Which of the following structures is well-developed in a mature seed of black pepper ?

The correct answer/option is Perisperm.

Step-by-Step Explanation:

1. Understanding Perisperm:
In most angiosperm seeds, the nutritive tissue known as the nucellus is completely consumed by the developing embryo sac and endosperm during seed development. However, in certain plants, a portion of this diploid maternal nucellar tissue persists and remains as a prominent, nutritive storage tissue surrounding the endosperm. This persistent, residual nucellus in a mature seed is called the perisperm.

2. Occurrence in Black Pepper:
Black pepper (Piper nigrum) is a classic botanical example where the nucellus is not fully consumed. Instead, it develops into a prominent, well-defined perisperm that acts as the primary food-storing tissue in the mature seed.

3. Analyzing the Other Options:
- Thalamus: This is the receptacle or modified stem tip that bears the floral parts, not a structure found inside or well-developed as a part of a mature seed.
- Sepals: These are the outermost green leaf-like structures of a flower (calyx) that protect the bud. They are generally shed or remain withered outside the fruit, rather than being a well-developed structure inside the seed.
- Peduncle: This is the stalk that supports an entire inflorescence or a solitary flower/fruit, not a seed-internal structure.

Therefore, the perisperm is the correct structure that is well-developed in the mature seed of black pepper.