The aura can be in the form of prismatic colors, flashes of light, and sometimes stars. They usually last about 20 minutes and then go away. If these flashes or lines of light occur without a headache, it is called an ophthalmic migraine, or a migraine without a headache.
In gymnosperms and flowering plants, the megaspore is produced inside the nucellus of the ovule. During megasporogenesis, a diploid precursor cell, the megasporocyte or megaspore mother cell, undergoes meiosis to produce initially four haploid cells (the megaspores).
Alternation of generations overview. the gametophyte produces haplod gametes by mitosis; two gametes unite and form a diploid zygote; the zygote develops into a multicellular diploid sporophyte; the sporophyte produces haploid spores by meiosis; the spores develop into multicellular haploid gametophytes.porophyte. in organisms (plants and some algae) that have alternation of gnerations, the multicellular diploid form that results from the union of gamtes; it produces haploid spores by meiosis that develop into gametophytes.