Main Difference – Spores vs Seeds
Spores and seeds are reproductive structures of plants which germinate to produce a new organism of the same species. Some spores are developed into male and female germ cells. The ovule contains egg cell in flowering plants. It is developed into a seed. Spores are produced by non-flowering plants. Fungi also produce spores as their reproductive structures. Seeds are produced by flowering plants. The main difference between spores and seeds is that spores do not contain stored food resources and require more favorable conditions for the germination whereas seeds contain stored food in their endosperm, enabling them to germinate in harsh conditions as well.
This article explores,
1. What are Spores
– Definition, Structure, Characteristics
2. What are Seeds
– Definition, Structure, Characteristics
3. What is the difference between Spores vs Seeds
What are Spores
Spore is a reproductive unit of sexual or asexual reproduction, which is adapted for survival after its dispersal for an extended period of time under unfavorable conditions. They are produced by many plants, fungi, algae, and protozoa. Bacterial spores are resistance structures, which are used for the survival of bacteria under unfavorable conditions. They contain bacterial genomic DNA, surrounded by a thick cell wall.
Two types of algal spores are found: non-motile aplonospores and motile, zoospores. All the reproductive spores are unicellular and haploid. They are produced in the sporangium of a diploid sporophyte by meiosis. Some vascular plants are homosporous, producing spores of same size and type. Others are heterosporous plants, producing two types of Spores: megaspores and microspores. Spores germinate into new gametophyte by increasing the cell number by mitosis. Gametes are produced by the gametophyte. The fusion of gametes forms the zygote, which is then developed into the sporophyte.
Figure 1: Spores of the underside of a fern leaf
What are Seeds
Seeds are fertilized and ripened ovules which are used for sowing. An embryo is present per one seed, which is capable of developing into a plant by germination. Hence, the seed is a propagative plant structure, which is often found inside a fruit. Seeds are found in gymnosperms (naked seeds) as well as in angiosperms (enclosed seeds). Fruits are developed by angiosperms. They are an important development in higher plants in order to make the reproduction successful. Angiosperms’ seed contains three constituents: a seed coat, an embryo, and an endosperm. The embryo sac of angiosperms undergoes double fertilization, simultaneously developing an embryo and an endosperm. The embryo contains cotyledons, plumule, and radicle. The integuments of the ovule become the seed coat. Tegmen and testa are respectively the inner and outer seed coats. Hilum, micropyle, and raphe are the three characteristic markers found on the seed coat. The endosperm supplies nutrients to the developing embryo. Seeds are dispersed either by wind, water or animals. Seed dormancy synchronizes germination until the arrival of optimal conditions. It also allows the seeds to survive under unfavorable conditions. Seeds in different shapes and sizes are found even within the same plant species.
Figure 2: Phaseolus vulgaris seeds
Difference Between Spores and Seeds
Definition
Spores: Spores are reproductive cells, which are capable of developing into a new individual without fusion of another reproductive cell.
Seeds: Seeds are ripened ovules of a flowering plant.
Occurrence
Spores: Spores are produced by fungi and non-flowering plants.
Seeds: Seeds are produced by flowering plants.
Found in
Spores: Spores are found in the underside of the leaves of ferns and mosses as well as the gills of fungi.
Seeds: Most of the seeds are found inside a fruit.
Size
Spores: Spores are microscopic.
Seeds: Seeds are macroscopic.
Produced by
Spores: Spores are produced by meiosis of the sporophyte.
Seeds: Seeds are developed by mitosis from the ovules with fertilized egg cells.
Production
Spores: Spores are produced in large numbers.
Seeds: Seeds are produced in fewer numbers.
Reproduction Type
Spores: Spores are units of asexual reproduction. Some fungi sexually reproduce by spores as well.
Seeds: Seeds are units of sexual reproduction.
Types
Spores: Homosporous plants produce identical spores, and heterosporous plants produce large female spores and small male spores.
Seeds: Monocots produce seeds with a single cotyledon and dicots produce spores with two cotyledons.
Cellular Complexity
Spores: Spores are unicellular.
Seeds: Seeds are multicellular.
Ploidy
Spores: Spores are always haploid.
Seeds: Seeds are always diploid.
Mode of Dispersal
Spores: Spores are mostly dispersed by the wind and water.
Seeds: Seeds are dispersed by animals.
Requirement for Water
Spores: Spores require more water the germination.
Seeds: Seeds require less water for germination. Hence, they germinate more easily compared to spores.
Food
Spores: Spores do not contain reserved food.
Seeds: Seeds contain the endosperm, which stores nutrients for the growth of its embryo.
Survival of the Organism
Spores: Spores are less prone to survive in the environment compared to seeds.
Seeds: Seeds are more capable of surviving in harsh conditions.
Conclusion
Spores and seeds are units of asexual and sexual reproductions in organisms respectively. Spores are haploid and unicellular while seeds are diploid and multicellular. Since seeds are multicellular structures, they are differentiated into several parts: seed coat, embryo, and endosperm. Seeds coats are protective layers of the seed, protecting seed from dehydration and predation. Spores are also protected by a hard cell wall. The endosperm stores required nutrients for the development of the embryo. Therefore, seeds are capable of surviving under harsh conditions when compared to spores. Hence, the main difference between spores and seeds is based on the capability of each unit to survive under unfavorable conditions.
Reference:
1. Bailey, Regina. “Spores – Reproductive Cells.” ThoughtCo. N.p., n.d. Web. 12 May 2017. <https://www.thoughtco.com/spores-reproductive-cells-3859771>.
2. “Seed.” Merriam-Webster. Merriam-Webster, n.d. Web. 12 May 2017. <https://www.merriam-webster.com/dictionary/seed>.
3. “Seed.” Wikipedia. Wikimedia Foundation, 10 May 2017. Web. 12 May 2017. <https://en.wikipedia.org/wiki/Seed>.
Image Courtesy:
1. “Spores under a fern leaf” By kaibara87 – originally posted to Flickr as Spores (CC BY 2.0) via Commons Wikimedia
2. “Phaseolus vulgaris seed” (Public Domain) via Commons Wikimedia
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