Note on Structural Variation in Angiospermic leaf

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Shape of leaf

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Acicular: Elongated pointed needle-shaped leaf. Eg; Pinus

Linear: Elongated, narrow flattened leaf. Eg; Grasses, Zea Hays.

Lanceolate: Elongated sword-like leaf. Eg; Nerium

Elliptic: Ellipse shaped leaf. Eg; Psidium Gwasava (Gawa)

Cordate: Hard shaped leaf or leaf with a notched base and pointed apex. Eg; Piper betel.

Obcordate: Leaf with notched apex and rounded or pointed base. Eg; Bauhinia

Ovate: Egg-shaped leaf or leaf with the broad base and narrow apex. Eg; Hibiscus

Obovate: Leaf with broad apex and narrow or pointed base. Eg; Terminalia

Oblong: Elongated rectangular leaf. Eg; Musa( Banana)

Hastate: Arrowhead-shaped leaf. Eg; upper leaf of Brassica Campestris.

Lyrate: Lyre-shaped leaf or leaf with large terminal lobe and small lateral lobes. Eg; Brassica Campestris

Apex of leaf

Acute: Leaf with a pointed apex.

Obtuse: Leaf with rounded apex.

Accuminate: Leaf with pointed apex in which extreme apex is drawn out into an elongated tale like structure.

Mucronate: Leaf with rounded or pointed apex in which short pointed outgrowth appears at the extreme tip.

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Surface of Leaf

Glabrous: Leaf with a smooth or non-hairy surface.

Glaucous: Leaf with the smooth and shiny surface. Eg: Rubber plant.

Pubescent: Leaf with the hairy surface. Eg: Geranium

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Margin of Leaf

Entire: Leaf with the smooth margin.

Repand: Leaf with slightly or lightly wavy margin.

Sinuate: Leaf with deeply wavy margin.

Serrate: Leaf with a saw - like margin in which teeth are directed towards the apex.

Serrulate: Leaf with finely serrated margin.

Dentate: Leaf with toothed margin in which teeth are outwardly directed.

Runcinate: Leaf with a saw- like margin in which teeth are directed towards the leaf base.

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Texture of leaf

Herbaceous: Thin and soft textured leaf. Eg; Rose

Coriaceous: Thick firm and leathery texture. Eg; Rubber plant

Succulent: Thick and fleshy leaf which stores water in the form of mucilage. Eg; Aloe vera

Duration of leaf

Caducous: Leaves falling off much earlier in the life.

Deciduous: Leaves remaining intact at least for one season.

Persistent: Leaves remaining intact for whole life.

Insertion of Leaf

Cauline: Leaves arising on the main stem. Eg; Maize

Ramal: Leaves arising on the branches. Eg; All trees

Radical: Leaves arising in a cluster or in a rosette form from the reduced stem known as disc than it is known as radical leaves. Eg; Radish, Turnip.

Phyllotaxy

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The mode of arrangement of leaves on the node of the stem is known as phyllotaxy. It is of three types;

Alternate/Spiral

If single leaf arises on a node and leaves of adjacent nodes lie alternately to each other then it is known as alternate phyllotaxy. Eg; Tulsi

Opposite

If a pair of leaves arise on a node and lie opposite to each other than it is known as opposite phyllotaxy. If a pair of leaves on adjacent nodes occur on the same plane than it is known as superposed opposite phyllotaxy. If a pair of leaves on adjacent node lie perpendicular to each other than it is known as decussate opposite phyllotaxy.

Whorled:

If a cluster of leaves arises on a node then it is known as whorled phyllotaxy.

  • Leaf is a lateral dissimilar appendage of a plant body which arises in the node of stem and bears axillary bud in its axil. 
  •  Leaves arising in a cluster or in a rosette form from the reduced stem known as disc than it is known as radical leaves. Eg; Radish, Turnip.
  • The mode of arrangement of leaves on the node of the stem is known as phyllotaxy. 
  • If single leaf arises on a node and leaves of adjacent nodes lie alternate to each other then it is known as alternate phyllotaxy. Eg; Tulsi
  • If a cluster of leaves arises on a node then it is known as whorled phyllotaxy.

 

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