Stem modifications – Mnemonic


Stem modifications:

Food & suits of runners, stolen by ten thousand cunning people.

  • Food (tuber, rhizome, corm, bulb)

  • Sucker

  • Offset

  • Runner

  • Stolon

  • Tendril

  • Thorn

  • Cladode

  • Phylloclade


  1. Underground modification of stem.

For food:

They also act organ of perennation.

  • Tuber is a swollen end of an underground branch. It possesses eyes representing the nodes. At each node, there is buds and a scale leaf.

E.g., potato (Solanum tuberosum).

  • Rhizome: is a perennial fleshy underground stem having nodes & internodes and bears adventitious roots on the lower side.

E.g., ginger and turmeric.

  • Corm: is a short, thick swollen unbranched fleshy stem growing vertically in the soil, consisting of circular nodes, axillary buds, and adventitious roots.

E.g., Amorphophallus and Colocasia.

  • Bulb is an underground structure possessing a reduced stem and several fleshy scale leaves that are concentrically arranged around the terminal bud. Adventitious roots develop from the lower part of the reduced stem.

E.g., onion (Allium cepa), tulips, lily, and garlic.

  1. Aerial modification of stem:

For support:

  • Tendrils are slender spirally coiled structure developing from the axillary bud. They coil around support helping in climbing.

E.g., gourd, cucumber, pumpkin, watermelon, and grapevines.

For protection:

  • Thorns are woody, straight and pointed structures developing from the axillary bud.

E.g., Citrus, Bougainvillea.

  For photosynthesis:

  • Phylloclade: are flattened, green stems of plants growing in the arid region.

E.g., Opuntia, Euphorbia.

  • Cladode is green stems of limited growth usually one internode long, that take the function of leaves. True leaves are reduced into spines.

E.g., Asparagus, Ruscus.

  1. Sub-aerial modification of stem:

For vegetative propagation:

  • Runner: are narrow green horizontal branches developing at the base of erect shoots. They spread in all directions and bear a crown of leaves above and a tuft of roots below.

E.g., grass, strawberry, Oxalis.

  • Stolon: is a slender lateral branch arising from the base of the stem and after growing aerially for some distance arches downwards to touch the ground.

E.g., mint, jasmine.

  • Offset: is a lateral branch with short internodes. They bear a rosette of leaves above and a tuft of roots below at each node at the water level.

E.g., Pistia, Eichhornia.

  • Sucker: lateral branches develop from the underground part of the main stem they grow horizontally beneath the soil and then come out obliquely upward giving rise to leafy shoots.

E.g., banana, pineapple, Chrysanthemum.


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