<P> The structure that contains the spores in fungal species . </P> <P> In mosses, liverworts and hornworts, an unbranched sporophyte produces a single sporangium, which may be quite complex morphologically . Most non-vascular plants, as well as many lycophytes and most ferns, are homosporous (only one kind of spore is produced). Some bryophytes, most lycophytes, and some ferns are heterosporous (two kinds of spores are produced). These plants produce microspores and megaspores, which give rise to gametophytes that are functionally male or female, respectively . In some cases, both kinds of spores are produced in the same sporangium, and may even develop together as part of a spore tetrad . However, in most heterosporous plants there are two kinds of sporangia, termed microsporangia and megasporangia . A few ferns (Salviniaceae and Marsileaceae) and some lycophytes (the genera Selaginella and Isoetes and the extinct lepidodendrids) are heterosporous with two kinds of sporangia, as are all the seed plants . </P> <P> Sporangia can be terminal (on the tips) or lateral (placed along the side) of stems or associated with leaves . In ferns, sporangia are typically found on the abaxial surface (underside) of the leaf and are densely aggregated into clusters called sori . Sori may be covered by a structure called an indusium . Some ferns have their sporangia scattered along reduced leaf segments or along (or just in from) the margin of the leaf . </P> <P> Lycophytes, in contrast, bear their sporangia on the adaxial surface (the upper side) of leaves or laterally on stems . Leaves that bear sporangia are called sporophylls . If the plant is heterosporous, the sporangia - bearing leaves are distinguished as either microsporophylls or megasporophylls . In seed plants, sporangia are typically located within strobili or flowers . </P>

Where are the sporangia of a fern located