Homologous Organs in Plants

Introduction

The experiment titled “Homologous Organs in Plants” aims to investigate homologous organs in plants. Some plants and animals possess organs or parts that seemingly have a quite dissimilar appearance and perform different functions but have the same origin and anatomy. Such organs are called homologous organs. We have studied homologous organs in plants by taking examples like the tendrils of Passiflora and the thorns of Punica granatum, the tendrils of Vitis and thorns of Carissa, the tendrils of Cardiospermum halicacabum and the bulbils of Agave desmettiana, the scale leaves of Allium, and the spines of Opuntia.

Procedure

Study the morphology, origin and function of the following homologous structures in the given plant species.
Tendrils of passion flower and thorns of pomegranate.
Tendrils of Vitis and thorns of Carissa.
Tendrils of balloon vine and bulbils of Agave.
Scale leaves of onion and spines of prickly pear.

Observation

In Passiflora (passion), axillary buds are modified to form tendrils that help in support, and in Punica granatum (pomegranate), axillary buds are modified to form thorns that help in protection. The terminal (apical) bud of the Vitis vinifera (grapevine) gets modified into a tendril, which helps in climbing around the support, and in the Carissa plant, the apical or terminal bud gets modified into thorns for protection.

The floral buds of Cardiospermum halicacabum (balloon vine) are modified into tendrils that provide support to the plant for climbing, whereas the floral bud in Agave desmettiana is modified into a bulbil and helps in reproduction.

In Opuntia ficus-indica (prickly pear), leaves are modified into spines, which check the rate of transpiration and also protect the plants from herbivores, whereas the leaves in Allium cepa (onion) are modified to scale leaves for the storage of food materials.

In all the above examples, we can observe that all the organs have the same origin and anatomy but a dissimilar appearance and perform different functions, which indicates homology.

FAQs on Homologous Organs in Plants

Q1: What are homologous organs?

Answer: Homologous organs are structures that have a similar underlying anatomical structure or origin but may have different functions due to adaptations to their specific environments.

Q2: What is the major difference between homologous and analogous organs?

Answer: The main difference between homologous and analogous organs is in their evolutionary origin. Homologous organs have a common ancestral origin, while analogous organs do not share a common ancestor but have similar functions due to convergent evolution.

Q3: Explain homologous organs in plants with an example.

Answer: Tendrils of Passiflora and thorns of pomegranate are the best example of homologous organs. In Passiflora (passion), axillary buds are modified to form tendrils that help in support, and in Punica granatum (pomegranate), axillary buds are modified to form thorns that help protect.

Q4: Explain the homology of Opuntia and onion plants.

Answer: In Opuntia ficus-indica (prickly pear), leaves are modified into spines, which check the rate of transpiration and also protect the plants from herbivores, whereas the leaves in Allium cepa (onion) are modified to scale leaves for the storage of food materials.

Q5: Explain the homology of grapevine and Carissa plants.

Answer: The terminal (apical) bud of the Vitis vinifera (grapevine) gets modified into a tendril, which helps in climbing around the support, and in the Carissa plant, the apical or terminal bud gets modified into thorns for protection.