Alternation of generations ($n\leftrightarrow 2n$)

Alternation between a multicellular haploid gametophyte and a multicellular diploid sporophyte. meiosis produces spores, whereas fertilization restores the diploid condition; the generations grow by mitosis.

The generation developing from a zygote and producing spores through meiosis. In the usual land-plant cycle it is diploid. Its nutritional independence and stature differ markedly between bryophytes and vascular plants.

A structure in which spores are produced. One unbranched bryophyte sporophyte bears a single sporangium; branching sporophytes can distribute several sporangia on one body.

A microsporangium is a sporangium in which microspores are produced. In a heterosporous plant, those microspores develop into male gametophytes; production of sperm is a later step.

In a flowering plant, the anther contains microsporangia. Distinguishing the enclosing structure, the microspore and the mature pollen grain prevents several different developmental stages from being treated as synonyms.