Vegetative growth is enlargement of the individual plant, while vegetative reproduction is any process that results in new plant “individuals” without production of seeds or spores. The female gametophyte is contained within a structure called the archegonium. The male spore will develop into a mature gametophyte that contains structures to make male gametes. Species with male and female flowers borne on separate plants (e.g., C. papaya or Cannabis)are termed dioecious, or “two homes.” The ovary, which may contain one or multiple ovules, may be placed above other flower parts (referred to as superior); or it may be placed below the other flower parts (referred to as inferior). Scholars still disagree on whether the fertilized central cell is considered gametophyte tissue. Reproduction is primarily asexual or sexual. The exine contains sporopollenin, a complex waterproofing substance supplied by the tapetal cells. These gametophytes are dioicous, producing either sperm or eggs but not both. Gymnosperm reproduction differs from that of angiosperms in several ways. One of the megaspores divides to form the multicellular female gametophyte, while the others divide to form the rest of the structure. [24] Once double fertilization occurs, the egg cell becomes the zygote which is then considered sporophyte tissue. Differentiate among the ways in which plants reproduce. Cycadophyta have 3 celled pollen grains while Ginkgophyta have 4 celled pollen grains. Together, the calyx and corolla are known as the perianth. [10] This occurs because in some gymnosperm orders, the germ cell is nonmobile and a direct pathway is needed, however, in Cycadophyta and Ginkgophyta, the germ cell is mobile due to flagella being present and a direct tube cell path from the pollination site to the egg is not needed. Because the two gametophytes differ in form and function, they are termed heteromorphic, from hetero- "different" and morph "form". [19] Just like in gymnosperms, the tube cell in angiosperms obtains nutrients from the sporophytic tissue, and may branch out into the pistil tissue or grow directly towards the ovule. The megaspore mother cell divides by meiosis to produce four haploid megaspores. Cell division of the zygote results in a new diploid multicellular organism, the second stage in the life cycle known as the sporophyte. The microspores develop inside the microsporangium. If any of the four parts is missing, the flower is known as incomplete. In hornworts and thallose liverworts the gametophyte is the flattish sheet. The seed is covered by a seed coat, which is derived from the female sporophyte. In a plant’s male reproductive organs, development of pollen takes place in a structure known as the microsporangium. In conifers such as pines, the green leafy part of the plant is the sporophyte; the cones contain the male and female gametophytes. There are two types of incomplete flowers: staminate flowers contain only an androecium; and carpellate flowers have only a gynoecium. Once mature, this single celled gametophyte is 90% smaller than the female gametophytes in other gymnosperm orders. The lifecycle of angiosperms follows the alternation of generations. Examples are shown for female and male cones. If all four whorls are present, the flower is described as complete. [8][11] After fertilization is complete in all orders, the remaining male gametophyte tissue will deteriorate. Once an egg and sperm meet, either from the same gametophyte or from different gametophytes, a zygote is formed. [12] Similar to the male gametophyte, the female gametophyte normally is fully dependent on the surrounding sporophytic tissue for nutrients and the two organisms cannot be separated. Microsporangium: Shown is (a) a cross section of an anther at two developmental stages. Development of Female Gametophyte The whole process of female gametophyte development occurs in two different phases. This central cell later fuses with a sperm to form the triploid endosperm. Once fertilization is complete, the resulting diploid zygote develops into the embryo; the fertilized ovule forms the other tissues of the seed. Structures of the flower: The four main parts of the flower are the calyx, corolla, androecium, and gynoecium. The ovule wall will become part of the fruit. The reproductive organs are multicellular. Upon germination, the tube cell forms the pollen tube through which the generative cell migrates to enter the ovary. [6] Microspores produce microgametophytes which produce sperm. All vascular plants are sporophyte dominant, and a trend toward smaller and more sporophyte-dependent female gametophytes is evident as land plants evolved reproduction by seeds. Each pollen grain has two coverings: the exine (thicker, outer layer) and the intine. [12][15] In select Gnetophyta, the female gametophyte stays singled celled. In the female cone, megaspore mother cells are present in the megasporangium. The human reproductive system and the ability to reproduce make life possible. The key difference between sporophyte and gametophyte is that the sporophyte is a diploid structure that participates in asexual reproduction while the gametophyte is a haploid structure that participates in sexual reproduction of plants.. Plants reproduce via asexual reproduction as well as via sexual reproduction. Pollen grains are male gametophytes carried by wind, water, or a pollinator. Each microsporangium contains hundreds of microspore mother cells that will each give rise to four pollen grains. Carpellate flower are clustered in the immature ears. One of the two sperm cells released by the generative cell fuses with the egg, forming a diploid zygote that divides to form the embryo.

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