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 Power of Movement in Plants to differing environments whilst at the same time answering some objections of his day that evolution could not account for changes in behavioural responses. In his conclusions, Darwin presents the key features of plants from an evolutionary perspective indicating that gradual modification of these processes in response to natural selective forces like light and water could enable extensive ability to adapt. The process that creates the circular or elliptical movement of the stem and tips of plants (circumnutation) was identified as a significant one in enabling plants to evolve and adapt to almost any environment on the planet. Darwin also