BIOL 2P93 Lecture Notes - Lecture 15: Gymnosperm, Motility, Isoetaceae

• School: Brock University
• Department: Biological Sciences
• Course: BIOL 2P93
• Professor: Susan Jonsson- Ninniss

Document Summary

All vp are oogamous =large non-motile eggs + small sperm (swim to egg), have alternation of heteromorphic generations, w/ large dominant sporophyte (than gametophyte). Early vp produced one type of spore b/c of meiosis = homosporous. Extant vp has homospory in most ferns, horsetails + some lycophytes where spores produced bisexual gametophytes. Heterospory: makes two types of spores in two different kinds of sporangia, seen in some. Lycophytes, few ferns + in all seed plants (extant plants). Two types of spores = microspores (produced in microsporangia) + megaspores (megasporangia), differentiated by function, not on relative size. = male gametophytes (microgametophytes) + megaspores = female gametophytes (megagametophytes). Both types of unisexual gametophytes are smaller than gametophytes of homosporous vp. Heterosporous vp = gametophytes develop w/in spore wall (endosporic development), homosporous = develop outside (exosporic development). General life cycle of a vp: sporophyte larger + complex than gametophyte, free-living. All vp are oogamous (large non-motile eggs and small sperm.