Modifications of Stem: Plants need to perform different functions to survive in changing environmental conditions and protect themselves from being damaged by other organisms. Modification of the stem is a natural phenomenon seen in plants and helps them to meet different needs. Stem gets modified to form different structures that in turn perform different functions.

Types of Modifications of Stem

• Modification for food storage 
  Underground stems of potato, ginger, turmeric, zaminkand, Colocasia are modified to store food in them. They also act as organs of perenation to tide over conditions unfavourable for growth.
• Modification for support 
  Stem tendrils which develop from axillary buds, are slender and spirally coiled and help plants to climb such as in gourds (cucumber, pumpkins, watermelon) and grapevines.
• Modification for defense 
  Axillary buds of stems may also get modified into woody, straight and pointed thorns. Thorns are found in many plants such as Citrus, Bougainvillea. They protect plants from browsing animals.
• Modification for photosynthesis 
  Some plants of arid regions modify their stems into flattened (Opuntia), or fleshy cylindrical (Euphorbia) structures. They contain chlorophyll and carry out photosynthesis.
• Modification for vegetative propagation
  • Runner – Underground stems of some plants spread to new niches and when older parts die new plants are formed. e.g., grass and strawberry
  • Stolon – In these plants a slender lateral branch arises from the base of the main axis and after growing aerially for some time arch downwards to touch the ground. e.g., mint and jasmine
  • Offset – A lateral branch with short internodes and each node bearing a rosette of leaves and a tuft of roots is found in aquatic plants. e.g., Pistia and Eichhornia.
  • Sucker – in these, the lateral branches originate from the basal and underground portion of the main stem, grow horizontally beneath the soil and then come out obliquely upward giving rise to leafy shoots. e.g., banana, pineapple and Chrysanthemum

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By Team Learning Mantras