Sporangium


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sporangium

[spə′ran·jē·əm]
(botany)
A case in which asexual spores are formed and borne.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The sporophyte consists of a basal foot, setum or connective stalk supporting a single sporangium or capsule.
Sporangium wall pigmented with brown; megaspores with short ridges, wart-like projections (tuberculate to papillate) or almost smooth; plant terrestrial or amphibious in wet clay soils or on rock outcrops.
where o is the observed number of individuals showing the same directional change in reproductive condition (i.e., a change in sorus area or sporangium density for Macrocystis and Pterygophora, respectively), and e is the expected number of individuals showing the same directional change in reproductive condition under conditions of asynchrony.
1: Micrographs (300x magnification) of (A) sporangia of Phytophthora ramorum, (B) a zoospore exiting a sporangium of Phytophthora bilorbang, (C) chlamydospores of Phytophthora ramorum and (D) an oospore of Phytophthora alni subspecies uniformis.
In the tissues, the organism forms characteristic abundant, large thick walled sporangium like structures containing large number of endospores.
They are unique in that the partially dependent sporophyte has an intercalary meristem at the base of the sporangium (Fig.
were identified by their characteristic hyphae and sporangium. Saprolegnia sp.
Characteristic Bacillus pumilus Cell > 0.1 [micro]M - Spor shape-circular - Wollen sporangium - Anaerob growth + Voges proskauer - 8/6: PH Growth at nutrient broth pH + 7/5: PH wth at nutrient broth pH + Strach hydrolysis - Gelatin hyarolysis + Nitrate reduction - Growth at 40 c + Growth at 50 c + Utilization of: Citrate + D(+)Glucose + L-Arabinose + D-Xylose + D-Mannitol + Table 8: Used tests to identifing Pseudomonas fluorescens (Shaad et al., 2001).
sporangiospore: Any spore produced from a sporangium.
Those which microscopically have ellipsoidal or cylindrical pores that are centrally or terminally positioned in the sporangium were recognized as typical of Bacillus cereus.
Sporangiospores of Pilobolus are contained within sporangia, making the sporangium the repository of a sample of cells that can be a source of DNA or protein.
The features that are most useful for distinguishing among Mucorales are the presence of the rhizoids, the shape of sporangium, the length of sporangiophore, and the shape of columella, the presence or absence of apophysis and collarette, and the organization and branching of stolons (3-12).