gonozooids dioecious homosporous Vrksa spermatia embryophytes Pearlwort strobili microsporangia sporophytes moschatus rosid gametophyte Phymatopus unifacial gametes angiosperms dioicous bryophytes sporangia unisexual megaphylls stolons selvages hermaphrodites cleistogamous lycophytes isogamy apomixis pycnidia sundews Cephalotus sporophyte haploid Bennettitales asexually protocarnivorous syncarpous Snapdragons