John Miller
Basidia are microscopic, spore-producing structures found on the basidiocarp (mushroom, fruiting body, basidioma) of basidiomycete fungi. They are club-shaped and bear external meiospores, usually four, called basidiospores. The basidiospores are supported by short, pointed stalks called sterigmata. The basidia of many mushrooms produce four sterigmata and four spores, but some jelly fungi can produce eight or more spores per basidium. The lifecycle of a basidiomycete alternates generation with a prolonged stage in which two nuclei (dikaryon) are present in the hyphae.
| Characteristics | Values |
|---|---|
| Definition | A basidium (pl.: basidia) is a microscopic spore-producing structure found on the hymenophore of reproductive bodies of basidiomycete fungi. |
| Shape | Club-shaped, narrow at the stem and wide near its outer end. |
| Number of spores | Usually four, but can vary from two to eight. |
| Spore expulsion | Basidiospores are usually forcibly expelled from the basidium through changes in surface tension or electrostatic charges. |
| Spores attachment | The attachment of the sterigma to the apiculus of the basidiospore is broad and square. |
| Symmetry | Basidiospores that are not forcibly discharged tend to be radially symmetrical, while forcibly discharged spores are bilaterally symmetrical. |
| Stipe attachment | Basidiomycete taxonomy includes the morphological characteristic of stipe attachment. |
| Veil tissue | Veil tissue, or tissue covering the hymenophore, is another morphological characteristic of basidiomycetes. |
| Hyphal elements | Microanatomy of unique hyphal elements, such as oil-filled hyphae and sterile cells associated with basidia, is also a taxonomic feature. |
| Staining reactions | Staining reactions with certain chemical reagents, such as yellowing of the mushroom cap in potassium hydroxide, are useful traits for identification. |
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What You'll Learn
Basidia are microscopic, spore-producing structures
Basidia are club-shaped, normally narrow at the stem and wide near their outer end. They are widest in the middle hemispherical dome at their apex, and their base is about half the width of the widest diameter at the highest point. Basidia with a short and narrow base are shaped like an inverted egg, and occur in genera such as Paullicorticium, Oliveonia, and Tulasnella. Basidia with a wide base are often shaped like a barrel.
Basidia usually bear four sexual spores called basidiospores, which are produced at the tip of a narrow prong or horn called a sterigma. The number of spores can vary from two to eight. Each basidiospore grows from the tip of a sterigma that projects from the basidium. The basidia of many mushrooms produce four sterigmata and four spores, while some jelly fungi can produce eight or more spores per basidium.
Basidiospores are usually forcefully ejected from the basidium, although they do not travel very far, usually clearing the sterigmata by only a few micrometers. They are then at the mercy of wind currents, and because of their small size and lightness, they may travel great distances before settling. The mechanism of basidiospore discharge is thought to involve minute changes in surface tension or electrostatic charges associated with a small drop on the sterigma just below the point of spore attachment.
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Basidiospores are ejected forcibly from the basidium
Basidiospores are the sexual spores of fungi that form in the club-shaped basidium, the reproductive organ of the fungus. The basidiospores are perched on top of the basidium, which is usually contained within the mushroom. The basidiospores are supported by short, pointed stalks called sterigmata.
Basidiospores are forcibly ejected from the basidium in most cases. This forceful expulsion is due to a sudden change in the centre of gravity of the discharged spore. The basidiospores catapult themselves into the air. The propulsive force is derived from several factors, including Buller's drop, a drop of fluid that builds up at the tip of the basidiospore. This droplet grows and fuses with the meniscus of water around the top of the spore, causing the centre of gravity to shift dramatically and the spore to break off of the sterigma. The basidiospores are then shot into the free space between the mushroom's gills or pores, allowing them to fall out of the cap. This process is known as active dispersal, where the spores are also called ballistospores.
Basidiospores can also be dispersed passively through environmental vectors such as wind, water, or animals. Wind dispersal is the most common method of passive dispersal, where the shape of the stipe and cap of the fungi are adapted for optimal spore dispersal. For example, taller stipes and smaller basidiospores allow the spores to travel farther. Some fungi create their own draft by evaporating water, causing differences in air temperature beneath the hymenium to overcome still air.
Basidiospores are typically 5-10 microns long, but agaric basidiospores can be as small as 2 microns. They usually have an asymmetric shape due to their development on the basidium. The surface of the spore can be smooth or ornamented, and the spore wall consists of several layers, including the endosporium, episporium, and ectosporium. The ectosporium becomes sticky and slimy in mature spores.
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Basidiospores are supported by short pointed stalks called sterigmata
Basidiospores are reproductive spores produced by basidiomycete fungi, which include mushrooms, shelf fungi, rusts, and smuts. Basidiospores are supported by short, pointed stalks called sterigmata. Each basidiospore grows from the tip of a sterigma that projects from the basidium.
Sterigmata are narrow prongs or horns that usually bear four sexual spores called basidiospores. The number of basidiospores can vary from two to eight. Basidiospores are the result of karyogamy and meiosis in the sexual reproductive process. They are typically single-celled and range from spherical to oval to oblong to ellipsoid or cylindrical.
Basidiospores are produced by basidia, which are club-shaped structures that develop on the fertile hymenial tissues of mushrooms. Basidia are the fruiting bodies of mushroom-producing fungi, and they form four basidiocarps. The basidia of many mushrooms produce four sterigmata and four spores. However, some jelly fungi can produce eight or more spores per basidium, while yeasts produce a single sterigma and spore.
Basidiospores are forcibly ejected from the basidium and serve as the main air dispersal units for the fungi. They can be dispersed actively through a fungus's own mechanisms or passively through reliance on another organism or abiotic factor. Actively dispersed basidiospores are called ballistospores. They are discharged through a process involving the condensation of water near the base of the spore, known as Buller's drop. This shift in the centre of gravity causes the spore to break off of the sterigma.
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Basidia are borne on fruiting bodies called basidiocarps
Basidia are microscopic, spore-producing structures found on the basidiocarp (mushroom, fruiting body, basidioma) of basidiomycete fungi. They are club-shaped and usually bear four sexual spores called basidiospores, though this number can vary from two to eight. Basidiospores are produced on the fertile hymenial tissues of mushrooms, wrapping around the gills of agarics and the spines of hydnoid fungi, covering the surfaces of crust fungi, jelly fungi, and coral fungi, and lining the tubes of poroid fruiting bodies.
Basidiospores are usually forcibly ejected from the basidium, although they do not travel very far, clearing the sterigmata by only a few micrometers. They are then at the mercy of wind currents, and because of their small size and lightness, they may travel great distances before settling. The mechanism of basidiospore discharge is thought to involve minute changes in surface tension or electrostatic charges associated with a small drop on the sterigma just below the point of spore attachment.
Basidiospores are also produced by single cells of basidiomycete yeasts and by the germinating spores of rusts and smuts. Each basidiospore grows from the tip of a stalk or sterigma that projects from the basidium. The basidia of many mushrooms produce four sterigmata and four spores, although some jelly fungi can produce eight or more spores per basidium.
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Basidia are club-shaped
The basidium is typically club-shaped, being narrow at the stem and wide near its outer end. It is widest at the middle hemispherical dome at its apex, and its base is about half the size of the widest diameter at the highest point. Basidia with short and narrow bases are shaped like inverted eggs, while those with wide bases often resemble barrels. The basidiospores are borne on fruiting bodies (basidiocarps) and are usually conspicuous.
Basidia are often arranged in a single layer, or hymenium, and they support the basidiospores. The basidiospores are attached to the basidia by short, pointed stalks called sterigmata. Each basidium usually bears four sexual spores, although this number can vary between two and eight. The basidiospores are forcibly expelled at full growth, and the propulsive force is derived from a sudden change in the centre of gravity of the discharged spore.
Basidiomycetes, or club fungi, are named after the basidium, which is a club-shaped structure. The basidiospores are the result of karyogamy and meiosis in the sexual reproductive process. The lifecycle of a basidiomycete alternates between generation and a prolonged stage in which two nuclei (dikaryon) are present in the hyphae.
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Frequently asked questions
A basidium (plural: basidia) is a microscopic, club-shaped structure that produces spores in mushrooms.
Mushroom spores are called basidiospores.
Basidiospores are usually ejected forcibly from the basidium and are carried by wind currents.
Basidiospores are the sexual spores of mushrooms and are involved in their sexual reproduction.
Basidia are the structures that produce and bear the basidiospores, which are the reproductive spores.
