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Exosporic gametophytes can either be bisexual, capable of producing both sperm and eggs in the same thallus , or specialized into separate male and female organisms (dioicous). In heterosporous vascular plants (plants that produce both microspores and megaspores), the gametophytes develop endosporically (within the spore wall).
At least one of the spores develop into haploid female gametophytes, the megagametophytes. [1] The megaspore mother cell arises within the megasporangium tissue. In flowering plants the megasporangium is also called the nucellus, and the female gametophyte is sometimes called the embryo sac or embryonic sac.
Female gametophytes of the liverwort Marchantia polymorpha. Gametophores are prominent structures in seedless plants on which the reproductive organs are borne. [citation needed] [1] The word gametophore (more accurately gametangiophore) is composed of the greek ‘gamete-,’ referring (loosely) to gametangia [citation needed] and ‘-phore’ (Greek Φορά, "to be carried"). [2]
Megagametogenesis is the process of maturation of the female gametophyte, or megagametophyte, in plants. [1] During the process of megagametogenesis, the megaspore, which arises from megasporogenesis, develops into the embryonic sac, in which the female gamete is housed. [2] These megaspores then develop into the haploid female gametophytes. [2]
Close-up of a Schlumbergera flower, showing part of the gynoecium (specifically the stigma and part of the style) and the stamens that surround it. Plant reproductive morphology is the study of the physical form and structure (the morphology) of those parts of plants directly or indirectly concerned with sexual reproduction.
Typically haploid with dominant gametophyte stage. 8 autosomes and 1 allosome (sex chromosome). The sex-determination system used by this species and most other bryophytes is called UV. Spores can carry either the U chromosome, which results in female gametophytes, or the V chromosome, which results in males.
Location of ovules inside a Helleborus foetidus flower. In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the integument, forming its outer layer, the nucellus (or remnant of the megasporangium), and the female gametophyte (formed from a haploid megaspore) in its center.
Antheridia and archegonia occur on different gametophytes, which are then called dioicous. The moss Mnium hornum has the gametophyte as the dominant generation. It is dioicous: male plants produce only antheridia in terminal rosettes, female plants produce only archegonia in the form of stalked capsules. [26] Seed plant gametophytes are also ...