Various modification of leaves

  • Leaves of plants are modified to various structures for adaptation to the environment where they are present.
  • Some of the modifications are listed as below:

1)Leaf tendrils:

  • Tendrils are thread like sensitive structures, which can coil around a support to help the plant in climbing.
  • They are of following types:

i)Whole leaf tendrils: e.g., Lathyrus aphaca (wild pea).

ii)Leaflet tendrils: e.g., Pisum sativum (pea), Lathyrus odoratus (sweet pea).

iii)Petiolar tendrils: e.g., Tropaeolum majus (garden nasturtium) and Nepenthes.

iv)Rachis and petiolule (stalk of the leaflet) tendrils: e.g., Clematis.

v)Rachis tip tendrils: e.g., Lens culinaris (lentil).

vi)Leaf tip tendrils: e.g., Gloriosa superba (glory lily).

vii)Stipular tendrils: e.g., Smilax (kukurdiano).

2)Leaf spines:

  • The leaf part becomes changed into spines in order to protect the plant from grazing animals and excessive transpiration.
  • The different types of modifications are:

i)Stipules are modified into spines. E.g., Zizyphus, Acacia.

ii)Leaves of the main stem are modified into branched spines. E.g., Berberis.

iii)Normal leaves are ill developed and fall down very soon but small leaves of axillary buds are modified into spies. E.g., Opuntia.

iv)Apex as well as margin both are modified into spines. E.g., Aloe.

v)Margin of the lamina modified into spines. E.g., Argemone.

vi)Apex of the lamina modified into spines. E.g., Yucca and Phoenix.

3)Leaflet hooks:

  • In Doxantha (Bignonia unguis-cati) commonly called cat’s nail, three terminal leaflets of compound leaf are modified into sharp, pointed and curved hooks.
  • The hooks cling to the bark of the supporting tree and allow the plant to climb up.

4)Phyllode:

  • Phyllode is a green, flattened leaf like structure develops from petiole.
  • e.g., Acacia auriculiformis (Australian Acacia) and Parkinsonia.

5)Leaf bladders:

  • They occur in the aquatic carnivorous plants Utricularia (Bladderwort).
  • Some of the leaf segments are modified to form small bladders.
  • The bladder like structure traps insects for their nitrogen content.

6)Leaf pitchers:

  • The leaf blade of lamina is modified to form a large pitcher in pitcher plant (Nepenthes) for the purpose of capturing insects.
  • The pitcher is provided with a lid which itself is an outgrowth of the leaf apex.
  • The petiole is modified into a tendrillar structure to hold the pitcher in a vertical manner.
  • The non-carnivorous pitcher plant is Dischedia.

7)Scale leaves:

  • These are small, dry, membranous brown or white leaves found in Casuarina and Ruscus.

8)Succulent leaves:

  • The leaves are green and fleshy which store water or food materials.
  • g., Aloe, Agave, Bryophyllum, etc.

9)Coloured leaves:

  • In Euphorbia pulcherrima (lalu pate), the leaves borne near the cyathia are brightly coloured to attract insects for pollination.

Various modification of leaves

 

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