Sporangium

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Related to sporangial: Sporangiospore

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

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A. N. SLADKOV

References in periodicals archive ?
The Zaluch Gorge Section is composed of 45-50% phytoclasts, 35-30% playnomorphs, 5-10% amorphous organic matter and 5-10% with rare occurrences of sporangial mass and leaf epidermal tissues.
Sporangial shapes ranged from ellipsoid, ovoid, pyriform, obpyriform, to spherical with a prominent papilla (C).
Leaves were inoculated with 20 L sporangial suspensions at the center 45 days after planting.
It is a relatively quick, easy, straightforward technique to disrupt sporangial cell walls with the release of DNA.
Zimmermann holds that the flower started with radial sporangial clusters, the sporophyll arising, following planation, from aggregations of mesomes.
Oospores can play a significant role in infection, and genes controlling resistance to sporangial inoculum can not be assumed to be the same as those that confer resistance to oosporic inoculum (Hash et al.
Sterile leaf blades pinnately dissected; veins free; fertile stalk with pinnately branched (grape-like) sporangial clusters Botrychium
Sporangial germination was recorded to be the lowest in the EtOAc fraction with value of 15.
These ferns have relatively large sporangia that develop from several sporangial initials and produce numerous spores at maturity (Eames, 1936).
After zoospore production (Ward and Stoessl, 1974), the zoospores were collected and filtered through Whatman no: 54 to remove sporangial cases and mycelial fragments.
The packaging of Anabaena filaments into sporocarps is facilitated by branched epidermal trichomes known as sporangial pair hairs.