Question

Opposite phyllotaxy is found in
(a) Calotropis
(b) Mangifera
(c) Hibiscus
(d) Quisqualis
(e) both (a) and (d)

Answer 1

Hint: The number of leaves from a node at a time and its alignment with respect to its adjacent leaves is the key to identify the type of phyllotaxy exhibited by the plant.

Complete step-by-step answer:
Phyllotaxy is composed of terms ‘phyllon’ meaning leaf and ‘taxis’ meaning arrangement, thus, it is the pattern of arrangement of leaves on the stem or its branches. Its purpose lies in the importance of proper sunlight availability to every leaf on the plant. Three types of phyllotaxy can be observed in nature ⎯ Alternate phyllotaxy, opposite phyllotaxy and Whorled phyllotaxy.
Calotropis and Quisqualis possess opposite phyllotaxy.

Additional Information:
In Alternate phyllotaxy, each node bears only one leaf while leaves of the adjacent nodes are roughly opposite to it. At a time and a plane, only one node with one leaf is visible. E.g. China rose, moss, Hibiscus, Mangifera.
In Opposite phyllotaxy, a single node bears two leaves opposite to each other. This phyllotaxy is further divided into :
-Opposite and superposed: In this situation, a pair of opposite leaves on a node lie in the same plane as the pair of leaves on its adjacent nodes. This creates a total of two rows of leaves on the stem when viewed from the top. E.g. Quisqualis (Rangoon creeper)
-Opposite and decussate: In this situation, A pair of opposite leaves on a node is at a right angle with respect to the pair of leaves on its adjacent nodes. This creates a total of four rows of leaves when viewed from the top. E.g. Calotropis
In whorled phyllotaxy, three or more than three leaves arise from a single node creating a bunch-like structure known as ‘whorl’. E.g. Blackboard tree (Alstonia scholaris)
So, the correct answer is ‘ both (a) and (d)’.

Note: A leaf is the main organ of photosynthesis and transpiration in the plants. The reason lies in the presence of chlorophyll and stomata which perform photosynthesis and transpiration respectively. While chlorophyll needs maximum exposure of sunlight to synthesise glucose or simply food, the stomata perform the exchange of gases as well as regulation of water loss according to the environmental conditions.