Hypanthodium

In different plants, the way the flowers are arranged is different. The arrangement of flowers on the floral axis of a plant is referred to as inflorescence. There are three types of inflorescence:

• Racemose – indeterminate or indefinite
• Cymose – determinate or definite
• Mixed

Hypanthodium is a special type of cymose inflorescence.

Cymose inflorescence

The cymose inflorescence is when the apical growth of the floral axis ends with the formation of a flower. This inflorescence is also referred to as determinate or definite inflorescence. Here, the terminal flowers are the oldest while the young flowers can be seen on the lower side, and this is a basipetal arrangement. The rachis in this type of inflorescence is terminated by a flower bud at a very early stage,and the following buds gradually develop towards the lower side of the axis.

Cymose inflorescence, in turn, can be of the following four types:

• Solitary (example – Hibiscus rosa-sinensis of Malvaceae)
• Monochasial Cyme or Uniparous Cyme or Monochasium (example – Hamelia patens of Rubiaceae)
• Dichasial Cyme or Biparous Cyme or Dichasium (example – Nyctanthus arbor-tristis of Oleaceae)
• Multiparous Cyme or Polychasial Cyme or Polychasium or Pleiochasium (example – Calotropis procera of Asclepiadaceae)

Apart from these, there are special types of cymose inflorescence:

• Verticillaster (example – Leonurus sibiricus of Lamiaceae )
• Cyathium (example – Poinsettia pulcherrima)
• Hypanthodium (example – Ficus cunia and banyan)
• Coenanthium (example – pick-aback plant, Dorstenia cordifolia of Moraceae)

Hypanthodium Inflorescence – What is Hypanthodium?

The receptacle in this type of inflorescence becomes spherical, like a hollow-sphere (syconium) with a cavity inside, and it is formed by the fusion of the rachis of the three cymes in the vicinity of each other. These spherical receptacles are like a closed fleshy vessel having a tiny opening at the apex; it opens to the exterior with this opening.

There are several small, sessile flowers that are produced from the inner surface of the receptacle. Three types of unisexual flowers are seen arranged on the inner surface of the receptacle in the cymose groups. They are – male, sterile female and fertile female flowers.

Hypanthodium Flowers

These are flask-shaped fleshy receptacles, possessing narrow canals with a terminal pore seen at one end. The pore can be surrounded by some scales, while the canal is lined by hair that is pointed downwards. The receptacles internally have male flowers towards the pore, while the female flowers are seen towards the base.

The neutral, sterile or gall flowers can be occurring between the two groups. There is a formation of an inflorescence of these three types of flower-bearing axes.

Hypanthodium Inflorescence Example – Hypanthodium Example

Examples of Hypanthodium Inflorescence

Hypanthodium is a special type of cymose inflorescence. The Hypanthodium inflorescence is found in the genus Ficus of the family Moraceae, e.g., Banyan (Ficus bengalensis), Peepal (Ficus religiosa), and Fig (Ficus carica).

Cyathium

Another special type of inflorescence is cyathium. In this inflorescence, the brackets unite, forming a cup-shaped structure. A few secretory glands are formed on the margin or the periphery of the cup. The female flowers in this cup are surrounded by a huge number of male flowers, while the male flowers are with brackets.

This specialized cymose inflorescence appears as a single flower. The axis gets suppressed, forming a convex receptacle. The centre of the receptacle exhibits a long-stalked and naked female flower having a tricarpellary gynoecium. This is surrounded by a vast number of male flowers organised in a scorpioid cyme.

The male flowers comprise a single stamen associated with a short stalk – the pedicel, wherein each one goes on to develop in the axil of the hairy bracteole. The complete inflorescence is wrapped by a cup-shaped green involucre which is formed by the fusion of bracts. The involucre is with one or two nectar glands on their outer walls, or usually with no gland. Flowers develop in the centrifugal fashion – the inner side to the exterior.

This type of cyathium inflorescence can be seen in Poinsettia pulcherrima and even in some members of Euphorbiaceae.

Difference between Cyathium and Hypanthodium

Cyathium

The cupular structure seems to be developed by an involucre of bracts. There is one female flower at the centre, which is engirdled by several stalked male flowers. A single stamen represents each flower. This type of inflorescence can be seen in Euphorbia.

Hypanthodium

The main axis develops in the cupular receptacle in an apical opening found at the apex. Both the male and female flowers can be seen on the interior walls of the cavity, which is enclosed in the cupular structure. This type of inflorescence can be seen in Ficus.

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Also see:

• What are the Types of Cymose Inflorescence?
• What is Racemose inflorescence?
• Comparison Between Staminate and Pistillate Flowers