Fertilisation the Greek composite word γυμνόσπερμος (γυμνός gymnos, "naked" and σπέρμα sperma, "seed"), meaning "naked seeds", after the unenclosed condition of their seeds (called ovules in their unfertilised state). Their naked condition stands in contrast to the seeds and ovules of flowering plants (angiosperms), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, often modified to form cones, or at the end of short stalks as in Ginkgo. After being fertilised, the ovary starts to swell and develop into the fruit. With multi-seeded fruits, multiple grains of pollen are necessary for syngamy with
Evolutionary history of plants is not a viable food source for fungi, herbivores or detritovores, so is prone to preservation. It is also robust, so can withstand pressure and display exquisite, sometimes sub-cellular, detail. All multicellular plants have a life cycle comprising two generations or phases. The gametophyte phase has a single set of chromosomes (denoted 1"n), and produces gametes (sperm and eggs). The sporophyte phase has paired chromosomes (denoted 2"n), and produces spores. The gametophyte and sporophyte phases may be homomorphic, appearing identical in some algae, such as "Ulva lactuca", but are very different in all modern land plants, a condition known as