Question

The stem of Opuntia is
A. Phyllode
B. Phylloclade
C. Cladode
D. Bulbil

Answer 1

Hint: Opuntia is one of the most common cacti which is domesticated and grown all over the country today even though it is not native to our country. It is also called ‘the prickly pear’. It commonly grows in arid regions with a very little amount of rainfall as it is succulently adapted to store water.

Complete answer:
Let us look at each of the options given in the question and understand the difference between each of them. The first is the phyllode. It is good to know that anything with “phyll” has something to do with leaves. Phyllode is a modified petiole that has taken up the functions of the leaves. Phyllode is not exactly a stem modification. Phyllode is a petiole that is modified like a leaf. The leaves in the plants that contain phyllode are mostly reduced and the phyllode takes over the functions of the leaf. The examples for plants with phyllode are Acacia spp. and Daviesia spp.
Next is phylloclade. Phylloclade can be defined as a branch that is flattened and has taken up the functions of the leaf. It has multiple nodes and internodes. They are photosynthetic in function. The leaves are highly reduced. Examples are Opuntia, Casuarina, etc.
Next, we will talk about cladodes. Cladodes are the stem modifications in which the stems become flattened and assume the functions of the leaves. The leaves are either present as scales or highly reduced. Cladodes are seen in plants like Ruscus, Asparagus, etc.
Bulbil is small rounded structures that are formed on the axil of the leaves where flowers arise. They act like vegetative reproductive structures as they can fall off and form new plants. Eg: Agave, Glabba, etc.

So, the correct answer is B – phylloclade.

Note:
It can be noted that cladodes are a type of phylloclade but the number of internodes in cladodes are very less (one or two). Phylloclade arises in the axil of the leaf and a scar is left when it falls off. The leaves are spiny. Cladodes resemble leaves but the flowers can be seen on these structures.