Question

In Calotropis, the phyllotaxy is
A.Alternate
B.Verticillate
C.Opposite and superposed
D.Opposite and decussate

Answer 1

Phyllotaxis in plants can be of either two types, opposite or alternate. As the name suggests, in the case of opposite phyllotaxy, the leaves are exactly opposite to each other. And if the successive leaves are present exactly to each other they are called opposite and decussate, and one example would be the Calotropis.

Complete answer:
Phyllotaxis is the term used to describe the phenomenon of leaf arrangement on the stems of the plant. Plants have evolved specific arrangements that are so accurate that they can be mathematically predicted.
Phyllotaxy of a plant can be of either two broad types, namely opposite and alternate. Opposite phyllotaxy is when two leaves emerge from the same node of the stem exactly opposite to each other. The opposite phyllotaxy can be of two types, decussate and superimposed.
Decussate refers to a condition where the second pair of opposite leaves are positioned exactly from the position of the first pair. Calotropis , Gardenia , Ixora are common examples of opposite and decussate phyllotaxy.
Superimposed as the name suggests is when the second pair is placed exactly above the first pair at the same angle, giving a visual of the leaves being superimposed on each other when viewed from the top.
Alternate phyllotaxy, or also known as whorled phyllotaxy, is where the leaves are placed at alternate positions of each other given a spiral-like view of the leaf arrangement. Some examples of plants that exhibit alternate phyllotaxy are Brabejum stellatifolium , rice, papaya, etc.

Therefore, the correct option is D. Opposite and decussate

Note: Phyllotaxis is the arrangement of leaves on the stem.
It is of two broad types, opposite or alternate.
Alternate phyllotaxis is also known as, whorled, spiral, or cyclic phyllotaxis.
Decussate is when the second pair of leaves are perpendicularly placed above the first pair of leaves. This is mainly seen in the case of opposite phyllotaxy.
Verticillate phyllotaxy, is a form of alternate phyllotaxy or whorled phyllotaxy where three or more leaves emerge from the stem node, instead of two. Examples of verticillate phyllotaxy are Nerium odorum and Alstonia scholaris.