Sporangium
A sporangium is a spore-case or a receptacle for spores. Usually, this refers to sporangia (plural of sporangium) on a plant called sporangial. Most sporangial plants disperse their spores by using the wind. A few use water or animals.Spores are better suited to broadcasting because they require less energy and material for the plant to produce. Spores are also very resistant to drying and mechanical damage. The disadvatage is that spores have less resources than a seed, and can only germinate in nearly perfect conditions.
Sporangial plants tend to inhabit biomes with predictable microclimates and few animals to disperse seeds, such as tundra, or mountain-tops.
The predictable microclimate is necessary to assure good conditions, but it need not occur often, as long as it occurs more often than a plant's lifetime.
Categorized based on the developmental planes, there are eusporangium and leptosporangium. Leptosporangiate development involve a single initial cell that will become the stalk, wall, and spores of the sporangium. Only ferns of the order Filicales do this. There are around 64 spores in a leptosporangium. On the other hand, eusporangiate development happens to all other vascular plants. Eusporangium's initials are in a layer (i.e., more than one). An eusporangium are larger (hence contain much more spores), and its wall is multi-layer. Although the wall layer may be stretched and damaged, resulting only one cell-layer left.