Alternation of generations
Videos
Alternation of generations is the predominant type of life cycle in plants and algae. In plants, both phases are multicellular: the haploid sexual phase – the gametophyte – alternates with a diploid a
Gametophyte of the fern Onoclea sensibilis (flat thallus, bottom) with a descendant sporophyte beginning to grow from it (small frond, top)
Gametophyte of Mnium hornum, a moss
Sporophyte of Lomaria discolor, a fern
Gametophyte of Pellia epiphylla with sporophytes growing from the remains of archegonia
Spore
Videos
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of
Fresh snow partially covers rough-stalked feather-moss (Brachythecium rutabulum), growing on a thinned hybrid black poplar (Populus x canadensis). The last stage of the moss lifecycle is shown, where the sporophytes are visible before dispersion of their spores: the calyptra (1) is still attached to the capsule (3). The tops of the gametophytes (2) can be discerned as well. Inset shows the surrounding, black poplars growing on sandy loam on the bank of a
Sporangium of Fungi
Zygospores on Rhizopus
Aecia on foliage