes, 3-8 in Leea); ovary-2-celled (Vitis) or 6-celled (Leea), more or less embedded in the circular disc, each loculus with 2 ascending anatropous ovules; style simple; stigma terminal, capitate or discoid.
Fruit:
Succulent berry.
Seed:
Testa hard, ruminate endosperm, embryo small.
Pollination:
Entomophilous.
Floral formula:
Distribution of Vitaceae:
Vitaceae or grape family of 11 genera with 600 species distributed in damp tropical countries; in Africa and south America many succulent xerophytic forms belonging to Cissus is found. C. quadrangularis L. is plentifully found in the plains of Bengal and in other parts of India.
The genus Vitis is temperate and subtropical occurring also in northern parts of the globe. Vitis vinifera L., a Mediterranean genus is cultivated in central and south Europe for wine manufacture. Raisins and currants are dried fruits of Vitis vinifera L.
Economic Importance of Vitaceae:
1. Food:
The fruits of Vitis vinifera i.e. grapes (H. Angur) are used as food. Raisins and currants are the dried fruits of a seedless variety of the grape-vine. Raisins are the dried fruits of certain varieties, comparatively rich in sugar.
2. Medicinal:
Certain species of Vitis and Cissus are medicinal; leaves of Cissus selosa- roasted and oiled are applied to indolent boils to bring them to suppuration. Dried and powdered levels of Cissus quadrangularis are given in bowel infections.
3. Ornamental:
Parthenocissus quinquefolia (Virginia creeper) and several species of Vitis and Cissus are cultivated as desirable house plants.
Affinities of Vitaceae:
The family is closely allied to Rhamnaceae showing a similar floral structure, namely 4 to 5 sepals, petals and stamens, the stamens being antipetalous and generally a bicarpellary pistil; ovary seated on or more or less sunken in a well-marked disc.
It differs, however, in its climbing habit which is rare in Rhamnaceae, by the succulent berried fruits and seeds with copious endosperm and small embryo. The flowers are hypogynous or slightly perigynous but never epigynous.
The suppression of the antisepalous whorl of stamens suggests its derivation from the ancestor of Rutaceae, further this is corroborated by presence of pellucid punctate dots in the leaves in many cases.
Common plants of the family:
1. Cayratia carnosa – a small herb, without tendril but fairly large leaves.
2. Cissus quadrangularis – a climber with quadrangular herbaceous sympodial stem.
3. Leea aspera – A robust spreading shrub.
4. Parthenocissus quinquefolia – Virginia creeper – well known because of its brilliant autumn foliage.
5. Vitis – Latin name of vine. Vitis vinifera – grape-vine H. Angur, cultivated for its delicious juicy fruits.
Important Type of Vitaceae:
Vitis vinifera (Grape-vine) (Fig. 48.1):
Habit:
Tendril-climbing vine.
Root:
Tap-root.
Stem:
Weak, sympodium, climbing by leaf-apposed, simple or branched tendrils which represent modified scorpioid shoots.
Leaf:
Simple, alternate, palmate, multicostate, reticulate.
Inflorescence:
Flowers small, yellowish-green, in large leaf-apposed tendril-bearing panicles.
Flower:
Small, yellowish-green, regular, bisexual, pentamerous, hypogynous.
Calyx:
Sepals 5, gamosepalous, cup-shaped, inferior.
Corolla:
Petals 5, petals cohering at their tips, and falling off as a cap.
Androecium:
Stamens 5, antipetalous, free. Prominent intrastaminal disc consists of 5 small glands which alternate with the petals.
Gynoecium:
Bicarpelliary, syncarpous, ovary bilocular, each loculus with 2 ovules; style thick; stigma circular, flat.
Fruit:
Globose, succulent berry, 2-celled containing 1-4 seeds.
Seeds:
Small with thick testa; endosperm oily.
Floral formula:
Morphology of tendril:
The tendrils have special morphological interest. The tendrils are situated opposite the leaves and are apparently extra-axillary; the tendril according to Eichler is the original apical metamorphosed part of the main axis which is pushed aside by the growth of the branches arising from the leaf axil; the branching is scorpoid cymose.
The branch terminates directly into tendril. The inflorescence occupies the same position as the tendril, it further proves that the entire axis is a pseudo axis; sometimes organs partly tendrilar and partly flower bearing occur.