Structure, reproduction, life history and systematic position of Marsilea

1. Structure, reproduction, life history and
systematic position of Marsilea
Sankrita Gaonkar
Assistant Professor in Botany
sankrita002@gmail.com

2. Contents
• Systematic position
• Morphology
• Anatomy
• Reproduction
• References

3. Systematic position
Division – Pteridophyta
Class – Pteropsida
Order – Marsileales
Family – Marsilaceae
Genus – Marsilea

4. Distribution:
• About 53 species, cosmopolitan in distribution but abundantly found in
tropical countries like Africa and Australia.
• About 9 species have been reported from India.
Habitat:
• Hydrophytic – M. minuta, M. quadrifolia – submerged or partially out of
water
• Sporocarps – produced under water
• Some xerophytic spp. – M. rajasthanensis
• All species are rooted either in mud or soil

5. SPOROPHYTE
• Plant is sporophyte
• Differentiated into root, rhizome and leaves
Rhizome:
• Creep on surface like stolon or just below soil surface,
slender, dichotomously branched with distinct nodes and
internodes
• Is capable of indefinite growth in all directions –hence
occupy an area of 25 m or more in diameter.
• In aquatic species internodes are long while in xerophytic
species they are short.
• Usually from the upper side at nodes, the leaves are given
out while from their lower side, the roots.

6. Roots:
• The roots are adventitious, arising from the underside of the node of rhizome,
either singly or in groups.
• In some spp. roots are given out even from the internodes (M. aegyptiaca).
Leaves:
• Arise from upper side of rhizome alternatively, arranged in two rows
• Petiolate and compound
• Submerged plants have long, thin petiole – helps leaves to float
• Compound lamina divided into four leaflets of same size – quadrifoliate
• Reticulate venation – united near margin by loop veins
• At night pinnae fold upwards – circinate vernation

7. Anatomy
Rhizome
• Epidermis – thick walled, stomata absent
• Cortex – outer parenchymatous cells, middle
cortex (air cavities), inner cortex (some cells
contain tannin, other contain starch)
• Stele – amphiphloic siphonostele

8. Leaf:
• Epidermis – single layered upper and lower
• Mesophyll – differentiated into palisade and spongy parenchyma
• Vascular bundles – xylem surrounded by phloem

9. REPRODUCTION
• Vegetative and spore formation
• Vegetative – tubers – morphologically they are
modified side branches – contain food and are
surrounded by scale leaves
Spore formation
• It bears the special structures known as sporocarps
which contain micro and megasporangia in them
• The sporocarps may be oval or bean-shaped.
• In the earlier stages of its development it is soft and
green but later on it becomes sufficiently hard and
brown in colour.
• It is heterosporous
• The sporocarps are borne on short peduncles above
the base of the petiole

10. • consists of two equal halves, each containing mixed sori protected by
vertically elongated indusia forming soral sacs
• Megasporangium and microsporangium – in each soral sace
• Sporocarp wall decay by bacterial action – spores are liberated

11. Microspores
• globose in shape with small pyramid-like apex. Each spore shows a faintly
developed triradiate ridge.
• spore wall bursts and the antherozoids are liberated in the water.

12. Megaspore
• The megaspore is ellipsoidal and possesses a small projection at the anterior
end.
• The mucilaginous spore wall is quite thick around the megaspore
• It finally gives rise to the egg.

13. References
• Vashishta BR. 2010. Botany for degree students:
Pteridophytes. S. Chand & company ltd.
• https://www.biologydiscussion.com/botany/pteridophyta/anato
my-of-marsilea-with-diagram-pteridophyta/54448
• https://www.ewingdigital.com/text_content/115890918455eb7
9e0538f1c.pdf
• https://www.biologydiscussion.com/pteridophytes/marsilea-
habitat-external-features-and-reproduction/5323