structure of monomeric gametophyte of equisetum arvense horsetail with archegonium and antheridium

antheridium archegonium arvense background biology botany developing diagram drawing equisetum fertilisation fertilization flora gamete gametophyte germinating germination grass green horsetail illustration isolated monomeric morphology nature part parts phytomorphology plant puzzlegrass reproduction rhizoids rhizome scheme snake sperm structure vector white zygote