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Monoicy
Monoicy () is a sexual system in haploid plants (mainly bryophytes) where both sperm and eggs are produced on the same gametophyte, in contrast with dioicy, where each gametophyte produces only sperm or eggs but never both.Crandall-Stotler, B.J. & Bartholomew-Began, S.E. (2007). ''Morphology of Mosses (Phylum Bryophyta)''. In: Flora of North America Editorial Committee, eds. (1993+). ''Flora of North America North of Mexico''. 16+ vols. New York and Oxford. Volume 27, 2007.Bell, P.R. & Helmsley, A.R. (2000). ''Green plants, their origin and diversity'' (2nd ed.). Cambridge University Press. Both monoicous () and dioicous gametophytes produce gametes in gametangia by mitosis rather than meiosis, so that sperm and eggs are genetically identical with their parent gametophyte. It has been suggested that monoicy may have benefits in dry habitats where the ability to produce sporophytes is limited due to lack of water. Monoicy is similar to, and often conflated with, monoecy, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual System
A sexual system is a distribution of male and female functions across organisms in a species. The terms reproductive system and mating system have also been used as synonyms. Sexual systems play a key role in genetic variation and reproductive success, and may also have led to the origin or extinction of certain species. In flowering plants and animals, sexual reproduction involves meiosis, an adaptive process for repairing damage in the germline DNA transmitted to progeny. The distinctions between different sexual systems is not always clear due to phenotypic plasticity. Interest in sexual systems goes back to Charles Darwin, who found that barnacles include some species that are androdioecious and some that are dioecious. Types of sexual systems Flowering plants may have dimorphic or monomorphic sexual systems. In monomorphic sexual systems, a combination of hermaphrodite, male, and/or female flowers may be present on the same plant. Monomorphic sexual systems inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sporophyte
A sporophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the biological life cycle, life cycles of plants and algae. It is a diploid multicellular organism which produces asexual Spore, spores. This stage Alternation of generations, alternates with a multicellular haploid gametophyte phase. Life cycle The sporophyte develops from the zygote produced when a haploid egg cell is fertilized by a haploid sperm and each sporophyte cell therefore has a double set of chromosomes, one set from each parent. All Embryophyta, land plants, and most multicellular algae, have life cycles in which a multicellular diploid sporophyte phase alternates with a multicellular haploid gametophyte phase. In the Spermatophyte, seed plants, the largest groups of which are the gymnosperms (bare seeds) and angiosperms (fruiting plants), the sporophyte phase is more prominent than the gametophyte, and is the familiar green plant with its roots, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Reproduction
Plants may reproduce sexually or asexually. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from either parent. Vegetative reproduction produces new individuals without the fusion of gametes, resulting in clonal plants that are genetically identical to the parent plant and each other, unless mutations occur. In asexual reproduction, only one parent is involved. Asexual reproduction Asexual reproduction does not involve the production and fusion of male and female gametes. Asexual reproduction may occur through budding, fragmentation, spore formation, regeneration and vegetative propagation. Asexual reproduction is a type of reproduction where the offspring comes from one parent only, thus inheriting the characteristics of the parent. Asexual reproduction in plants occurs in two fundamental forms, vegetative reproduction and agamospermy. Vegetative reproduction involves a vegetative piece of the original pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Morphology
Phytomorphology is the study of the physical form and external structure of plants.Raven, P. H., R. F. Evert, & S. E. Eichhorn. ''Biology of Plants'', 7th ed., page 9. (New York: W. H. Freeman, 2005). . This is usually considered distinct from plant anatomy, which is the study of the internal structure of plants, especially at the microscopic level. Plant morphology is useful in the visual identification of plants. Recent studies in molecular biology started to investigate the molecular processes involved in determining the conservation and diversification of plant morphologies. In these studies transcriptome conservation patterns were found to mark crucial ontogenetic transitions during the plant life cycle which may result in evolutionary constraints limiting diversification. Scope Plant morphology "represents a study of the development, form, and structure of plants, and, by implication, an attempt to interpret these on the basis of similarity of plan and origin". There ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermaphrodite
A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many taxonomic groups of animals, primarily invertebrates, are hermaphrodites, capable of producing viable gametes of both sexes. In the great majority of tunicates, mollusks, and earthworms, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which either partner can act as the female or male. Hermaphroditism is also found in some fish species, but is rare in other vertebrate groups. Most hermaphroditic species exhibit some degree of self-fertilization. The distribution of self-fertilization rates among animals is similar to that of plants, suggesting that similar pressures are operating to direct the evolution of selfing in animals and plants. A rough estimate of the number of hermaphroditic animal species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epiphytism
An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phorophytes. Epiphytes take part in nutrient cycles and add to both the diversity and biomass of the ecosystem in which they occur, like any other organism. In some cases, a rainforest tree's epiphytes may total "several tonnes" (several long tons). They are an important source of food for many species. Typically, the older parts of a plant will have more epiphytes growing on them. Epiphytes differ from parasites in that they grow on other plants for physical support and do not necessarily affect the host negatively. An organism that grows on another organism that is not a plant may be called an epibiont. Epiphytes are usually found in the temperate zone (e.g., many mosses, liverworts, lichens, and algae) or in the trop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radula (plant)
''Radula'' is a genus of liverwort in the family Radulaceae. The genus includes 248 species of small plants that typically grow as green, scaly patches on tree trunks, logs, or rocks in moist environments. It is distinguished from other liverworts by several unique features, including the production of root-like structures (rhizoids) exclusively from leaf surfaces and characteristic branching patterns. The plants have rounded, overlapping leaves consisting of two unequal lobes, with considerable variation in structure across species. Following a major taxonomic revision in 2022, the genus comprises five subgenera with distributions ranging from tropical to temperate regions. The oldest known fossil species, ''R. cretacea'', found in Burmese amber, dates to the Cenomanian age, though molecular evidence suggests the genus originated in the Triassic period, around 228 million years ago. Taxonomy The genus ''Radula'' was historically subject to different taxonomic interpretatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conocephalum Conicum
''Conocephalum conicum'', also known as the great scented liverwort or snakeskin liverwort, is a liverwort species in the genus ''Conocephalum''. ''C. conicum'' is part of the ''Conocephalum conicum'' complex, which includes several cryptic species. The name ''C. conicum'' refers to the cone-shaped archegoniophore, which bear sporangia. Habitat and distribution ''C. conicum'' is one of the most common liverworts in northern hemisphere and is widely distributed throughout Canada. ''C. conicum'' is found in open woodlands, sandy banks, wet rocks or cliffs and moist soils and is strongly associated with calcareous substrates. Morphology Thalli ''C. conicum'' is the largest of the thalloid liverworts, growing up to 20 cm long. The thalli can grow to 17 mm wide. The thalli are very strong-smelling, with purplish margins; a dark green, leathery surface; flat and smooth. There is a set of lines running along the thalli's surface. The air pores, which are found between t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zygosity
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same locus (genetics), loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal Sex-determination system#Chromosomal determination, sex-determination system. If both alleles of a diploid organism are the same, the organism is #Homozygous, homozygous at that locus. If they are different, the organism is #Heterozygous, heterozygous at that locus. If one allele is missing, it is #Hemizygous, hemizygous, and, if both alleles are missing, it is #Nullizygous, nullizygous. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genes
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and non-coding genes. During gene expression (the synthesis of Gene product, RNA or protein from a gene), DNA is first transcription (biology), copied into RNA. RNA can be non-coding RNA, directly functional or be the intermediate protein biosynthesis, template for the synthesis of a protein. The transmission of genes to an organism's offspring, is the basis of the inheritance of phenotypic traits from one generation to the next. These genes make up different DNA sequences, together called a genotype, that is specific to every given individual, within the gene pool of the population (biology), population of a given species. The genotype, along with environmental and developmental factors, ultimately determines the phenotype ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inbreeding
Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely genetic distance, related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and other consequences that may arise from expression of wikt:deleterious, deleterious dominance (genetics), recessive traits resulting from incestuous sexual relationships and consanguinity. Animals avoid inbreeding only rarely. Inbreeding results in homozygous, homozygosity which can increase the chances of offspring being affected by recessive phenotypic trait, traits. In extreme cases, this usually leads to at least temporarily decreased Fitness (biology), biological fitness of a population (called inbreeding depression), which is its ability to survive and reproduce. An individual who inherits such deleterious traits is colloquially referred to as ''inbred''. The avoidance of expression of such deleterious recessive allel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archegonia
An archegonium (: archegonia), from the Ancient Greek ''ἀρχή'' ("beginning") and ''γόνος'' ("offspring"), is a multicellular structure or organ of the gametophyte phase of certain plants, producing and containing the ovum or female gamete. The corresponding male organ is called the antheridium. The archegonium has a long neck canal or venter and a swollen base. Archegonia are typically located on the surface of the plant thallus, although in the hornworts they are embedded. __TOC__ Bryophytes In bryophytes and other cryptogams, sperm reach the archegonium by swimming in water films, whereas in Pinophyta and angiosperms, the pollen are delivered by wind or animal vectors and the sperm are delivered by means of a pollen tube. In the moss ''Physcomitrella patens'', archegonia are not embedded but are located on top of the leafy gametophore (s. Figure). The Polycomb protein FIE is expressed in the unfertilized egg cell (right) as the blue colour after GUS staining reveals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
