Question

Haustoria are
A. Epiphytic roots
B. Hygroscopic roots
C. Reproductive roots
D. Parasitic roots

Answer 1

Hint: In botany and mycology, haustorium refers to a rootlike structure that grows into or around another structure to absorb water or nutrients. It is an appendage or portion of a parasitic fungus (the hyphal tip). It performs a similar function. These are commonly seen in parasitic plants. These roots attach to another plant vascular structure for water and minerals.

Complete answer:
Option A- Epiphytic roots
Epiphytic roots are also known as 'hygroscopic roots'. They develop in some orchids which grow as epiphytes upon the trunks or branches of trees. They are seen hanging freely in the air. They absorb moisture with the help of special sponge-like tissue called velamen.

Option B- Hygroscopic roots
Hygroscopic roots absorb water from the atmosphere with specialized dermal tissue. They are found in Vanda. These are aerial roots that intake nutrient and water absorption like in other roots. They are also used as structure, to reach the surface and they function like regular terrestrial roots.

Option C- Reproductive roots
These are seen in corms, stem tubers, rhizomes, and stolons that undergo vegetative reproduction.

Option D- Parasitic roots
All parasitic plants have modified roots known as haustoria. They penetrate the host plant. They connect the host plant to the conductive system – either the xylem, the phloem, or both. Examples of parasitic roots are plants like Striga or Rhinanthus. That connects only to the xylem, via xylem bridges.

So, the correct option is 'Parasitic roots'.

Note: Example of Haustorica - In mistletoe or members of the broomrape family, the structure penetrates the host's tissue to draw nutrients from it. Microscopic haustoria penetrate the host plant's cell wall and siphon nutrients from the space between the cell wall and plasma membrane. They do not penetrate the membrane itself.