Ranunculaceae

The Ranunculaceae family belongs to the Angiosperm division of the Plantae kingdom. These are commonly known as the buttercup or crowfoots family. These are primarily herbaceous, annual or perennial plants that grow in colder regions. These are vastly found in the Himalayan regions of Pakistan and India. The largest genera of the Ranunculaceae family are Ranunculus (600 species), Thalictrum (330 species), Delphinium(365 species), Clematis (325 species) and Aconitum (300 species). They have bisexual flowers that are actinomorphic and pentamerous, with no distinction of calyx and corolla, found in temperate and other colder regions of the world.

The species of Clematis are found in the Western Himalayas up to a height of 5,000 feet, and Thalictrum javanicum is distributed from Shimla to Sikkim hills and is also found in Khalsa hills in Assam. These plants mostly have simple leaves, but in Clematis, the leaves are compound.

In Clematis aphylla, the whole leaf is modified into tendrils. Its flowers are bisexual, mostly actinomorphic and pedicellate, with 5 sepals, 3-5 petals and numerous, free stamens. They mostly have a superior ovary with marginal placentation. Gynoecium is apocarpous with anatropous or hemitropous ovules.

Systematic classification by Bentham and Hooker

• Division: Phanerogrames
• Class: Dicotyledones
• Sub class: Polypetalae
• Order: Ranales

Morphological Characteristics

• These are predominantly herbs. Few of them are shrubs and very rarely they are also trees.
• These are perennial or annual plants.
• They exhibit perennation (the ability of plants to survive from one germinating season to another through rhizomes or by tuberous roots like in Aconitum). 
• The rhizomes or creeping root stalks are simple fleshy underground stems from the axillary bud. They act as a storehouse for proteins and starches, enabling the plants to perennate underground during unfavourable germinating conditions. 

Roots:

• They have tap root systems in the early stage of development, replaced by adventitious roots (roots that develop from any seed part other than radicle) later.

Stem:

• They have herbaceous, non-woody stems.
• Stems are positively phototropic, negatively geotropic, erect and branched.
• They have rhizomes or creeping root stalks in certain plants.

Leaves:

• They have simple leaves.
• They exhibit alternate or opposite phyllotaxy (arrangement of leaves on a stem).
• These are exstipulate (i.e. stipules, the leaf-like appendages borne at the petiole base are absent).
• Petioles are rarely sessile.
• Leaves have unicostate or multicostate venation.
• Ranunculus aquatilis, also known as white crowfoot, shows leaves dimorphism.

Flower:

• They are pedicellate (flower with a stalk).
• They are ebracteate (have no bracts).
• Flowers are mostly hermaphrodite or bisexual.
• Flowers are mostly actinomorphic, i.e. radially symmetrical, while Delphinium (commonly known as Larkspur) has zygomorphic or bilaterally symmetrical flowers.
• These are pentamerous.

Calyx:

• There is no distinction between calyx and corolla in most of the flowers.
• They have 5 sepals, caducous and polysepalous (sepals are free).
• They have imbricate or valvate aestivation.
• Perianth is dichlamydeous.
• Hypanthium (fusion of bases of petals, sepals and stamens) are absent. 

Corolla:

• It consists of 3-5 petals that are polypetalous, variously coloured to attract insects for pollination and caducous.
• In Delphinium, the petals are united to form a spur.

Androecium: 

• It consists of free, numerous spirally arranged stamens on the thalamus.
• Anthers are dithecous (two thecae), extrorse (anthers dehiscence towards the centre of the flower) and adnate (fusion of one or two whorls).

Gynoecium: 

• They are polycarpellary (1 in Delphinium and 3-5 in Aconitum).
• They are mostly apocarpous (distinct carpels or pistils).
• They have superior ovaries or hypogynous (i.e. ovary attached to the receptacle above the attachment of other floral parts).
• They mostly exhibit marginal placentation, while Nigella has axile placentation.

Fruits:

• The following fruits are found: Aggregate, etaerio of achenes in Buttercup, etaerio of follicles in Aconitum, also known as the queen of poison or devil’s helmet, etaerio of berry (Hydrastis) and simple pod in Xanthorhiza.

Seed:

• They have small, oily, endospermic seeds.
• They have two cotyledons that can be epigeal or hypogeal.

Pollination:

• Delphinium, Aconitum and Aquilegia are entomophilous; the transfer of pollen grains occurs with the help of insects, while Thalictrum is anemophilous (transfer of pollen grains occurs by the action of air currents).

Economic Importance Of Plants belonging to the Ranunculaceae Family

1. Condiments: Seeds of Nigella sativa (black cumin) are used as spices in pickles. The seeds mixed with sesame oil are used externally for skin eruptions and scorpion stings. The seeds are stimulant, carminative and diuretic.
2. Medicinal: Aconitum hyperphyllum yields several alkaloids, especially aconitine, which is used for the treatment of acute, inflammatory diseases. Roots of Thalictrum yield mamira, which is used to treat neonatal conjunctivitis or ophthalmia neonatorum. Cimicifuga racemosa gives the black snakeroot containing resins recommended for the treatment of cholera and nerve pain. Ranunculus aquatilis is used in the treatment of rheumatic pain and asthma.
3. Ornamental: Some plants are ornamental for their beautiful showy flowers. For example, Delphinium ajacis, Ranunculus ssp., Clematis, etc.

Phytochemistry

Ranunculaceae contain protoanemonin, which is toxic to humans and animals. When humans contact the plant sap, it may cause inflammation and blistering of the skin, while ingestion can irritate the mouth, vomiting and diarrhoea.

Conclusion

Ranunculaceae family, also commonly known as buttercup or crowfoots family, are considered to be the primitive family of Angiosperm division because of the following reasons:-

• They have a Predominantly herbaceous habitat.
• They have bisexual and actinomorphic flowers.
• They have anatropous ovules.
• They have follicular, aggregated fruits.

The Ranunculaceae family consists of 2,000 known flowering plants under the 43 genera. Ranunculus is the largest genera, with 600 different known species under it. These plants are majorly found in colder climates. Plants belonging to these families secrete poisonous or toxic compounds like alkaloids, glycosides and protoanemonin.