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A case in which asexual spores are formed and borne.



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.


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References in periodicals archive ?
Additionally, total leaf length depended on K content, while the number of sporangia depended on P content (Fig.
Sporangia were mostly laterally attached and were about 40 x 30[micro]m.
Individual sporangia which adhered to the lids of the Petri dishes were collected using sterile inoculating needles and placed in 0.
Plants terrestrial, on rocks or epiphytic; rhizomes normally present, erect stems simple or branched; leaves appressed to ascending or spreading; sporangia in strobili.
Differences in pigmentation and variation in the extent of coverage of the velum over the sporangia inset into the inner base of the leaves (Fig.
lens and well-developed sporangia were selected, wiped clean to remove any diatom film, and stored in 1 [micro]m-filtered seawater under two layers of 70% shading cloth, two weeks prior to starting the conditioning of the experimental plates.
For this reason, the focus of this work was to develop a technique to use spores collected from the sporangia of Pilobolus growing on natural media as the source of cellular material.
ATHYRIUM {eh-THIR-ee-um} Roth 1799 * Lady Ferns * (Greek athyros, doorless; sporangia tardily pushing open margin of indusium.
Within these terrestrial forms the leaf base beyond the height of the sporangia is set deeply into the wet silt or peat.
One specimen of fern bearing sporangia with distinctive in situ spores has been identified as a new species of the epiphytic fern, Davallia (Conran et al.
Fructose supported the highest mycelia dry weight; while sporangia production was more in glucose.
Surrounding these sporangia was a mild to moderate, multifocal, lymphoplasmacellular inflammatory infiltrate (Figure 1, panel B).