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In biology, a spore is a unit of sexual (in fungi) or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. [1] Spores form part of the life cycles of many plants , algae , fungi and protozoa . [ 2 ]
Reproduction via spores involves the spreading of the spores by water or air. Algae and some fungi often use motile zoospores that can swim to new locations before developing into sessile organisms. Airborne spores are obvious in fungi, for example when they are released from puffballs. Other fungi have more active spore dispersal mechanisms.
The sporophyte produces spores (hence the name) by meiosis, a process also known as "reduction division" that reduces the number of chromosomes in each spore mother cell by half. The resulting meiospores develop into a gametophyte. Both the spores and the resulting gametophyte are haploid, meaning they only have one set of chromosomes.
There are around 64 spores in a leptosporangium. Scanning electron micrograph of fern leptosporangia. In a eusporangium, characteristic of all other vascular plants and some primitive ferns, the initials are in a layer (i.e., more than one). A eusporangium is larger (hence contain more spores), and its wall is multi-layered.
Spore types can be used as taxonomic characters in the classification within the Ascomycota. The most frequent types are the single-celled spores, which are designated amerospores. If the spore is divided into two by a cross-wall , it is called a didymospore.
The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi. [1] [2] Not all fungi form molds. Some fungi form mushrooms; others grow as single cells and are called microfungi (for example yeasts).
[10] [6] Differing sized spores have been observed in many fossilized plant species. [7] For example, the species Lepidophloios, also known as the scale tree, has been shown in fossils to have been heterosporous; [6] The scale tree had separate cones containing either male or female spores on the same plant. [6]
The spores are released during periods of high humidity and generally have a night-time or pre-dawn peak concentration in the atmosphere. [1] When basidiospores encounter a favorable substrate, they may germinate, typically by forming hyphae. These hyphae grow outward from the original spore, forming an expanding circle of mycelium.