Question

Phylloclade is found in -
a. Opuntia
b. Cactus
c. Acacia
d. Ruscus

Answer 1

Hint: Phylloclade is a modified stem that is green to carry out photosynthesis and has a thick waxy coating to prevent transpiration.

Completed answer:
Phylloclades are flattened shoots and are considered as modified branches. They are flattened leaf-like branches and structures that are photosynthetic in nature. In this case the water is stored inside the tissues. The phylloclade is a type of branch modification in plants and bears multiple nodes and internodes are present. Phylloclades are capable of unlimited growth. In phylloclade, the stem modifies into a succulent green structure and if falls off, it leaves a scar. They generally function as leaves, which can undergo photosynthesis.

In Cactus, the phylloclade is flattened, reduced or gets modified as spines. This feature of phylloclade helps to cope up the extreme environmental conditions by reducing transpiration from the surface of the leaves. They are adapted for life in the dry, arid and xeric conditions and these modifications make up for as added advantage.

In Opuntia, leaves are reduced to spines and stems are modified to perform photosynthesis in the extreme dry conditions. Hence, both the options (a) and (b) are correct.

Additional information:
There are three types of stem modification. The aerial modification is the type of modification where the axillary bud modifies to form a highly sensitive structure which is called tendril. These are generally found in passiflora. Another type of modification seen is thorn, seen in citrus plants. Phylloclade is also a type of stem modification where the flattened leaf-like structures are formed, which helps in photosynthesis, examples are cactus opuntia.

Note: These types of modifications generally occur for various special functions like protection, adaptation and water or food storage due to the climatic conditions. Shoot and root both parts undergo several structural and functional modifications in these types of plants.