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A sporangium (pl., sporangia) is a plant structure
producing and containing spores or gametes.
Sporangia occur on angiosperms, gymnosperms, ferns, fern allies, mosses, algae, and fungi.
Microsporangia are the structures on the stamens of flowers
called anthers, and the pollen-producing structures on the
microsporophylls of male conifer cones.
Megasporangia are the comparable "female" structures on these plants, associated with the flower carpel and the megasporangial cone. On ferns, the mature plant is a sporophyte that develops
sporangia—tiny, stalked sacs which contain meiospores—on all or just certain leaves (called sporophylls if sporangia are
present).
In mosses, the little case that rises above the vegetative growth on a thin stalk is called a
capsule or sporangium and, as in ferns, produces
meiospores. This sporophyte (diploid) growth arises out of the haploid archegonium after the ovum is
fertilized. The sporophyte initially has some chlorophyll, but later turns
brown and becomes dependent upon the gametophyte for nutrition, which is absorbed through the foot (base of the
stalk), embeded in the archegonial tissues.
Categorized based on developmental sequence, eusporangia and
leptosporangia are differentiated in the vascular plants. In a leptosporangium, found only in 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. In a eusporangium, characteristic of all other vascular plants, 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.
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