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Vegetative Parts

Morphology Of Angiosperm of Class 11

Root

  • The direct prolongation of radicle is called primary root, which grows vertically downward exhibiting positively geotropic and negatively phototropic mode of growth.
  • From primary root, secondary root arises endogenously as a lateral branch at an angle of 45° showing plageotropic mode of growth. From secondary root, tertiary root arises laterally but exogenously at an angle of 45°, showing ageotropic mode of growth. The fine endings of the branches of a root are called as rootlets.
  • The root and its branches fix the plant body, absorb water and minerals, and hold the soil particles.  

Stem

❒ The direct prolongation of plumule is called stem. It is the axis of the shoot. It is protected at its tips by an apical or terminal bud.

❒ Stem is differentiated into nodes and internodes. The node is a place on stem and its branches from where a leaf or a group of leaves arises, in the axil of which an axillary or lateral bud develops. The space in between two successive nodes is called internode.

  • The axillary bud may form a branch or may flower into a flower. The branch is also terminated into an apical bud and is differentiated into nodes and internodes. Nodes bear leaves and buds. Thus stem and branch are considered analogous organs as they have different origin but similar morphology and function. Branch and flower are regarded as homologous organs, having similar origin but different functions.
  • The stem and the branches perform some major functions such as mechanical support, conduction of sap and transportation of food.

Leaves

  • These are the lateral outgrowth of the stem and its branches, borne on their nodes.
  • The leaf has a stalk called petiole and a flat green expanded portion called leaf blade or lamina. Lamina has a mid rib, from which many veins arise.
  • Leaf is a photosynthesizing part and manufactures food. It is also meant for gaseous exchange and transpiration.

Vegetative Parts

Fig. Parts of a flowering plant

 

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