Question

When calyx and corolla are not distinguishable, then a member of their collective whorl termed as:
a. Perianth
b. Sepal
c. Petal
d. Tepal

Answer 1

Hint: All the petals together and collectively termed as the corolla of the flowers. Petals are the colored parts of the flower which helps in cross-pollination. The outermost whorl of the flower is known as sepal Collectively the sepals in the flower is known as the corolla. Morphologically, both of them are modified leaves.

Complete answer:
When calyx and corolla are not distinguishable, then a member of their collective whorl termed is referred to as the tepals. A tepal is the outer part of a flower (collectively the Perianth) that does not take part in sexual reproduction. A tepal is defined as the term when sepals and petals cannot be identified easily. So option D is correct.

The outermost whorl of the flower is known as sepal. Collectively the sepals in the flower are known as the corolla. Sepals are generally green in color. They are modified leaves that do not take part in reproduction. So option B is incorrect.

Petals are the colorful structure that surrounds the reproductive organs of the flower. They help in attracting insects for cross-pollination. They are morphologically modified leaves. So option C is incorrect.

The Perianth is a structure that forms by the fusion of collectively calyx and corolla surrounding the sexual organs, consisting of the calyx (sepals) and the corolla (petals). They are non-reproductive organs of the flower. It is formed when both of them are fused. So option A is incorrect.

Hence, the correct answer is option (D).

Note: Tepals are formed by the fusion of sepals and petals. These are common in monocotyledons, particularly the Liliaceae. In tulips, for example, both the whorls of the flower contain structures that look like petals. These are fused at the base of the flower to form one large, showy, six-parted structure (the perianth). If the perianth is non-green, then it is called petaloid. If green in color, then it is called sepaloid.