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Saturday, 3 March 2012

HAUSTORIUM (haustoria): structure (microscopic view), formation and function.



It is wondering structure in plant kingdom. From primitive fungi to highly evolved angiosperms we can see this structure. It is a projection originated from normal tissue to get better nourishment from neighboring source. 
Haustorium



Haustorium has hypotonic cytoplasm compared to surrounding host tissue. Hence it helps to grab the nourishment by osmosis.
 Amazing fact here is, how can Haustorium maintain its hypotonic nature with its own tissue..??? 

Its size varies, in fungi it is nodule like structure just penetrates into the host tissue and sucks the required nutrition. In fungi, haustoria can be seen at the base of the mycelium where it is in contact with host tissue.



HAUSTORIUM IN HOST TISSUE 



HAUSTORIUM IN HOST TISSUE 


In higher plants (Gymnosperm onwards) haustoria are quite rare. In the embryos of Angiosperms we can see haustoria where the requirement of nutrition is more. Endosperm of the Cucumis shows beautiful Haustorium. It grows to a size that it uses to cross out the integument of ovary to grab the nourishment. In advanced plants, in embryogeny the micropylar end shows slightly bulged haustoria.




MICROSCOPIC VIEW OF HAUSTORIUM
(ITS OBSERVED IN ENDOSPERM OF CUCUMIS)

Formation of haustoria is shown in sequence.





Different views of haustoirum........






 Haustoria play an important role for the survival of the plant and some other organisms.

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