Forms of Thalamus in Flower

 

  

• There are three types of form of thalamus as regard to the insertion of carpal in relation to the other floral organ. 

• On the basis of position of calyx , corolla and androecium with respect to ovary, flowers are described as hypogynous perigynous and epigynous

Hypogynous flower - 

• Thalamus is conical with gynoecium occupying the top position while other floral organ are borne  below it. 

• Ovary  is superior while other floral parts are inferior. Hypogynous condition is also called the Hypogyny. 

• Thalamus is free from the wall of ovary and thalamus is not expanded. 

• Sepals petals and  stamens are well spaced therefore all parts of gynoecium are visible. It can be seen in Mustard , Brinjal , China Rose ,Ranunculus.

Perigynous flower - 

• Thalamus is disk like  cup ike or flask like  which is free from the wall of ovary thalamus is expanded on both the side. 

• Sepals petals and stamen are  developed from the margins. 

• Gynoecium will be visible wholly  or partly depending upon the shape of the thalamus. 

• Gynoecium is situated in the centre and other parts of flower are located on the rim of thalamus at the same level. Ovary is half inferior.  The perigynous thalamus is of following types - 

• Disc shape - The thalamus is expanded and become flat like disc. Pea, Gram,  Plum etc.

Cup Shaped - 

• The thalamus is enlarged  and become cup like.

• The gynoecium is developed from the bottom.All floral organ form a rim of thalamus. It is found in Prunus and Preach

Flask shaped - 

• Thalamus is enlarged and margin turn towards the upper side and assume flask shaped thalamus.

• The gynoecium is developed from the bottom.All floral organ form a rim of thalamus. For example - Rose.

Epigynous flower -  

• The thalamus is  expand grow and enclose completely  the ovary and fused.

• The other parts of flower are arisen above the ovary.

• The ovary is inferior and other parts are superior . This condition is found in Sunflower, cucumber, Guava, apple etc.