Sporangium

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Related to sporangia: microsporangia

sporangium

[spə′ran·jē·əm]
(botany)
A case in which asexual spores are formed and borne.

Sporangium

 

a plant organ in which spores are formed. A sporangium may be unicellular (in many lower plants) or multicellular (in higher plants). Certain unicellular green algae undergo complete transformation in the sporangium. In multicellular algae, such as Ulothrix and Ulva, cells indistinct from other cells may become sporangia; in Ectocarpus and Laminaría the sporangium is formed from cells that differ from all other cells and occupy a definite position on the thallus. In certain acellular plants sporangia are formed on the thallus by forming a septum. The sporangia of some oomycetes become conidia, fall off, and sprout. The names of sporangia in lower plants reflect the structural features of the spores that form in them (for example, zoo-sporangium), the number of spores (monosporangium, tetraspo-rangium), the external appearance of the sporangium (cysto-carp), or the method of spore formation (mitosporangium, meiosporangium). The succession of nuclear phases in plant cycles of development is associated with meiosporangia.

Higher plants form only meiosporangia. In bryophytes the sporangium is represented by the capsule of the sporogonium. The sporangia of ferns develop on sporophylls or in their axils. Sporangia may be solitary or in groups (sori) and may be free or con-cresced (synangia). Isosporous ferns form sporangia of a single type, which produce spores that germinate in bisexual prothallia. Heterosporous ferns produce sporangia of two types— microsporangia and megasporangia—which, in turn, form microspores and megaspores (from which male and female prothallia develop). All seed plants are heterosporous; the nucellus of their ovule is homologous to a megasporangium. The pollen cell in an-giosperms is homologous to a microsporangium.

REFERENCES

See references under .

A. N. SLADKOV

References in periodicals archive ?
proliferating sporangia (b) at maturity a unique apical orifice generates juvenile sporangia developed continually in chain arrangement (c) more than two successive sporangia borne in a chain/ (a) Scale bar =50[micro]m; (b) Scale bar =25[micro]m; (c) Scale bar =50[micro]m.
A contingency analysis was performed comparing isolation success of composts inoculated using zoospores and those inoculated using hyphal plugs bearing sporangia.
Differentiation from other organisms that produce sporangia with endospores, such as Coccidioides immitis/C.
In petri dish experiments, more than 90 percent of sporangia failed to germinate when exposed to piperideine or piperidine concentrations of 51.
Sporangial form and dimensions: Sporangia were produced by cutting 5-mm-diameter disks from the advancing margin of a colony grown on V8 agar and floating these disks on 10 ml of 1-5% sterile soil extract for 4-5 days at 24 [degrees]C under fluorescent light as in Mitchell et al.
Isolates of Pilobolus were collected from the dung of horses in Ohio and Indiana and cultivated in microcosms until sporangia were produced.
A new species of Sawdonia with notes on the origin of microphyUs and lateral sporangia.
From the UAE collection, we measured spores from four sporangia with the following average sizes and standard deviations: 52.
Spores are spherical and subglobose, and were observed in a compact catenula arrangement within the sac or sporangia (fungal propagules) (Figure 5).