Family – Ranunculaceae
🌿 Family – Ranunculaceae | Scientific Identification, Morphology, and Importance
Scientific Identification:
- Kingdom: Plantae
- Clade: Angiosperms
- Order: Ranunculales
- Family: Ranunculaceae
Diagnostic Features (Identification)
Ranunculaceae is recognized as one of the most primitive families among flowering plants. It includes around 35 genera and approximately 1500 species.
The plants of this family are typically found in the cold regions of the Northern Hemisphere, including Europe, North America, and Russia. In India, many species occur in the outer and middle ranges of the Himalayas and hilly regions. Notable genera found in India include:
- Ranunculus
- Aconitum
- Caltha
- Thalictrum
- Anemone
Habit
Most plants in the Ranunculaceae family are herbaceous, commonly annuals, such as:
- Ranunculus sceleratus
- Delphinium ajacis
- Nigella sativa
Due to the presence of rhizomes or tuberous roots, some species are perennials, like:
- Helleborus
- Cimicifuga
- Aconitum
Some genera show climbing or trailing habits, e.g.:
- Clematis (with petiole-like tendrils)
- Naravelia (with true tendrils)
Some Ranunculus species are aquatic, such as:
- R. lingua
- R. equisetifolius
- R. flammula
In genera like Thalictrum and Actaea, the vascular bundles are scattered as in monocot stems.
Leaves
- Usually alternate
- Blade is simple or palmately lobed
- Stipules generally absent
- The leaf base may be sheathing
Some genera like Thalictrum, Caltha, R. ficaria, Coptis show stipule-like structures.
In Clematis, the leaves are opposite and compound. In Naravelia, 3–5 leaflets are present, with the terminal leaflet modified into a tendril.
Clemetis aphylla is remarkable because the entire leaf transforms into a tendril, and photosynthesis occurs in the stem.
In R. aquatilis, a water-growing species, dimorphic leaves occur. In Anemone, leaves arise from the base (radical).
Inflorescence
- Solitary terminal flowers are seen in Anemone and Nigella
- Dichasial cymes in Ranunculus and Clematis
- Racemose in Delphinium and Aconitum
- Nigella shows a whorl of leaf-like bracts beneath the flower
Flower
- Actinomorphic in most (Ranunculus, Aquilegia)
- Zygomorphic in Delphinium, Aconitum
- Hypogynous, pentamerous, often with a convex thalamus
- In Nigella, thalamus is elongated
Perianth
In most cases, there is no clear differentiation between calyx and corolla. However, in exceptions like Ranunculus, Delphinium, Aconitum, and Aquilegia, distinct sepals and petals exist.
- Perianth members range from 5–15
- Colored like petals (Caltha genus)
Primitive flowers of Ranunculaceae show three parts:
- Perianth
- Androecium (sometimes modified into nectaries)
- Gynoecium
In Clematis, only 4 white perianth parts are present with valvate aestivation.
In Ranunculus, Aconitum, Delphinium, flowers show imbricate or quincuncial aestivation:
- Two petals fully outside
- Two fully enclosed
- One with half outside and half inside
In Delphinium, the posterior sepal is spurred.
Corolla (Petals)
- Present in genera like Ranunculus, Aconitum, Delphinium, Aquilegia
- In Delphinium, two posterior petals unite to form a hood-like spur
- In Aquilegia, all five petals are spurred
- In Ranunculus, each petal contains a nectary gland at its base
In Helleborus, Cimicifuga, Actaea, nectaries replace petals. Nigella contains around 8 nectaries.
Androecium (Stamens)
- Numerous, free, spirally arranged
- Stamens are dithecous, extrose, basifixed
- Typically arranged in 13 radial whorls (but variable)
Gynoecium (Carpels)
- Carpels are usually free, superior
- In Nigella, 4–8 carpels are syncarpous and multi-locular
Placentation:
- Axile in syncarpous ovary (e.g., Nigella)
- Basal or marginal in unicarpellary ovaries
- Ranunculus shows pendulous ovules
- Anemone may have aborted ovules
- Delphinium and Helleborus have two rows of ovules
Stigma is:
- Hook-like in Ranunculus
- Feathery in Clematis and Anemone
Pollination
Due to:
- Brightly colored flowers
- Nectar presence
- Attractive petals
…flowers attract insects, leading to entomophily (insect pollination).
As most flowers are protandrous, cross-pollination is common, but self-pollination may occur if cross-pollination fails.
Fruit
Variation in gynoecium structure leads to different fruit types:
- Aggregate of achenes in Ranunculus, Clematis, Anemone
- Aggregate of follicles in Delphinium, Aconitum
- Septicidal capsule in Nigella
- Berry in Actaea
Dispersal adaptations:
- Clematis and Anemone have persistent, feathery styles aiding in wind dispersal
- Ranunculus has hooked styles that attach to animals for zoochory
Seed
- Seeds are rich in oily endosperm
- Endosperm is much larger compared to the embryo
Economic Importance of Ranunculaceae
Many members of the Ranunculaceae family are important medicinal and ornamental plants.
| Plant | Use | Location |
|---|---|---|
| Ranunculus sceleratus (Larkspur) | Medicinal, Ornamental | Found in temperate regions, Himalayan belt |
Example: Larkspur (Ranunculus sceleratus)
- Habit: Annual herb
- Root: Tuberous
- Stem: Aerial, erect, cylindrical, hollow, green
- Leaf: Simple, palmate, dissected, petiolate, reticulate venation
- Inflorescence: Racemose (definite type)
- Flower: Complete, bisexual, pedicellate, bracteate, bracteolate, violet color, hypogynous
Perianth:
- Sepals: 5, free, violet, posterior one spurred
- Petals: 4, united, two small posterior petals forming a spur
- Stamens: Numerous, free, arranged in rings, flattened filaments, basifixed anthers
- Carpels: Apocarpous, superior, unilocular, hairy ovary, marginal placentation
- Fruit: Follicle
Floral Formula:
Br, Brl, ⚥ K₅, C(₄), A∞, G₁̲
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