Editing Sporangium

{{short description|Enclosure in which spores are formed}}
{{For |[[bacteria]]-related information|endospore}}
{{More citations needed |date=April 2018}}

A '''sporangium''' (from [[Late Latin]], {{etymology|grc|''{{Wikt-lang|grc|σπορά}}'' ({{grc-transl|σπορά}})|seed||''{{Wikt-lang|grc|ἀγγεῖον}}'' ({{grc-transl|ἀγγεῖον}})|vessel}}; {{plural form}}: '''sporangia''')<ref>{{Cite encyclopedia |url=https://lexico.com/definition/sporangium |archive-url=https://web.archive.org/web/20200528051444/https://www.lexico.com/definition/sporangium |url-status=dead |archive-date=May 28, 2020 |title=sporangium |dictionary=[[Lexico]] UK English Dictionary |publisher=[[Oxford University Press]]}}</ref> is an enclosure in which [[spore]]s are formed.<ref>{{cite book |last1=Rost |first1=Thomas L. |last2=Barbour |last3=Stocking |last4=Murphy |display-authors=1 |year=2006 |title=Plant Biology |edition=2nd |publisher=Thompson Brooks/Cole |isbn=9780495013938}}</ref> It can be composed of a [[unicellular organism|single cell]] or can be [[multicellular organism|multicellular]]. Virtually all [[plant]]s, [[fungus|fungi]], and many other groups form sporangia at some point in their [[biological life cycle|life cycle]]. Sporangia can produce spores by [[mitosis]], but in land plants and many fungi, sporangia produce genetically distinct [[haploid]] spores by [[meiosis]].

==Fungi==
[[File:Mature sporangium of a Mucor sp. fungus.jpg|alt=refer to caption|thumb|200px|[[Photomicrograph]] of a mature sporangium of an ''[[Absidia]]'' mold]]

In some phyla of fungi, the sporangium plays a role in [[asexual reproduction]], and may play an indirect role in [[sexual reproduction]]. The sporangium forms on the sporangiophore and contains [[Ploidy|haploid]] [[Cell nucleus|nuclei]] and [[cytoplasm]].<ref>{{cite web |title=Fungi |url=http://leavingbio.net/fungi/ |website=Leaving Certificate Biology |date=4 October 2018}}</ref> [[Spores]] are formed in the sporangiophore by encasing each haploid nucleus and cytoplasm in a tough outer [[membrane]]. During asexual reproduction, these spores are dispersed via wind and [[germination|germinate]] into haploid [[hypha]]e.<ref>{{cite web |title=Life History and Ecology of the Fungi |url=http://www.ucmp.berkeley.edu/fungi/fungilh.html |website=University of California Museum of Paleontology}}</ref> 

Although sexual reproduction in fungi varies between phyla, for some fungi the sporangium plays an indirect role in sexual reproduction. For [[Zygomycota]], sexual reproduction occurs when the haploid hyphae from two individuals join to form a [[zygosporangium]] in response to unfavorable conditions. The haploid nuclei within the zygosporangium then fuse into [[Ploidy|diploid]] nuclei.<ref>{{Cite book |last=Webster |first=John |url=https://www.worldcat.org/title/ocm74942051 |title=Introduction to Fungi |last2=Weber |first2=Roland |date=2007 |publisher=Cambridge University Press |isbn=978-0-521-80739-5 |edition=3 |location=Cambridge, UK ; New York |oclc=ocm74942051}}</ref> When conditions improve, the zygosporangium germinates, undergoes meiosis and produces a sporangium, which releases spores.

==Land plants==
[[File:XN Polytrichum spec.jpg|thumb|200px|alt=refer to caption|Moss sporangia (the capsule and the stalk/seta make up the [[diploid]] asexual [[sporophyte]] generation)<ref>{{cite web |title=Life Cycle of a Moss - Infographic |url=https://stemlounge.com/life-cycle-of-a-moss-infographic/ |publisher=STEM Lounge |date=2018-09-13 |language=en |access-date=2021-02-25}}</ref>]]

In [[moss]]es, [[liverwort]]s and [[hornwort]]s, an unbranched [[sporophyte]] produces a single sporangium, which may be quite complex morphologically. Most non-vascular plants, as well as many [[lycophytes]] and most ferns,{{clarify|reason=lycophytes and ferns are vascular plants, thus a part of this sentence must be wrong|date=April 2025}} are [[homosporous]] (only one kind of spore is produced). Some lycophytes, such as the [[Selaginellaceae]] and [[Isoetaceae]],<ref name=Stace>{{cite book |last=Stace |first=C. A. |author-link=Stace, C. A. |year=2019 |title=New Flora of the British Isles |edition=4th |publisher=C & M Logistics |location=Middlewood Green, Suffolk, U.K. |isbn=978-1-5272-2630-2}}</ref>{{rp|7}} the extinct [[Lepidodendrales]],<ref name=StewartandRothwell>{{cite book | last1=Stewart |first1=W.N. |last2=Rothwell |first2=G.W. |year= 1993 |title= Paleobotany and the Evolution of Plants | edition=2nd | location=Cambridge | publisher=[[Cambridge University Press]] | isbn=978-0-521-38294-6 }}</ref> and ferns, such as the [[Marsileaceae]] and [[Salviniaceae]] are [[heterosporous]] (two kinds of spores are produced).<ref name=Stace/>{{rp|18}}  These plants produce both [[microspores]] and [[megaspores]], which give rise to gametophytes that are functionally male or female, respectively.  Most heterosporous plants there are two kinds of sporangia, termed [[microsporangia]] and megasporangia.
[[File:Fern Sori.JPG|thumb|200px|alt=refer to caption|Sporangia (clustered in sori) on a [[fern]] leaf]]
[[File:Equisetum arvense sporangia.jpg|thumb|200px|alt=refer to caption|''[[Equisetum arvense]]'' [[strobilus]] cut open to reveal sporangia]]

Sporangia can be terminal (on the tips) or lateral (placed along the side) of stems or associated with leaves. In [[fern]]s, sporangia are typically found on the [[wikt:abaxial|abaxial]] surface (underside) of the leaf and are densely aggregated into clusters called [[Sorus|sori]]. Sori may be covered by a structure called an indusium. Some ferns have their sporangia scattered along reduced leaf segments or along (or just in from) the margin of the leaf. Lycophytes, in contrast, bear their sporangia on the [[wikt:adaxial|adaxial]] surface (the upper side) of leaves or laterally on stems. Leaves that bear sporangia are called [[sporophyll]]s. If the plant is heterosporous, the sporangia-bearing leaves are distinguished as either microsporophylls or megasporophylls. In seed plants, sporangia are typically located within [[strobili]] or flowers.

[[File:Fern sporangia in Saratoga CA.jpg|thumb|200px|alt=refer to caption|Clusters of sporangia on a fern]]

[[Cycad]]s form their microsporangia on microsporophylls which are aggregated into strobili. Megasporangia are formed into ovules, which are borne on megasporophylls, which are aggregated into strobili on separate plants (all cycads are dioecious). [[Conifer]]s typically bear their microsporangia on microsporophylls aggregated into papery pollen strobili, and the ovules, are located on modified stem axes forming compound ovuliferous cone scales. Flowering plants contain microsporangia in the anthers of [[stamen]]s (typically four microsporangia per anther) and megasporangia inside [[ovule]]s inside ovaries. In all seed plants, spores are produced by meiosis and develop into gametophytes while still inside the sporangium. The microspores become microgametophytes (pollen). The megaspores become megagametophytes (embryo sacs).{{citation needed|date=December 2024}}

===Eusporangia and leptosporangia===
Categorized based on developmental sequence, '''''eusporangia''''' and '''''leptosporangia''''' are differentiated in the vascular plants.
* In a leptosporangium, found only in leptosporangiate ferns, development involves a single initial cell that becomes the stalk, wall, and spores within the sporangium. There are around 64 spores in a leptosporangium.
[[File:Fern sporangia.jpg|thumb|200px|alt=refer to caption|[[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. Although the wall may be stretched and damaged, resulting in only one cell-layer remaining.

===Synangium===
A cluster of sporangia that have become fused in development is called a '''synangium''' (pl. '''synangia'''). This structure is most prominent in ''[[Psilotum]]'' and [[Marattiaceae]] such as ''[[Christensenia (plant)|Christensenia]]'', ''[[Danaea]]'' and ''[[Marattia]]''.

==Internal structures==
A [[Columella (botany)|columella]] (pl. columellae) is a sterile (non-reproductive) structure that extends into and supports the sporangium of some species. In fungi, the columella, which may be branched or unbranched, may be of fungal or host origin. ''[[Secotium]]'' species have a simple, unbranched columella, while in ''[[Gymnoglossum]]'' species, the columella is branched. In some ''[[Geastrum]]'' species, the columella appears as an extension of the stalk into the spore mass ([[gleba]]).<ref name=Kirk2008>{{cite book |vauthors=Kirk PM, Cannon PF, Minter DW, Stalpers JA |title=Dictionary of the Fungi. |url=https://archive.org/details/dictionaryfungit00kirk |url-access=limited |edition=10th |publisher=CABI |location=Wallingford |year=2008|page=[https://archive.org/details/dictionaryfungit00kirk/page/n171 161]|isbn=978-0-85199-826-8}}</ref>

==See also==
*[[Archegonium]]
*[[Antheridium]]
*[[Spore formation]]

==References==
{{Reflist}}

{{botany}}

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[[Category:Plant anatomy]]
[[Category:Fungal morphology and anatomy]]