What is perisperm? Where does it locate?

Hint: It is a food storing seed tissue which is developed from the nucellus.

Complete answer:
Perisperm is a layer of nutritive tissue that surrounds the embryo of a seed. An ovule consists of three parts: the integument that forms the outer layer, the nucellus and the female gametophyte in its center.
The nucellus is the inner structure of the ovule that may develop into the perisperm that feeds the embryo. Perisperm is the remains of the nucellus in seeds and is a diploid tissue. The nucellus develops into the perisperm after the process of fertilization. It provides nutrition to the developing embryo and is formed at the micropylar end of the ovule.
Perisperm appears to be reddish and has a paper-like composition. It is found in some seeds like that of beet and black pepper, coffee, etc. This perisperm remains persistent after the egg fertilization, surrounding the sac on the outer side of the embryo of a seed of some flowering plants.
Perisperm is found only in certain families, and plants like Caryophyllaceae, Amaranthaceae, Portulacaceae, Zingiberaceae, etc., wherein the existing embryo sac in these families turns densely packed food materials within the seed. It surrounds the endosperm and is prominent in monocot seeds. They are normally dry, and the endosperm of the seeds generally absorb their nutrition.

Note: Seeds of angiosperms exhibit two types of food storing tissues, they art: Perisperm and Endosperm. Stored food is found in the seeds of the form of proteins, fats, and carbohydrates which is utilized during embryonic development of the seed. The endosperm is the most important food storing tissue in the seeds. It surrounds the embryo and provides nutrition in the form of starch, sometimes oils and proteins.