The main difference between perisperm and pericarp is that perisperm is the nutritive tissue that surrounds the embryo and is derived from the nucellus or integument of the ovule, whereas pericarp is the outer layer of the fruit that develops from the ovary wall after fertilization.
Seeds and fruits are important parts of plants that perform unique functions. Perisperm and pericarp are two distinct components of a seed and a fruit.
Key Areas Covered
1. What is a Perisperm
– Definition, Structure, Function
2. What is a Pericarp
– Definition, Structure, Function
3. Similarities Between Perisperm and Pericarp
– Outline of Common Features
4. Difference Between Perisperm and Pericarp
– Comparison of Key Differences
What is a Perisperm
Perisperm is the nutritive tissue that surrounds the embryo. It originates from the nucellus or the integument of the ovule. The ovule has three parts: the integument, the nucellus, and the female gametophyte. After fertilization, the nucellus develops into the perisperm, which provides nutrition to the embryo. Moreover, perisperm is a diploid tissue with a reddish colour. It has a paper-like composition. It’s important to note that perisperm is only present in certain families and plants like Amaranthaceae, Portulacaceae, Zingiberaceae, etc. In fact, it is present in seeds like beet and black pepper, coffee, etc.
Perisperm has cells that are rich in starch, proteins, oils, and other nutrients that are essential for the growth and development of the embryo. It is found between the testa and the embryo. Perisperm is the largest part of the seed of some species.
The main function of the perisperm is to provide nutrients to the developing embryo during germination. Perisperm is a more persistent source of nutrients that can sustain the embryo until it gains the ability to perform photosynthesis of its own.
Perisperm also helps in the regulation of seed dormancy. In some species, like coffee and nutmeg, perisperm contains substances that inhibit germination until the seed has been subjected to certain environmental conditions.
What is a Pericarp
Pericarp is the outer layer of the fruit that develops from the ovary wall after fertilization. There are three layers in the pericarp. They are exocarp, mesocarp, and endocarp. However, these three parts vary in thickness and texture depending on the type of fruit.
Exocarp, which is the outermost layer, is thin and smooth in certain fruits such as grapes and apples, whereas in fruits such as oranges and lemons, it can be thicker and rougher. There are pigments in the exocarp that give a characteristic colour to the fruits. For example, a red pigment is present in strawberries, whereas bananas have yellow pigments. Mesocarp is the middle layer located between the endocarp and the exocarp. It has a fleshy nature. It is the edible part of the fruit. But in certain fruits, the mesocarp is fibrous and is not edible. Meanwhile, endocarp is the innermost layer of the pericarp. It is very hard and has a woody nature like in coconut shells or soft and papery like in tomatoes. Additionally, endocarp helps in the dispersal and protects the seed from damage.
Pericarp acts as a barrier against diseases and pests. It also provides nutrients and moisture to the developing seeds. The composition and texture of the pericarp also have an impact on the nutritional value.
Similarities Between Perisperm and Pericarp
- Both perisperm and pericarp are important for the survival and propagation of the plant.
- Moreover, they play a role in protecting the seed from external factors that could damage it.
- Both perisperm and pericarp can vary in their composition and structure, depending on the type of plant and the specific seed.
Difference Between Perisperm and Pericarp
Perisperm is the nutritive tissue that surrounds the embryo and is derived from the nucellus or integument of the ovule, whereas pericarp is the outer layer of the fruit that develops from the ovary wall after fertilization.
The function of the perisperm is to act as a source of nutrients for the developing embryo, while the function of the pericarp is to protect the seeds and aid in their dispersal.
Composition and Structure
Perisperm is composed of starch, proteins, and other nutrients, while pericarp has three layers and it contains pigments that give colour to the fruit.
In brief, perisperm and pericarp are two structural components present in seeds and fruits. But there are structural differences among them. The main difference between perisperm and pericarp is that perisperm is the nutritive tissue that surrounds the embryo and originates from the nucellus or integument of the ovule, whereas pericarp is the outer layer of the fruit that develops from the ovary wall after fertilization.
1. “Graine de quinoa” By Pancrat – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Drupe fruit diagram” By Sarang – Own work based on: Drupe fruit diagram-eu.svg (Public Domain) via Commons Wikimedia