Non-essential floral organs without differentiation of calyx and corolla are called
(a) thalamus
(b) pedicel
(c) perianth
(d) lodicules

Hint: Accessory organs that are not distinct present on the swollen stalk of a flower called the receptacle that forms an envelope around stamens and pistils.

Complete step by step answer:
Generally, a typical flower consists of 4 whorls namely calyx, corolla, androecium, and gynoecium. They are arranged on a swollen end of a stalk or pedicel called the thalamus. In some flowers calyx and corolla are not distinct and are called perianth.

Additional information:
- In angiosperms, a flower is considered a reproductive organ.
- A flower consists of four layers that are arranged on the thalamus which is the swollen end of a stalk or pedicel.
- Thalamus is also called the receptacle.
- The four whorls of a flower are calyx, corolla, androecium, and gynoecium
- Calyx and corolla are accessory organs and androecium and gynoecium are the male and female reproductive organs respectively.
- If a flower contains both androecium and gynoecium they are called bisexual flowers and if a flower contain either androecium or gynoecium they are called unisexual flowers
- In some flowers accessory organs are not differentiated and are termed as perianth.
- If a flower has radial symmetry it is considered as an actinomorphic flower and if a flower has bilateral symmetry it is considered as the zygomorphic flower
So, the correct answer is ‘Perianth’.

Note:
- Other names for calyx, corolla, androecium, and gynoecium are sepals, petals, stamens, and carpels respectively
- Examples of actinomorphic flowers are mustard, datura, chili, and zygomorphic flowers are pea, Gulmohar, bean, and cassia.