Evolutionary history of plants and radially symmetrical, is an integumented megasporangium surrounded by a cupule. The megasporangium bears an unopened distal extension protruding above the multilobed integument. It is suspected that the extension was involved in anemophilous pollination. "Runcaria" sheds new light on the sequence of character acquisition leading to the seed. "Runcaria" has all of the qualities of seed plants except for a solid seed coat and a system to guide the pollen to the ovule. The first spermatophytes (literally: "seed plants") – that is, the first plants to bear true seeds – are called pteridosperms: literally, "seed ferns", so called because their
The Different Forms of Flowers on Plants of the Same Species is thus a triple chance of the maximum of fertility...There is thus the clearest proof that these complex arrangements have the important end of securing both a more abundant and more vigorous offspring.” Observations and experiments still continue today to further the understanding of this phenomenon instigated by Darwin in this original and seminal work. The Different Forms of Flowers on Plants of the Same Species The Different Forms of Flowers on Plants of the Same Species is a book by Charles Darwin first published in 1877. It is the fifth of his six books devoted solely to the study