Gemma (botany)

Last updated
Pygmy sundew Drosera roseana with gemmae. DroseraRoseanaGemmae.jpg
Pygmy sundew Drosera roseana with gemmae.

A gemma (English plural gemmas, Latin plural gemmae) is a single cell, or a mass of cells, or a modified bud of tissue, that detaches from the parent and develops into a new individual. This type of asexual reproduction is referred to as fragmentation. It is a means of asexual propagation in plants. These structures are commonly found in fungi, algae, liverworts and mosses, but also in some flowering plants such as pygmy sundews and some species of butterworts. [1] [2] [ page needed ] Vascular plants have many other methods of asexual reproduction including bulbils and turions.

Contents

In mosses and liverworts

Liverworts Marchantia with round cups, and Lunularia with crescent cups, both containing gemmae. Gemmae dislodged by rain are visible at the bottom of the image. Thallose liverwort (Marchantia and Lunularia spp.) showing clonal plantlets in gemma cups.jpg
Liverworts Marchantia with round cups, and Lunularia with crescent cups, both containing gemmae. Gemmae dislodged by rain are visible at the bottom of the image.

The production of gemmae is a widespread means of asexual reproduction in both liverworts and mosses. In liverworts such as Marchantia , the flattened plant body or thallus is a haploid gametophyte with gemma cups scattered about its upper surface. The gemma cups are cup-like structures containing gemmae. The gemmae are small discs of haploid tissue, and they directly give rise to new gametophytes. They are dispersed from gemma cups by rainfall. [3] [ page needed ]

The gemmae are bilaterally symmetrical and are not differentiated into dorsal and ventral surfaces. The mature gemmae fall on the ground and if conditions are suitable their germination starts immediately. The surface of the gemma which comes in contact of the soil gives out many rhizoids. This surface eventually becomes the lower(ventral) surface of the thallus. Meanwhile, the apical cells present in the two lateral notches become active and form two thalli in opposites directions.

Endogenous gemmae are also produced in liverworts, these are ovoid or ellipsoidal shaped, 2 celled at leaf tips or margins. Examples such as Bazzania kokawana (Fossombroniaceae), Endogemma caespiticia and also Riccardia species. [4]

Related Research Articles

<span class="mw-page-title-main">Gametophyte</span> Haploid stage in the life cycle of plants and algae

A gametophyte is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the sexual phase in the life cycle of plants and algae. It develops sex organs that produce gametes, haploid sex cells that participate in fertilization to form a diploid zygote which has a double set of chromosomes. Cell division of the zygote results in a new diploid multicellular organism, the second stage in the life cycle known as the sporophyte. The sporophyte can produce haploid spores by meiosis that on germination produce a new generation of gametophytes.

<span class="mw-page-title-main">Spore</span> Unit of reproduction adapted for dispersal and survival in unfavorable conditions

In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, fungi and protozoa. They were thought to have appeared as early as the mid-late Ordovician period as an adaptation of early land plants.

A sporangium ; pl.: sporangia) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other groups form sporangia at some point in their life cycle. Sporangia can produce spores by mitosis, but in land plants and many fungi, sporangia produce genetically distinct haploid spores by meiosis.

<span class="mw-page-title-main">Alternation of generations</span> Reproductive cycle of plants and algae

Alternation of generations is the predominant type of life cycle in plants and algae. In plants both phases are multicellular: the haploid sexual phase – the gametophyte – alternates with a diploid asexual phase – the sporophyte.

<span class="mw-page-title-main">Bryophyte</span> Terrestrial plants that lack vascular tissue

Bryophytes are a group of land plants (embryophytes), sometimes treated as a taxonomic division, that contains three groups of non-vascular land plants: the liverworts, hornworts, and mosses. In the strict sense, the division Bryophyta consists of the mosses only. Bryophytes are characteristically limited in size and prefer moist habitats although some species can survive in drier environments. The bryophytes consist of about 20,000 plant species. Bryophytes produce enclosed reproductive structures, but they do not produce flowers or seeds. They reproduce sexually by spores and asexually by fragmentation or the production of gemmae.

<span class="mw-page-title-main">Biological life cycle</span> Series of stages of an organism

In biology, a biological life cycle is a series of stages of the life of an organism, that begins as a zygote, often in an egg, and concludes as an adult that reproduces, producing an offspring in the form of a new zygote which then itself goes through the same series of stages, the process repeating in a cyclic fashion.

<span class="mw-page-title-main">Marchantiophyta</span> Botanical division of non-vascular land plants

The Marchantiophyta are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information. The division name was derived from the genus name Marchantia, named by French botanist Jean Marchant after his father.

<span class="mw-page-title-main">Antheridium</span> Part of a plant producing and containing male gametes

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 the collective term for the stamens of flowering plants.

Fragmentation in multicellular or colonial organisms is a form of asexual reproduction or cloning, where an organism is split into fragments upon maturation and the split part becomes the new individual.

<i>Marchantia</i> Genus of plants in the liverwort family Marchantiaceae

Marchantia is a genus of liverworts in the family Marchantiaceae and the order Marchantiales. The genus was named by French botanist Jean Marchant after his father.

<i>Lunularia</i> Species of liverwort

Lunularia is a genus of liverworts whose only species is Lunularia cruciata, the crescent-cup liverwort. Lunularia is either the only genus in the order Lunulariales, or may be placed in the order Marchantiales. The name, from Latin luna, moon, refers to the moon-shaped gemma cups.

<i>Conocephalum</i> Genus of plants

Conocephalum is a genus of complex thalloid liverworts in the order Marchantiales and is the only extant genus in the family Conocephalaceae. Some species of Conocephalum are assigned to the Conocephalum conicum complex, which includes several cryptic species. Conocephalum species are large liverworts with distinct patterns on the upper thallus, giving the appearance of snakeskin. The species Conocephalum conicum is named for its cone-shaped reproductive structures, called archegoniophores. Common names include snakeskin liverwort, great scented liverwort and cat-tongue liverwort.

<span class="mw-page-title-main">Prothallus</span> Gametophyte stage in the fern life cycle

A prothallus, or prothallium, is usually the gametophyte stage in the life of a fern or other pteridophyte. Occasionally the term is also used to describe the young gametophyte of a liverwort or peat moss as well. In lichens it refers to the region of the thallus that is free of algae.

Plant reproduction is the production of new 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 either parent. Asexual 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.

Sporogenesis is the production of spores in biology. The term is also used to refer to the process of reproduction via spores. Reproductive spores were found to be formed in eukaryotic organisms, such as plants, algae and fungi, during their normal reproductive life cycle. Dormant spores are formed, for example by certain fungi and algae, primarily in response to unfavorable growing conditions. Most eukaryotic spores are haploid and form through cell division, though some types are diploid sor dikaryons and form through cell fusion.we can also say this type of reproduction as single pollination

<i>Marchantia polymorpha</i> Species of liverwort

Marchantia polymorpha is a species of large thalloid liverwort in the class Marchantiopsida. M. polymorpha is highly variable in appearance and contains several subspecies. This species is dioicous, having separate male and female plants. M. polymorpha has a wide distribution and is found worldwide. Common names include common liverwort or umbrella liverwort.

<i>Tetraphis pellucida</i> Species of moss

Tetraphis pellucida, the pellucid four-tooth moss, is one of two species of moss in the acrocarpous genus Tetraphis. Its name refers to its four large peristome teeth found on the sporophyte capsule.

<i>Pogonatum urnigerum</i> Species of moss

Pogonatum urnigerum is a species of moss in the family Polytrichaceae, commonly called urn haircap. The name comes from "urna" meaning "urn" and "gerere" meaning "to bear" which is believed to be a reference made towards the plant's wide-mouthed capsule. It can be found on gravelly banks or similar habitats and can be identified by the blue tinge to the overall green colour. The stem of this moss is wine red and it has rhizoids that keep the moss anchored to substrates. It is an acrocarpous moss that grows vertically with an archegonium borne at the top of each fertilized female gametophyte shoot which develops an erect sporophyte.

<i>Syntrichia latifolia</i> Species of moss

Syntrichia latifolia, formerly Tortula latifolia, and commonly known as water screw-moss, is a species of moss belonging to the family Pottiaceae. Syntrichia species differ from members of Tortula due to synapomorphic leaf qualities, such as different basal and distal cells, as well as different costal cross sections where Tortula has an abaxial epidermis and Syntrichia lacks one.

<i>Podomitrium phyllanthus</i> Species of liverwort

Podomitrium phyllanthus is a thalloid liverwort in the family Pallaviciniaceae. It is found in wet forests and rainforests of Australia, New Zealand and New Caledonia.

References

  1. "Pygmy Sundew Gemmae". Cascade Carnivores. 2011. Retrieved December 14, 2011.
  2. Hughes, Stanley John. On conidia of fungi, and gemmae of algae, bryophytes and pteridophytes. NRC Research Press.
  3. Smith, AJE (1989) The Liverworts of Britain and Ireland, Cambridge University Press, Cambridge.
  4. Kishan Gopal Ramawat, Jean-Michel Merillon and K. R. Shivanna (Editors) Reproductive Biology of Plants (2016) , p. 70, at Google Books