Gymnosperm Gymnosperm The gymnosperms , also known as Acrogymnospermae, are a group of seed-producing plants that includes conifers, cycads, "Ginkgo", and gnetophytes. The term "gymnosperm" comes from the Greek composite word "γυμνόσπερμος" (γυμνός gymnos, "naked" and σπέρμα sperma, "seed"), meaning "naked seeds". The name is based on the unenclosed condition of their seeds (called ovules in their unfertilized state). The non-encased condition of their seeds 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, which are often modified to form cones,
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