Question

Velamen is a tissue found in
a. Parasites
b. All epiphytes
c. Aerial roots of some orchids/vanda
d. Halophytes

Answer 1

Hint: Velamen is a specialised tissue found in the root cortex of the plants to protect the plants from the UV radiations. It also protects the vascular structure of roots and absorbs moisture from the atmosphere.

Complete answer:
Velamen tissue is found in the aerial roots of some orchids or vanda. Vanda is a genus in the orchid family orchidaceae. Velamen is a spongy, multiple epidermis that covers the roots of some epiphytic or semi-epiphytic plants, such as orchid species. Roots of epiphytic plants are also known as hygroscopic roots. They hang freely in the air and absorb moisture with the help of velamen tissue.

The velamen tissue of an orchid is the white or gray covering of aerial roots. It is many cell layers thick and capable of absorbing atmospheric moisture and nutrients.

The main function of this tissue lies in protecting the underlying cells against damaging UV rays. The velamen also protects vascular tissue in the root cortex protecting the root from transpirational water loss. In some plants it helps in adhering the plant to the substrate.

The velamen arises from the root tip by a division of special tissue. The dead cells of velamen diffuse with light and give it a grayish appearance and after absorbing the water, these dead cells become transparent and the whole velamen tissue appears green.

Hence, the correct answer is option (C).

Note: Aerial roots are the modifications of adventitious roots, and these roots are also known as Epiphyllous roots which arise from the margins of leaf lamina for vegetative propagation or reproduction.