Sporangium Definition

A sporangium (plural: sporangia) is the capsule structure belonging to plenty of plants and fungi, in i beg your pardon the reproductive spores room produced and also stored.

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All land plants undergo one alteration the generations to reproduce; the sporangium is borne ~ above the sporophyte, i m sorry is the asexual 2nd generation structure.

The bulk of sporangia create haploid spores v meiosis, although some room able to develop spores v mitosis.

Typically, the plants which build two varieties of gametophyte do so within different microsporangia and also megasporangia. These create microspores and also megaspores, which are functionally tantamount to the masculine (micro-) and also female (mega-) gametes. The term used to define this properties is heterosporous, and also it applies to some bryophytes (non-vascular plants, including liverworts, hornworts and also mosses), part lycophytes (lesser clubmosses, spikemosses and also quillworts), a few pteridophytes (ferns) and also the seed-bearing spermatophytes (angiosperms and also cycads). In some cases, both types of spore are produced within the very same sporangium.

On the various other hand, equisetophytes (horsetails) and also most bryophytes space homosporous; they create only one kind of spore in ~ the sporangia, i beg your pardon subsequently creates into a monoecious gametophyte, own both male and female organs.

Sporangia can be found at the advice or follow me the political parties of trunk or leaves. In the situation of fungi, the sporangia space usually discovered at the advice of the hyphae.

The sac containing the spores is often elevated by a lengthy stalk called a ‘sporangiophore’, and also is supported by a non-reproductive structure, i m sorry extends into the sporangium referred to as the ‘columella’. In fungi, the fungus may create the columella, or it can be formed of a material produced by the hold on which the fungus is growing.

The image shows the terminal sporangia discovered at the end of the lengthy sporangiophore called the ‘seta’ in a moss species

In the ferns, the sporangia are clustered into dense aggregations called ‘sori’, which show up as round dots ~ above the under next of the fronds. Whereas the sporangia the the lycophytes room on the upper side of the leaves or follow me the stems.

The photo shows the sori the a fern. Each of the round dots contains multiple sporangia.

The microsporangia of the angiosperms (flowering plants) develop within the anther that the stamen. The microspores produced within the microsporangia—of which there is frequently four per anther—eventually develop into pollen grains.

The Launching Fern Sporangia

Because plants room sessile, the process of reproducing have the right to be problematic as soon as it comes to reaching various other plants through which to breed. Rather than relocating themselves, they have progressed to use techniques which disperse the spores or pollen far from the parental plant.

In a big group of ferns referred to as the leprosporangiate ferns, the sporangia the ferns have emerged a catapult mechanism to ensure their broad dispersal.

The sporangium of the fern has actually a ring the cuboid-shaped cells approximately the outside dubbed the ‘annulus’’; each of the cells is filled v water, i m sorry is lost to evaporation when the atmosphere is dry. The loss of water reasons the cell to shrink as the volume inside the cabinet decreases.

As the row of cell shrinks, the annulus is forced to progressively move right into a backbend and straighten out in the contrary direction—similar to how one next of one accordion moves as the musician compresses the other side.

The change in the curvature of the annulus causes the sporangium to open at the ‘stomium’ and the spores end up being exposed.

The picture shows a chart of the leptosporangiate sporangium. The row of cells about the top and also left is the annulus, the two longer cells ~ above the right form the stomium, and the spores space in the center.

The an adverse pressure (approximately –9MPa to –20MPa) result from the loss of water in the cells causes ‘cavitation’, through which a bubble is formed within each of the cells. The generation of the internal cavity creates a sudden rise in the volume of the cell and the annulus springs earlier to around 30-40% of its preliminary place in 10 microseconds, propelling the spores together it go so—this is perhaps the fastest activity made in the shortest time ever before recorded in plants. The annulus then completes the cycle end the next few hundred milliseconds, making a complete return to its initial shape.

The sophisticated method of spore dispersal is commonly compared come the activity used in the functioning of middle ages catapults.


1. What is the term used to explain plants that develop only one form of spore? A. Homosporous B. Eusporangiate C. Heterosporous D. Microsporangia

Answer to question #1
A is correct. Homosporous plants develop only one form of spore, which offers rise come a monoecious gametophyte. Heterosporous plants develop two different species of micro and megaspores within the sporangium.

2. What is the role of the columella? A. To assistance the sporangium. B. To prosper the spores. C. to propel the spores. D.

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To support the sporangiophore.

Answer to question #2
A is correct. The columella support the rigidity of the sporangium by prolonging within that is base.