Have you ever looked at the underside of fern leaves (known as "fronds") and seen rolls of tiny, strange, brownish-coloured bumps? Or ever popped a giant puffball mushroom? Do you suffer from summer-time allergies? If you answered yes to any of these questions, chances are you have come in direct contact with some members of the very diverse family that makes up spores. Now, exactly what are spores? Spores are the main reproductive units for asexual reproduction in many kinds of bacteria, fungi, algae, and non-flowering plants.

Did You Know?
The Anthrax spores, made famous by the 2001 Anthrax Scare in the United States, are actually the dormant state of Bacillus anthracis, a rod shaped bacteria, and not a reproductive spore like the ones discussed above

Spores are also involved in the early stages of plant sexual reproduction.

Did You Know?
the term "spores" comes from the Greek word "spora" which means seed

Spore production occurs through a process called sporogenesis via either meiosis or mitosis.

In mitotic reproduction, the spore will contain the exact same genetic component of its parent organism, a form of self-cloning.

In most plant organisms, spores are produced through meiosis. Meiotic cell divisions give rise to gametes. These gametes are the units of sexual reproduction and can be either male or female. They eventually fuse with other gametes of the opposite sex to pollinate and create seeds. The seeds are enclosed in an energy reserve, also known as the endosperm or fruit which provides nutrients for the seed while it awaits the proper environment in which to grow.

Did You Know?
Although most spores are not designed for long-term survival, some organisms will produce dormant spores which can withstand extreme heat or draught.

Seed production requires the fusion of a male and a female gamete. Conversely, in certain algae and fungi, meiotic sporogenesis occurs to create mitospores — which can develop on their own into a new organisms after they are released from the parent organism. Mitospores can also be called reproductive spores, and are able to form organisms independent of other spores. Reproductive spores also lack the endosperm, which means they have very small energy reservoirs and are therefore less viable in harsh environments. However, this also means that they are less likely to be consumed by animals or insects as food.

To increase the chances of successful germination, asexual plants tend to produce spores in huge numbers. Luckily, spores require minimal energy and material to produce, making it possible for large numbers of them to be created.

Reproductive spores are spread to new environments in several ways. They can make use of environmental vectors such as wind or water, or can also be ejected into the external environment by the parent plant (think: puffball mushrooms). Spores can be classified based on their ability to move: while many are immobile and require external forces to move them from their origin to new environments, others are capable of locomotion.

Did You Know?
Not all spores are immobile, zoospores have flagella (tails) which they can use to propel themselves to more favourable environments

So the next time you see a cluster of mushrooms under a tree or mold growing in the back of your fridge, take a minute to appreciate the incredible reproductive technique which has allowed for such kinds of plant organisms to survive for so many hundreds of millions of years!

Learn More:

Learn through play! (A new VERY COOL computer game that uses the concept of spore reproduction to create an interactive biological world)

Green algae reproduction

Protists and fungi reproduction

What are fungi?

This answer was researched and written by Alice Zhao. Alice received her Honours BSc in Biology, Physiology and English from the University of Toronto and currently works as a clinical researcher in HIV studies in Toronto, Canada.

Alice Zhao

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