3. Kingdom Plantae - part 05 - Angiospermae

 

3. Kingdom Plantae - part 05 - Angiospermae


Angiospermae (Angios : enclosed :vessel, Sperma : seed) :

  • Angiosperms are the most advanced group of flowering plants. 
  • In these plants the seeds are enclosed within the fruit i.e. ovary.
  • Angiosperms is a group of highly evolved plants, primarily adapted to terrestrial habitat.
  • They vary in size.
  • Angiosperms show heteromorphic alternation of generation in which the sporophyte is diploid, dominant, autotrophic and independent. 
  • The gametophytes (male orfemale) are recessive, haploid and dependenton the sporophyte.
  • Angiosperms are heterosporous.
  • Microspores (commonly called pollens) are formed in microsporangia (or anthers). 
  • They develop in highly specialized microsporophyll or stamens while megaspores are formed in megasporangia (or ovules) borne on highly specialized megasporophyll called carpel.
  • Besides the essential whorls of microsporophylls (Androecium) and megasporophylls (Gynoecium) there are accessory whorls namely calyx (sepals) and corolla (petals) arranged together to form flowers.
Do u know ?
  • Wolffia is the smallest Angiosperm, 1mm in size and Eucalyptus grows to over 100 meters.
Classificaion of Angiosperms :
  1. Dicotyledonae 
  2. Monocotyledonae 
1. Dicotyledonae : 

  • These plants have two cotyledons in their embryo. 
  • They have a tap root system and the stem is branched. 
  • Leaves show reticulate venation while the flowers show tetra or pentamerous symmetry.
  • Vascular bundles are conjoint, collateral and open type. 
  • Cambium is present between Xylem and Phloem for secondary growth. 
  • In Dicots secondary growth is commonly found.
  • e.g. Helianthus annus (sunflower), Hibiscus rosa-sinensis (China rose).

2. Monocotyledonae : 


  • These plants have single cotyledon in their embryo. 
  • They have adventitious root system and stem is rarely branched. 
  • Leaves generally have sheathing leaf base and parallel venation while the flowers are generally trimerous.
  • The vascular bundles are conjoint, collateral and closed type. 
  • In Monocots, except few plants secondary growth is absent. 
  • e.g. Zea mays (Maize), Sorghum vulgare (Jowar).

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