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. 

• They are 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. 

• They develop at or above the level of ovary. Ovary is superior or half inferior.  The perigynous thalanus is of following types - 

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

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.

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  expanded and grow over the ovary and fused.

• Style and stigma are developed from the center while other parts are arisen from the rim.

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