What is the Difference Between Capitulum and Hypanthodium?

The main difference between capitulum and hypanthodium lies in their inflorescence types and receptacle structures:

Capitulum:

1. It is a racemose inflorescence, where the main axis grows continuously, and flowers are present laterally on the floral axis.
2. The receptacle consists of a flattened disc or upright column and is open from above.
3. The receptacle does not become fleshy.
4. The flowers are well exposed.
5. An involucre occurs at the base.
6. Capitulum may be homogamous or heterogamous.
7. The flowers are generally bisexual.

Hypanthodium:

1. It is a cymose inflorescence, where the main axis does not grow continuously, and a flower is present terminally on the main axis.
2. The receptacle is flask-shaped and closed, except for a pore lined by scales.
3. The receptacle becomes fleshy.
4. The flowers are not exposed.
5. An involucre is absent.
6. Hypanthodium is always heterogamous.
7. It has three condensed cymes.
8. The flowers are unisexual and show a distinct distribution.

In summary, capitulum is a racemose inflorescence with an open, flattened receptacle, while hypanthodium is a cymose inflorescence with a closed, flask-shaped receptacle.

Comparative Table: Capitulum vs Hypanthodium

Here is a table summarizing the differences between capitulum and hypanthodium:

Capitulum is a type of racemose inflorescence, while hypanthodium is a type of cymose inflorescence. The receptacle in capitulum is a broad, flattened upright column that does not become fleshy, and the flowers are well exposed. In contrast, the receptacle in hypanthodium is flask-shaped, becomes fleshy, and the flowers are not exposed.