Notes on Marsilea: Systematic Position, Morphology, Gametophyte and Life Cycle

Marsilea
Systematic Position:
Division: Filicocophyta
Class: Leptosporangiopsida
Family: Marsiliaceae
Genus: Marsilea
  • Species:M. hirsuta, M.rajastthanensis , M.vestita (Amphibious), M.quadrifolia
  • Habitat: Aquatic or semi aquatic habitats
Plant Body: 
  • The plant body is the sporophyte  differentiated into Creeping rhizome, root and leaves.
  • Creeping rhizome: Grows beneath the soil, highly branched with nodes and internodes. Roots and leaves arise from the nodes
  • Leaves: rhizome forms single leaf from a node. Leaf consisits of long petiole with pinnae at the tip
  • Function: photosynthesis
  • Roots arising from node
Other features: 
  • Heterosporous nature.
  • Leptosporangiate
Life cycle: Heteromorphic alternation of generation.
Gametophyte or Prothallus:
•Microspore produces male gametophyte & megaspore produces female gametophyte.
•Microspore are globular with cellulosic exine and intine
•Male gametophyte develops within the microspore wall and produces many spirally coiled multi-flagellated antherozoids which swims towards megaspore
•Megaspores are large in size with exine and intine
•Megaspores germinates within megasporangium forming female gemetophyte bearing archegonia and a basal enlarged prothallial cell.
•Water is essential for fertilization
•The young sporophyte remains attached to the megaspore for some time later falls to the ground and form roots and become independent
Vegetative Reproduction: Tubers which can withstand unfavorable condition
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