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Thursday, March 7, 2019

Modifications of roots and stems

Modifications of roots and stem

  •  Modifications of roots.
  • Modifications of the Tap roots.
  • Modifications of Adventitious Roots.
  • Modifications of roots on the basis of mechanical strength.
  • Modifications of roots on the basis of vital functions.
  • Modifications of the stem.

Modifications of roots 

 💙 Roots generally perform the function of absorption and conduction of water and minerals in plants.
💙 But uncertain conditions they undergo modification and perform functions other than the primary functions like storage, support, and respiration.

Modifications of Tap Roots

 a) Conical: upper part bulged and the lower part shows gradual tapering example Daucus Carota.

 b) Napiform upper part bulged but lower part shows abrupt tapering examples Brassica rapa ( turnip), Beta vulgaris ( chukandar).

c) Fusiform: Found upper and lower parts are tapering but the middle part is swollen. example Raphanus sativus (Raddish).
d) Tuberous: No definite shape as their is irregular buldging and tapering e.g. Mirabilis Jalapa (4 clock plant), Trichosanthes.

Modifications of Adventitious Root

 a) Moniliform:  Swollen alternatively to give a beaded appearance, thus also called beaded roots examples Vitis Vinifera (grapes), Sorghum, Dioscorea

 b) Tuberous Upper Irregularly swollen or bulged also known as storage roots example Ipomoea batatas (Sweet potato).

c) Fasciculated:  Cluster of rootlets swollen from top to bottom examples Asparagus, Dahlia.
d) Nodulose:  Tip of the root is bulged example Curcuma Amada (Haldi).
b) Annulated:- Most Root appears like a rope as it is formed of a number of discs placed one over other examples Ipecac.
 Modifications of roots on the basis of Mechanical Strength.
a Prop or Pillar roots: Arise from aerial branches go downwards and provide support examples Ficus Benghalesis, Pandanus.
⚈ IBG Kolkata is famous for Banyan trees i.e Ficus Bengalensis.

 bStilt roots upper Arise from the node present very close to the soil surface and provide mechanical support examples Zea Mays, Sorghum, Bajra, Saccharum Officinarum.

cRoot buttresses: Horizontal running roots arising from the base of the stem to provide support examples Rubber tree ( Ficus elastica).
dClimbing roots or Clinging rootsIn certain climbers having the weak stem, roots arise from the node and clasp around the support and thus helps in climbing examples Piper betle, Pathos (Money plant), Campsis etc..

dAdhesive rootsIn plants like ficus rapens , Hadera helix roots adhere to the support on account of their adhesive nature(adhesive discs).

Modifications of roots  on the basis of Vital Functions

a Pneumatophores: Knee or breathing or respiratory roots, come out of the soil and bear minute pores called as pneumatophores to carry out respiratory exchange of gases examples Mangrove plants like Rhizophora, Avicennia, Sonneratia etc.

 bNodulated Roots Such roots have spherical outgrowths called as nodules which contain Nitrogen-fixing bacteria examples Leguminous plants (pea).

cParasitic Roots:   Also called as sucking or Haustorial roots are used to absorb food and water from the host plant example Cuscuta.

dFloating Roots  Produced by aquatic plants, come out on the water surface to provide buoyancy and also carry out respiratory exchange of gases examples Utricularia, Jussiaea etc.
eContractile or Pulling Roots:  Such roots contract to bring corms in an appropriate position examples Saffron (crocus sativus belong to family Iridaceae), Allium Sepa (Onion).

fEpiphytic Roots:  Also called as sucking or Haustorial roots are used to absorb food and water from the host plant examples Cuscuta.

Modifications of the stem.
aStem Tendrils:  Slender, spirally coiled develop from axillary buds and help plants to climb examples Passiflora, Luffa, Cucurbita, Grape Vine etc.

 bStem Thorns  Woody, straight pointed structures which also develop from axillary buds and help in reducing transpiration, in addition, protect plants from browsing animals examples  Citrus, Bougainvillea, Hugonia etc.

cPhylloclades  Stem modified into flattened (Opuntia), or fleshy cylindrical (Euphorbia) structures that contain chlorophyll and perform photosynthesis.

dCladodes Green photosynthetic stems  with leaves modified reduced to scales or modified into spines examples  Ruscus, Asparagus etc 
This was all about the Modifications of roots and stems. I hope you will like this article and don't forget to share it !...

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