Spore

Last updated October 08, 2024

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] They were thought to have appeared as early as the mid-late Ordovician period as an adaptation of early land plants.^[3]

Bacterial spores are not part of a sexual cycle, but are resistant structures used for survival under unfavourable conditions.^[4] Myxozoan spores release amoeboid infectious germs ("amoebulae") into their hosts for parasitic infection, but also reproduce within the hosts through the pairing of two nuclei within the plasmodium, which develops from the amoebula.^[5]

In plants, spores are usually haploid and unicellular and are produced by meiosis in the sporangium of a diploid sporophyte. In some rare cases, diploid spore is also produced in some algae, or fungi.^[6] Under favourable conditions, the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte, which eventually goes on to produce gametes. Two gametes fuse to form a zygote, which develops into a new sporophyte. This cycle is known as alternation of generations.

The spores of seed plants are produced internally, and the megaspores (formed within the ovules) and the microspores are involved in the formation of more complex structures that form the dispersal units, the seeds and pollen grains.

Definition

The term spore derives from the ancient Greek word σπορά spora, meaning "seed, sowing", related to σπόρος sporos, "sowing", and σπείρειν speirein, "to sow".

In common parlance, the difference between a "spore" and a "gamete" is that a spore will germinate and develop into a sporeling, while a gamete needs to combine with another gamete to form a zygote before developing further.

The main difference between spores and seeds as dispersal units is that spores are unicellular, the first cell of a gametophyte, while seeds contain within them a developing embryo (the multicellular sporophyte of the next generation), produced by the fusion of the male gamete of the pollen tube with the female gamete formed by the megagametophyte within the ovule. Spores germinate to give rise to haploid gametophytes, while seeds germinate to give rise to diploid sporophytes.

Classification of spore-producing organisms

Plants

Vascular plant spores are always haploid. Vascular plants are either homosporous (or isosporous) or heterosporous . Plants that are homosporous produce spores of the same size and type.

Heterosporous plants, such as seed plants, spikemosses, quillworts, and ferns of the order Salviniales produce spores of two different sizes: the larger spore (megaspore) in effect functioning as a "female" spore and the smaller (microspore) functioning as a "male". Such plants typically give rise to the two kind of spores from within separate sporangia, either a megasporangium that produces megaspores or a microsporangium that produces microspores. In flowering plants, these sporangia occur within the carpel and anthers, respectively.

Fungi

Fungi commonly produce spores during sexual and asexual reproduction. Spores are usually haploid and grow into mature haploid individuals through mitotic division of cells (Urediniospores and Teliospores among rusts are dikaryotic). Dikaryotic cells result from the fusion of two haploid gamete cells. Among sporogenic dikaryotic cells, karyogamy (the fusion of the two haploid nuclei) occurs to produce a diploid cell. Diploid cells undergo meiosis to produce haploid spores.^{[ citation needed ]}

Classification of spores

Spores can be classified in several ways such as by their spore producing structure, function, origin during life cycle, and mobility.

Below is a table listing the mode of classification, name, identifying characteristic, examples, and images of different spore species.

Mode of Classification	Name		Identifying Characteristic	Example Spore Containing Organism	Image
Spore Producing Structure	Sporangiospore		Produced by sporangium	Zygomycetes	Sporangium of Fungi
	Zygospores		Produced by zygosporangium	Zygomycetes	Zygospores on Rhizopus
	Ascospores		Produced by ascus	Ascomycetes	Ascospores of Didymella Rabiei
	Basidiospores		Produced by basidium	Basidiomycetes	Typical reproductive structure of a basidiomycete, including the basidiospore and basidium
	Aecispores		Produced by aecium	Rusts and Smuts	Aecia on foliage
	Urediniospores		Produced by uredinium	Rusts and Smuts	Uredinospores
	Teliospores		Produced by teilum	Rusts and Smuts	Microscopic image of teliospores
	Oospores		Produced by oogonium	Oomycetes	Oospores of Phytophthora agathidicida
	Carpospores		Produced by carposophorophyte	Red Algae	Light microscopy of Polysiphonia showing a carpospores and carposporophyte inside
	Tetraspores		Produced by tetrasphorophyte	Red Algae	Tetraspores of Polysiphonia
Function	Chalmydospore		Thick-walled resting spores of fungi produced to survive in unfavorable conditions	Asomycota	Pseudohyphae, chlamydospores and blastospores of Candida yeast.
	Parasitic Fungal Spore	Internal Spores	Germinate within a host		A parasitic pink fungi on a Lichen tree
	Parasitic Fungal Spore	External (Environmental) spores	Spores released by the host to infest other hosts ^[7]		A parasitic pink fungi on a Lichen tree
Origin During Life Cycle	Meiospores	Microspores	Produced sexually through meiosis, and give rise to a male gametophyte	Pollen in seed plants	In plants, microspores, and in some cases megaspores, are formed from all four products of meiosis.
	Meiospores	Megaspores (macrospores)	Produced sexually through meiosis, and give rise to a female gametophyte	Ovule in seed plants	In contrast, in many seed plants and heterosporous ferns, only a single product of meiosis will become a megaspore (macrospore), with the rest degenerating.
	Mitospores		Produced asexually though mitosis	Ascomycetes	Ascomycete containing mitospores
Mobility	Zoospores		Mobile through flagella	Some algae and fungi	Microscopic image of a Zoospore
	Aplanospores		Immobile, however still produce flagella
	Autospores		Immobile spores that do not produce flagella		Autospores of a strain of Jenufa aeroterrestrica
	Ballistospores		Forcibly discharged from the fungal fruiting body due to internal force (such as built up pressure)	Basidiospores and/or part of the genus Pilobus	Ballistospore mechanism of dispersal from fungi
	Stratismospores		Forcibly discharged from the fungal fruting body due to external force (such as raindrops or passing animals)	Puffballs	Puff Balls containing Stratismospores

External anatomy

Under high magnification, spores often have complex patterns or ornamentation on their exterior surfaces. A specialized terminology has been developed to describe features of such patterns. Some markings represent apertures, places where the tough outer coat of the spore can be penetrated when germination occurs. Spores can be categorized based on the position and number of these markings and apertures. Alete spores show no lines. In monolete spores, there is a single narrow line (laesura) on the spore.^[8] Indicating the prior contact of two spores that eventually separated.^[3] In trilete spores, each spore shows three narrow lines radiating from a center pole.^[8] This shows that four spores shared a common origin and were initially in contact with each other forming a tetrahedron.^[3] A wider aperture in the shape of a groove may be termed a colpus.^[8] The number of colpi distinguishes major groups of plants. Eudicots have tricolpate spores (i.e. spores with three colpi).^[9]

Spore tetrads and trilete spores

Envelope-enclosed spore tetrads are taken as the earliest evidence of plant life on land,^[10] dating from the mid-Ordovician (early Llanvirn, ~ 470 million years ago), a period from which no macrofossils have yet been recovered.^[11] Individual trilete spores resembling those of modern cryptogamic plants first appeared in the fossil record at the end of the Ordovician period.^[12]

Dispersal

Spores being ejected by fungi.

In fungi, both asexual and sexual spores or sporangiospores of many fungal species are actively dispersed by forcible ejection from their reproductive structures. This ejection ensures exit of the spores from the reproductive structures as well as travelling through the air over long distances. Many fungi thereby possess specialized mechanical and physiological mechanisms as well as spore-surface structures, such as hydrophobins, for spore ejection. These mechanisms include, for example, forcible discharge of ascospores enabled by the structure of the ascus and accumulation of osmolytes in the fluids of the ascus that lead to explosive discharge of the ascospores into the air.^[13]

The forcible discharge of single spores termed ballistospores involves formation of a small drop of water (Buller's drop), which upon contact with the spore leads to its projectile release with an initial acceleration of more than 10,000 g.^[14] Other fungi rely on alternative mechanisms for spore release, such as external mechanical forces, exemplified by puffballs. Attracting insects, such as flies, to fruiting structures, by virtue of their having lively colours and a putrid odour, for dispersal of fungal spores is yet another strategy, most prominently used by the stinkhorns.

In Common Smoothcap moss ( Atrichum undulatum ), the vibration of sporophyte has been shown to be an important mechanism for spore release.^[15]

In the case of spore-shedding vascular plants such as ferns, wind distribution of very light spores provides great capacity for dispersal. Also, spores are less subject to animal predation than seeds because they contain almost no food reserve; however they are more subject to fungal and bacterial predation. Their chief advantage is that, of all forms of progeny, spores require the least energy and materials to produce.

In the spikemoss Selaginella lepidophylla , dispersal is achieved in part by an unusual type of diaspore, a tumbleweed.^[16]

Origin

Spores have been found in microfossils dating back to the mid-late Ordovician period.^[3] Two hypothesized initial functions of spores relate to whether they appeared before or after land plants. The heavily studied hypothesis is that spores were an adaptation of early land plant species, such as embryophytes, that allowed for plants to easily disperse while adapting to their non-aquatic environment.^[3]^[17] This is particularly supported by the observation of a thick spore wall in cryptospores. These spore walls would have protected potential offspring from novel weather elements.^[3] The second more recent hypothesis is that spores were an early predecessor of land plants and formed during errors in the meiosis of algae, a hypothesized early ancestor of land plants.^[18]

Whether spores arose before or after land plants, their contributions to topics in fields like paleontology and plant phylogenetics have been useful.^[18] The spores found in microfossils, also known as cryptospores, are well preserved due to the fixed material they are in as well as how abundant and widespread they were during their respective time periods. These microfossils are especially helpful when studying the early periods of earth as macrofossils such as plants are not common nor well preserved.^[3] Both cryptospores and modern spores have diverse morphology that indicate possible environmental conditions of earlier periods of Earth and evolutionary relationships of plant species.^[3]^[18]^[17]

Gallery

Spores of the moss Bartramia ithyphylla. (microscopic view, 400x)
Dehisced fern sporangia. (microscopic view, no spores are visible)
Spores and elaters from a horsetail. ( Equisetum , microscopic view)
Fossil plant spores ( Scylaspora ) from Silurian deposits of Sweden.
Fruit mold with spores and distinguishable cellular growth. (2000x)
Spore clusters, formed inside sporangia of the slime mold Reticularia olivacea , from pine forests of eastern Ukraine.
Internal surface of the peridium of the slime mold Tubifera dudkae with spores.

Related Research Articles

<span class="mw-page-title-main">Gametophyte</span> Haploid stage in the life cycle of plants and algae

A gametophyte is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the sexual phase in the life cycle of plants and algae. It develops sex organs that produce gametes, haploid sex cells that participate in fertilization to form a diploid zygote which has a double set of chromosomes. Cell division of the zygote results in a new diploid multicellular organism, the second stage in the life cycle known as the sporophyte. The sporophyte can produce haploid spores by meiosis that on germination produce a new generation of gametophytes.

A sporangium ; pl.: sporangia) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other groups form sporangia at some point in their life cycle. Sporangia can produce spores by mitosis, but in land plants and many fungi, sporangia produce genetically distinct haploid spores by meiosis.

Alternation of generations is the predominant type of life cycle in plants and algae. In plants both phases are multicellular: the haploid sexual phase – the gametophyte – alternates with a diploid asexual phase – the sporophyte.

<span class="mw-page-title-main">Bryophyte</span> Terrestrial plants that lack vascular tissue

Bryophytes are a group of land plants, sometimes treated as a taxonomic division, that contains three groups of non-vascular land plants (embryophytes): the liverworts, hornworts, and mosses. In the strict sense, the division Bryophyta consists of the mosses only. Bryophytes are characteristically limited in size and prefer moist habitats although some species can survive in drier environments. The bryophytes consist of about 20,000 plant species. Bryophytes produce enclosed reproductive structures, but they do not produce flowers or seeds. They reproduce sexually by spores and asexually by fragmentation or the production of gemmae. Though bryophytes were considered a paraphyletic group in recent years, almost all of the most recent phylogenetic evidence supports the monophyly of this group, as originally classified by Wilhelm Schimper in 1879. The term bryophyte comes from Ancient Greek βρύον (brúon) 'tree moss, liverwort' and φυτόν (phutón) 'plant'.

The embryophytes are a clade of plants, also known as Embryophyta or land plants. They are the most familiar group of photoautotrophs that make up the vegetation on Earth's dry lands and wetlands. Embryophytes have a common ancestor with green algae, having emerged within the Phragmoplastophyta clade of freshwater charophyte green algae as a sister taxon of Charophyceae, Coleochaetophyceae and Zygnematophyceae. Embryophytes consist of the bryophytes and the polysporangiophytes. Living embryophytes include hornworts, liverworts, mosses, lycophytes, ferns, gymnosperms and angiosperms. Embryophytes have diplobiontic life cycles.

In biology, a biological life cycle is a series of stages of the life of an organism, that begins as a zygote, often in an egg, and concludes as an adult that reproduces, producing an offspring in the form of a new zygote which then itself goes through the same series of stages, the process repeating in a cyclic fashion.

A sporophyte is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase.

<span class="mw-page-title-main">Ovule</span> Female plant reproductive structure

In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the integument, forming its outer layer, the nucellus, and the female gametophyte in its center. The female gametophyte — specifically termed a megagametophyte — is also called the embryo sac in angiosperms. The megagametophyte produces an egg cell for the purpose of fertilization. The ovule is a small structure present in the ovary. It is attached to the placenta by a stalk called a funicle. The funicle provides nourishment to the ovule. On the basis of the relative position of micropyle, body of the ovule, chalaza and funicle, there are six types of ovules.

Dioecy is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly or indirectly. Dioecious reproduction is biparental reproduction. Dioecy has costs, since only the female part of the population directly produces offspring. It is one method for excluding self-fertilization and promoting allogamy (outcrossing), and thus tends to reduce the expression of recessive deleterious mutations present in a population. Plants have several other methods of preventing self-fertilization including, for example, dichogamy, herkogamy, and self-incompatibility.

A microsporangium (pl. microsporangia) is a sporangium that produces microspores that give rise to male gametophytes when they germinate. Microsporangia occur in all vascular plants that have heterosporic life cycles, such as seed plants, spike mosses and the aquatic fern genus Azolla. In gymnosperms and angiosperm anthers, the microsporangia produce microsporocytes, the microspore mother cells, which then produce four microspores through the process of meiosis. Microsporocytes are produced in the microsporangia of gymnosperm cones and the anthers of angiosperms. They are diploid microspore mother-cells, which then produce four haploid microspores by meiosis. These become pollen grains, within which the microspores divide twice by mitosis to produce a very simple gametophyte.

Double fertilization or double fertilisation is a complex fertilization mechanism of angiosperms. This process involves the fusion of a female gametophyte or megagametophyte, also called the embryonic sac, with two male gametes (sperm). It begins when a pollen grain adheres to the stigmatic surface of the carpel, the female reproductive structure of angiosperm flowers. The pollen grain begins to germinate, forming a pollen tube that penetrates and extends down through the style toward the ovary as it follows chemical signals released by the egg. The tip of the pollen tube then enters the ovary by penetrating through the micropyle opening in the ovule, and releases two sperm into the embryonic sac (megagametophyte).

Microspores are land plant spores that develop into male gametophytes, whereas megaspores develop into female gametophytes. The male gametophyte gives rise to sperm cells, which are used for fertilization of an egg cell to form a zygote. Megaspores are structures that are part of the alternation of generations in many seedless vascular cryptogams, all gymnosperms and all angiosperms. Plants with heterosporous life cycles using microspores and megaspores arose independently in several plant groups during the Devonian period. Microspores are haploid, and are produced from diploid microsporocytes by meiosis.

A prothallus, or prothallium, is usually the gametophyte stage in the life of a fern or other pteridophyte. Occasionally the term is also used to describe the young gametophyte of a liverwort or peat moss as well. In lichens it refers to the region of the thallus that is free of algae.

Megaspores, also called macrospores, are a type of spore that is present in heterosporous plants. These plants have two spore types, megaspores and microspores. Generally speaking, the megaspore, or large spore, germinates into a female gametophyte, which produces egg cells. These are fertilized by sperm produced by the male gametophyte developing from the microspore. Heterosporous plants include seed plants, water ferns (Salviniales), spikemosses (Selaginellaceae) and quillworts (Isoetaceae).

Plant reproduction is the production of new offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from either parent. Asexual reproduction produces new individuals without the fusion of gametes, resulting in clonal plants that are genetically identical to the parent plant and each other, unless mutations occur.

Sporogenesis is the production of spores in biology. The term is also used to refer to the process of reproduction via spores. Reproductive spores were found to be formed in eukaryotic organisms, such as plants, algae and fungi, during their normal reproductive life cycle. Dormant spores are formed, for example by certain fungi and algae, primarily in response to unfavorable growing conditions. Most eukaryotic spores are haploid and form through cell division, though some types are diploid sor dikaryons and form through cell fusion.we can also say this type of reproduction as single pollination

A megaspore mother cell, or megasporocyte, is a diploid cell in plants in which meiosis will occur, resulting in the production of four haploid megaspores. At least one of the spores develop into haploid female gametophytes (megagametophytes). The megaspore mother cell arises within the megasporangium tissue.

Heterospory is the production of spores of two different sizes and sexes by the sporophytes of land plants. The smaller of these, the microspore, is male and the larger megaspore is female. Heterospory evolved during the Devonian period from isospory independently in several plant groups: the clubmosses, the ferns including the arborescent horsetails, and progymnosperms. This occurred as part of the process of evolution of the timing of sex differentiation. Four extant groups of plants are heterosporous; Selaginella, Isoetes, Salviniales and seed plants.

Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete with a single set of chromosomes combines with another gamete to produce a zygote that develops into an organism composed of cells with two sets of chromosomes (diploid). This is typical in animals, though the number of chromosome sets and how that number changes in sexual reproduction varies, especially among plants, fungi, and other eukaryotes.

Climacium dendroides, also known as tree climacium moss, belongs in the order Hypnales and family Climaciaceae, in class Bryopsida and subclass Bryidae. It is identified as a "tree moss" due to its distinctive morphological features, and has four species identified across the Northern Hemisphere. The species name "dendroides" describes the tree-like morphology of the plant, and its genus name came from the structure of the perforations of peristome teeth. This plant was identified by Weber and Mohr in 1804. They often have stems that are around 2-10 cm tall and growing in the form of patches, looking like small palm-trees. They have yellow-green branches at the tip of stems. The leaves are around 2.5-3 mm long, with rounder stem leaves and pointier branch leaves. Their sporophytes are only abundant in late winter and early spring, and appears as a red-brown shoot with long stalk and cylindrical capsules.

References

↑ Setlow, Peter; Johnson, Eric A. (30 April 2014), Doyle, Michael P.; Buchanan, Robert L. (eds.), "Spores and Their Significance", Food Microbiology, Washington, DC, USA: ASM Press, pp. 45–79, doi:10.1128/9781555818463.ch3, ISBN 978-1-68367-058-2 , retrieved 13 December 2023
↑ "Tree of Life Web Project". Archived from the original on 5 February 2018. Retrieved 5 February 2018.
1 2 3 4 5 6 7 8 Wellman, C. H.; Gray, J. (29 June 2000). "The microfossil record of early land plants". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 355 (1398): 717–731, discussion 731–732. doi:10.1098/rstb.2000.0612. ISSN 0962-8436. PMC 1692785 . PMID 10905606.
↑ Abel-Santos, Ernesto (2012). Bacterial spores: current research and applications. Norfolk: Caister academic press. ISBN 978-1-908230-00-3.
↑ Ivan Fiala (10 July 2008). "Myxozoa". Tree of Life Web Project. Archived from the original on 16 February 2015. Retrieved 14 January 2014. Myxospores consist of several cells, which are transformed to shell valves, nematocyst-like polar capsules with coiled extrudible polar filaments and amoeboid infective germs.
↑ "Diploid Spore - an overview | ScienceDirect Topics". www.sciencedirect.com. Archived from the original on 13 December 2023. Retrieved 13 December 2023.
↑ "Biology of Microsporidia". 26 June 2008. Archived from the original on 26 June 2008. Retrieved 24 March 2024.
1 2 3 Punt, W.; Hoen, P. P.; Blackmore, S.; Nilsson, S. & Le Thomas, A. (2007). "Glossary of pollen and spore terminology". Review of Palaeobotany and Palynology. 143 (1): 1–81. Bibcode:2007RPaPa.143....1P. doi:10.1016/j.revpalbo.2006.06.008.
↑ Judd, Walter S. & Olmstead, Richard G. (2004). "A survey of tricolpate (eudicot) phylogenetic relationships". American Journal of Botany. 91 (10): 1627–44. doi: 10.3732/ajb.91.10.1627 . PMID 21652313.
↑ Gray, J.; Chaloner, W. G.; Westoll, T. S. (1985). "The Microfossil Record of Early Land Plants: Advances in Understanding of Early Terrestrialization, 1970–1984". Philosophical Transactions of the Royal Society B . 309 (1138): 167–195. Bibcode:1985RSPTB.309..167G. doi: 10.1098/rstb.1985.0077 . JSTOR 2396358.
↑ Wellman CH, Gray J (2000). "The microfossil record of early land plants". Philosophical Transactions of the Royal Society B . 355 (1398): 717–732. doi:10.1098/rstb.2000.0612. PMC 1692785 . PMID 10905606.
↑ Steemans, P.; Herisse, A. L.; Melvin, J.; Miller, M. A.; Paris, F.; Verniers, J.; Wellman, C. H. (2009). "Origin and Radiation of the Earliest Vascular Land Plants" (PDF). Science. 324 (5925): 353. Bibcode:2009Sci...324..353S. doi:10.1126/science.1169659. hdl: 1854/LU-697223 . ISSN 0036-8075. PMID 19372423. S2CID 206518080. Archived (PDF) from the original on 22 September 2017. Retrieved 1 November 2017.
↑ Trail F. (2007). "Fungal cannons: explosive spore discharge in the Ascomycota". FEMS Microbiology Letters. 276 (1): 12–8. doi: 10.1111/j.1574-6968.2007.00900.x . PMID 17784861.
↑ Pringle A, Patek SN, Fischer M, Stolze J, Money NP (2005). "The captured launch of a ballistospore". Mycologia . 97 (4): 866–71. doi:10.3852/mycologia.97.4.866. PMID 16457355.
↑ Johansson, Lönnell, Sundberg and Hylander (2014) Release thresholds for moss spores: the importance of turbulence and sporophyte length. Journal of Ecology, n/a-n/a.
↑ "False Rose of Jericho – Selaginella lepidophyllaFalse Rose of Jericho – Selaginella lepidophylla". Plant- and Flower guide. February 2009. Archived from the original on 15 July 2011. Retrieved 1 February 2010.
1 2 Norem, W. L. (1958). "Keys for the Classification of Fossil Spores and Pollen". Journal of Paleontology. 32 (4): 666–676. ISSN 0022-3360. JSTOR 1300785.
1 2 3 Strother, Paul K.; Foster, Clinton (13 August 2021). "A fossil record of land plant origins from charophyte algae". Science. 373 (6556): 792–796. Bibcode:2021Sci...373..792S. doi:10.1126/science.abj2927. ISSN 0036-8075. PMID 34385396.

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[1] Setlow, Peter; Johnson, Eric A. (30 April 2014), Doyle, Michael P.; Buchanan, Robert L. (eds.), "Spores and Their Significance", Food Microbiology, Washington, DC, USA: ASM Press, pp. 45–79, doi:10.1128/9781555818463.ch3, ISBN 978-1-68367-058-2 , retrieved 13 December 2023

[2] "Tree of Life Web Project". Archived from the original on 5 February 2018. Retrieved 5 February 2018.

[Wellman-2000b-3] 1 2 3 4 5 6 7 8 Wellman, C. H.; Gray, J. (29 June 2000). "The microfossil record of early land plants". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 355 (1398): 717–731, discussion 731–732. doi:10.1098/rstb.2000.0612. ISSN 0962-8436. PMC 1692785 . PMID 10905606.

[4] Abel-Santos, Ernesto (2012). Bacterial spores: current research and applications. Norfolk: Caister academic press. ISBN 978-1-908230-00-3.

[5] Ivan Fiala (10 July 2008). "Myxozoa". Tree of Life Web Project. Archived from the original on 16 February 2015. Retrieved 14 January 2014. Myxospores consist of several cells, which are transformed to shell valves, nematocyst-like polar capsules with coiled extrudible polar filaments and amoeboid infective germs.

[6] "Diploid Spore - an overview | ScienceDirect Topics". www.sciencedirect.com. Archived from the original on 13 December 2023. Retrieved 13 December 2023.

[7] "Biology of Microsporidia". 26 June 2008. Archived from the original on 26 June 2008. Retrieved 24 March 2024.

[PuntHoenBlacNils07-8] 1 2 3 Punt, W.; Hoen, P. P.; Blackmore, S.; Nilsson, S. & Le Thomas, A. (2007). "Glossary of pollen and spore terminology". Review of Palaeobotany and Palynology. 143 (1): 1–81. Bibcode:2007RPaPa.143....1P. doi:10.1016/j.revpalbo.2006.06.008.

[JuddOlms04-9] Judd, Walter S. & Olmstead, Richard G. (2004). "A survey of tricolpate (eudicot) phylogenetic relationships". American Journal of Botany. 91 (10): 1627–44. doi: 10.3732/ajb.91.10.1627 . PMID 21652313.

[Gray1985-10] Gray, J.; Chaloner, W. G.; Westoll, T. S. (1985). "The Microfossil Record of Early Land Plants: Advances in Understanding of Early Terrestrialization, 1970–1984". Philosophical Transactions of the Royal Society B . 309 (1138): 167–195. Bibcode:1985RSPTB.309..167G. doi: 10.1098/rstb.1985.0077 . JSTOR 2396358.

[Wellman2000-11] Wellman CH, Gray J (2000). "The microfossil record of early land plants". Philosophical Transactions of the Royal Society B . 355 (1398): 717–732. doi:10.1098/rstb.2000.0612. PMC 1692785 . PMID 10905606.

[SteemansHerisse2009-12] Steemans, P.; Herisse, A. L.; Melvin, J.; Miller, M. A.; Paris, F.; Verniers, J.; Wellman, C. H. (2009). "Origin and Radiation of the Earliest Vascular Land Plants" (PDF). Science. 324 (5925): 353. Bibcode:2009Sci...324..353S. doi:10.1126/science.1169659. hdl: 1854/LU-697223 . ISSN 0036-8075. PMID 19372423. S2CID 206518080. Archived (PDF) from the original on 22 September 2017. Retrieved 1 November 2017.

[Trail-13] Trail F. (2007). "Fungal cannons: explosive spore discharge in the Ascomycota". FEMS Microbiology Letters. 276 (1): 12–8. doi: 10.1111/j.1574-6968.2007.00900.x . PMID 17784861.

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