|
The development of the gametophyte from the sporophyte without meiosis and spore production, so that the gametophyte has the same number of chromosomes as the sporophyte. If fertile gametes are formed by such a gametophyte then a sporophyte with twice the original number of chromosomes is produced. A polyploid series may be built up in this way. Apospory can be induced artificially in certain ferns, e.g. the lady fern (Athyrum filix-femina), by pinning segments of frond to damp sand. Prothalli then arise from buds on the frond.
Apospory may also be used to describe the condition in angiosperms in which a diploid embryo forms from a cell of the nucellus or chalaza and megaspore formation is bypassed (see adventive embryony). Compare apogamy.
|
