A gamete is a haploid cell that fuses with another haploid cell during fertilization (conception) in organisms that sexually reproduce. In species that produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual that produces the larger type of gamete—called an ovum —and a male produces the smaller tadpole-like type—called a sperm. In short a gamete is an egg or a sperm. This is an example of anisogamy or heterogamy, the condition in which females and males produce gametes of different sizes. In contrast, isogamy is the state of gametes from both sexes being the same size and shape, and given arbitrary designators for mating type. The name gamete was introduced by the Austrian biologist Gregor Mendel. Gametes carry half the genetic information of an individual, one ploidy of each type, and are created through meiosis.
A sex organ is any part of an animal's body that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. The testis in the male, and the ovary in the female, are called the primary sex organs. The external sex organs – the genitals or genitalia, visible at birth in both sexes, and the internal sex organs are called the secondary sex organs.
Fertilisation or fertilization, also known as generative fertilisation, insemination, pollination, fecundation, syngamy and impregnation, is the fusion of gametes to initiate the development of a new individual organism or offspring. This cycle of fertilisation and development of new individuals is called sexual reproduction. During double fertilisation in angiosperms the haploid male gamete combines with two haploid polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation.
In botany, apomixis was defined by Hans Winkler as replacement of the normal sexual reproduction by asexual reproduction, without fertilization. Its etymology is Greek for "away from" + "mixing". This definition notably does not mention meiosis. Thus "normal asexual reproduction" of plants, such as propagation from cuttings or leaves, has never been considered to be apomixis, but replacement of the seed by a plantlet or replacement of the flower by bulbils were categorized as types of apomixis. Apomictically produced offspring are genetically identical to the parent plant.
The stamen is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium.
A somatic cell or vegetal cell is any biological cell forming the body of an organism; that is, in a multicellular organism, any cell other than a gamete, germ cell, gametocyte or undifferentiated stem cell.
A pollen tube is a tubular structure produced by the male gametophyte of seed plants when it germinates. It acts as a conduit to transport the male gamete cells from the pollen grain—either from the stigma to the ovules at the base of the pistil or directly through ovule tissue in some gymnosperms. In maize, this single cell can grow longer than 12 inches (30 cm) to traverse the length of the pistil.
Philodendron is a large genus of flowering plants in the Araceae family. As of September 2015, the World Checklist of Selected Plant Families accepted 489 species; other sources accept different numbers. Regardless of number of species, the genus is the second-largest member of the Araceae family. Taxonomically, the genus Philodendron is still poorly known, with many undescribed species. Many are grown as ornamental and indoor plants. The name derives from the Greek words philo- or "love, affection" and dendron or "tree". They are commonly called by their generic name.
An antheridium is a haploid structure or organ producing and containing male gametes. The plural form is antheridia, and a structure containing one or more antheridia is called an androecium. "Androecium" is also used as the collective term for the stamens of flowering plants.
Self-incompatibility (SI) is a general name for several genetic mechanisms in angiosperms, which prevent self-fertilization and thus encourage outcross and allogamy. It should not be confused with genetically controlled physical or temporal mechanisms that prevent self-pollination, such as heterostyly and sequential hermaphroditism (dichogamy).
A theca refers to a sheath or a covering.
Microsporangia are sporangia that produce microspores and give rise to male gametes. Microsporangia occur in all plants that have heterosporic life cycles, such as spike mosses. In gymnosperms and angiosperm anthers, the microsporangia produce the microsporocytes, the microspore mother cells, which then produce four microspores through the process of meiosis. In the microsporocyte of Arabidopsis thaliana, meiosis depends on the expression of genes that facilitate DNA repair and homologous recombination.
The microspores divide by mitosis to produce pollen grains.
Plant reproduction is the production of new individuals or offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from the parent or parents. Asexual reproduction produces new individuals without the fusion of gametes, genetically identical to the parent plants and each other, except when mutations occur. In seed plants, the offspring can be packaged in a protective seed, which is used as an agent of dispersal.
Cytoplasmic male sterility is total or partial male sterility in plants as the result of specific nuclear and mitochondrial interactions. Male sterility is the failure of plants to produce functional anthers, pollen, or male gametes.
Microgametogenesis is the process in plant reproduction where a microgametophyte develops in a pollen grain to the three-celled stage of its development. In flowering plants it occurs with a microspore mother cell inside the anther of the plant.
Oleosins are structural proteins found in vascular plant oil bodies and in plant cells. Oil bodies are not considered organelles because they have a single layer membrane and lack the pre-requisite double layer membrane in order to be considered an organelle. They are found in plant parts with high oil content that undergo extreme desiccation as part of their maturation process, and help stabilize the bodies.
Gynodioecy is a rare breeding system that is found in certain flowering plant species in which female and hermaphroditic plants coexist within a population. Gynodioecy is the evolutionary intermediate stage between hermaphroditism and dioecy. Gynodioecy is the opposite of androdioecy, which is a breeding system consisting of male and hermaphroditic plants in a population. Gynodioecy occurs as a result of a genetic mutation that inhibits a hermaphroditic plant from producing pollen, while keeping the female reproductive parts intact. Gynodioecy is extremely rare, with fewer than 1% of angiosperm species exhibiting the breeding system. Some notable species that exhibit a gynodioecious mating system include Beta vulgaris, Lobelia siphilitica, Silene, and Lamiaceae.
Xenia in plants is the effect of pollen on seeds and fruit of the fertilized plant. The effect is separate to the contribution of the pollen towards the next generation.
