Question

Velamen is found in

• A. Vanda
• B. Rosa
• C. Viscian
• D. Santalum

Answer 1

The correct option is A Vanda

Velamen is a spongy, multiple epidermis that covers the roots of some epiphytic or semi-epiphytic plants, such as orchid and Clivia species. The velamen of an orchid is the white or gray covering of aerial root. It is many cell layers thick and capable of absorbing atmospheric moisture and nutrients. Often, the roots of orchids are associated with symbiotic fungi or bacteria. The latter may fix nutrients from the air. This functionality allows the orchid to exist in locations that provide a reproductive or vegetative advantage such as improved exposure or reduced competition from other plant species.
The velamen also serves a mechanical function, protecting the vascular tissues in the root cortex, shielding the root from transpirational water loss, and, in many cases, adhering the plant to the substrate. Vanda is an epiphytic orchid which usually grows on branches of other trees. It does not take any food, water or minerals from the host tree but grows on the branches to get the firm support so as to get maximum sunlight in a thick forest where sunlight does not reach on the ground.

Velamen tissue from the roots are nothing but the parenchymatous cells which are loosely arranged and they are capable of absorption of water vapour directly from the atmosphere. With the help of this water, the green leaves of Vanda can synthesise its own food and survive. Velamen is absent in Rosa, Viscin and Santalum.
Thus, the correct answer is option A.