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However, in ferns and their allies there are groups with undifferentiated spores but differentiated gametophytes. For example, the fern Ceratopteris thalictrioides has spores of only one kind, which vary continuously in size. Smaller spores tend to germinate into gametophytes which produce only sperm-producing antheridia.
A pteridophyte is a vascular plant (with xylem and phloem) that reproduces by means of spores.Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as "cryptogams", meaning that their means of reproduction is hidden.
Normal asexual reproduction of plants, such as propagation from cuttings or leaves, has never been considered to be apomixis. In contrast to parthenocarpy , which involves seedless fruit formation without fertilization, apomictic fruits have viable seeds containing a proper embryo, with asexual origin.
Asexual reproduction in plants occurs in two fundamental forms, vegetative reproduction and agamospermy. [1] Vegetative reproduction involves a vegetative piece of the original plant producing new individuals by budding, tillering , etc. and is distinguished from apomixis , which is a replacement of sexual reproduction, and in some cases ...
Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the full set of genes of their single parent and thus the newly created individual is genetically and ...
By asexual reproduction, an organism creates a genetically similar or identical copy of itself. The evolution of sexual reproduction is a major puzzle for biologists. The two-fold cost of sexual reproduction is that only 50% of organisms reproduce [ 1 ] and organisms only pass on 50% of their genes .
A type of asexual reproduction whereby viable seed s or spore s are produced asexually, without fertilization, such that the genetic material they contain is a clone of the parent's genetic material. A plant produced in this way is called an apomict. apomorphy
Lycopods reproduce asexually by spores. The plants have an underground sexual phase that produces gametes, and this alternates in the lifecycle with the spore-producing plant. The prothallium developed from the spore is a subterranean mass of tissue of considerable size, and bears both the male and female organs (antheridia and archegonia). [6]