Difference Between Spore and Seed

The key difference between spore and seed is that spore is a unicellular microscopic structure while seed is a multicellular macroscopic structure.

Spore and seed are two reproductive structures. Both spore and seed should germinate in order to produce a new organism. When comparing seed and spore, spores are microscopic while seeds are macroscopic. Moreover, seeds are multicellular while spores are unicellular. Thus, there is a significant difference between spore and seed in terms of both structure and function.

CONTENTS

1. Overview and Key Difference
2. What is a Spore 
3. What is a Seed
4. Similarities Between Spore and Seed
5. Side by Side Comparison – Spore vs Seed in Tabular Form
6. Summary

What is a Spore?

Spore is a unicellular microscopic reproductive structure that can develop into a new individual. Depending on the different types of spores, a plant can be either homosporous or heterosporous. Homospory refers to plants that have only one type of spores, while heterosporous refers to plants with two types of spores: male spores (microspores) and female spores (megaspores).

In angiosperms, microspores are pollen grains and they are found inside the pollen sac or the microsporangium. Microspores are very small, minute structures. They are almost like dust particles. Each microspore has one cell and two coats. The outermost coat is the extine, and the inner one is the intine. Extine is a tough, cutinized layer. It often contains spinous outgrowths. Sometimes it can be smooth, as well. The intine is smooth, and it is very thin. It is mainly made up of cellulose. The extine contains one or more thin places known as the germ pores through which the intine grows out to form the pollen tube. The pollen tube elongates through the gynoecium tissues carrying two male gametes in it. In flowering plants, the megaspore mother cell divides meiotically, forming a tetrad of four megaspores in which the upper three megaspores degenerate.

What is a Seed?

After fertilization, the ovule develops into the seed. The two integuments of the ovule become the two seed coats: outer seed coat (testa), and inner seed coat (tegmen). Some seeds contain only one seed coat.

The stalk of the seed originates from the funicle. The nucellus is generally used up completely, but in some seeds, it may remain as a thin layer. The egg cell, after fertilization, gives rise to the embryo, and synergid and antipodal cells get completely disorganized after fertilization.

What are the Similarities Between Spore and Seed?

• Plants produce both spores and seeds.
• Both can develop into a new individual.

What is the Difference Between Spore and Seed?

Spore and seed are two reproductive structures that can develop into a new individual. Spore is a unicellular microscopic structure while seed is a fertilized ovary which is macroscopic. Therefore, this is the key difference between spore and seed. Furthermore, spores are haploid while seeds are diploid.

Moreover, an additional difference between spore and seed is that the spores do not contain embryos inside, whereas the seed contains an embryo inside. Besides, the microspores are minute dust-like particles whereas seeds are comparatively larger. So, the size also contributes to a difference between spore and seed.

Summary – Spore vs Seed

Spores are reproductive cells that can develop into new individuals without fusion of another reproductive cell. Moreover, they are microscopic unicellular structures. In contrast, seed is a fertilized ovule of gymnosperms and angiosperms. In angiosperms, seeds are found inside the fruits. Furthermore, gymnosperms produce naked seeds. When comparing the sizes of spore and seed, seeds are large while spores are microscopic. Furthermore, spores do not contain stored foods, while seeds contain stored foods. Thus, this is a summary of the difference between spore and seed.

Reference:

1. “Spore.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 7 Feb. 2019, Available here.

Image Courtesy:

1. “Morelasci” By Peter G. Werner – Own work (CC BY 3.0) via Commons Wikimedia
2. “Maryland senna seed” By Justin Meissen (CC BY-SA 2.0) via Flickr