What is the life cycle of a gymnosperm?
The life cycle of gymnosperms is both haploid and diploid, i.e., they reproduce through the alternation of generations. They have a sporophyte-dominant cycle. The gametophyte phase is relatively short. The reproductive organs are usually cones. Male Cones – These have microsporophylls that contain microsporangia.
Do gymnosperms reproduce sexually or asexually?
Trees reproduce sexually through seeds (female) and pollen (male). Gymnosperms produce a naked seed whereas angiosperms (flowering plants) produce a true seed. Click to see full answer. People also ask, do gymnosperms reproduce with spores? In gymnosperms the cone is the female reproductive part and the pollen is the male reproductive part.
What are examples of gymnosperms?
Gymnosperms are quite essential, and their uses include:
- Most, especially the conifers, act as a source of wood. ...
- They act as a source of medicine. ...
- Some, such as pines, act as a turpentine source used in paints and polishes. ...
- They act as a source of food. ...
- They are used in making plastics and linoleum. ...
- Some are used as ornamentals, such as monkey puzzle plants.
- They act as a source of rosin, a type of resin. ...
What are the major characteristics of gymnosperms?
What are the major characteristics of gymnosperms?
- They do not have an outer covering or shell around their seeds.
- They do not produce flowers.
- They do not produce fruits.
- They are pollinated by the wind.
Does gymnosperm have spore?
Gymnosperms are sporophytes (a plant with two copies of its genetic material, capable of producing spores ). Their sporangia (receptacle in which sexual spores are formed) are found on sporophylls, plated scale-like structures that together make up cones.
Where are the spores on a gymnosperm?
Inside male cones, male spores develop into male gametophytes. Each male gametophyte consists of several cells enclosed within a grain of pollen. Inside female cones, female spores develop into female gametophytes. Each female gametophyte produces an egg inside an ovule.
Which types of spores are produced in gymnosperms?
Gymnosperms and angiosperms form two kinds of spores: microspores, which give rise to male gametophytes, and megaspores, which produce female gametophytes.
Do gymnosperms have seeds or spores?
Gymnosperms are a smaller, more ancient group, and it consists of plants that produce “naked seeds” (seeds that are not protected by a fruit). There are more than 1,000 species of gymnosperms still found on Earth.
Do cones release spores?
All conifers, including pines, are heterosporous and produce two kinds of spores, both on the same tree. The sites of spore production are the cones. The cones that most people recognize as 'pine cones' are female pine cones.
Is a gymnosperm a sporophyte?
Gymnosperms, like all vascular plants, have a sporophyte-dominant life cycle, which means they spend most of their life cycle with diploid cells, while the gametophyte (gamete-bearing phase) is relatively short-lived.
What are the types of spores?
There are various types of spores produced by various organisms. They include: sexual spores, asexual spores, exospores, endospores, vegetative spores, megaspores, and microspores.
What are examples of spores?
The definition of a spore is a small organism or a single cell being that is able to grow into a new organism with the right conditions. An example of a spore is a flower seed. Any small organism or cell that can develop into a new individual; seed, germ, etc. A megaspore or microspore.
Which type of spore are produced by Pteridophytes and gymnosperms?
In which plants motile ciliated spores are produced during spore formation ? The plants which bears only one kind of spores during Sporophytic, stage are known as ...........Q.Which type of spores are produce by pteridophytes and gymnosperms ?B.Somatic sporesC.HeterosporesD.HomosporesAnswer» c. Heterospores1 more row
Do angiosperms have spores?
In angiosperms, meiosis in the sporophyte generation produces two kinds of spores. which will develop into the female gametophyte generation.
What is present in gymnosperms?
As vascular plants, gymnosperms contain two conducting tissues, the xylem and phloem. The xylem conducts water and minerals from the roots to the rest of the plant and also provides structural support.
What does a gymnosperm seed consists of?
Gymnosperms. Seeds consist of an embryo already packaged within the seed, and nutritive tissue surrounded by a protective coat. 1. A seed contains a well-developed multicellular young plant with embryonic root, stem, and leaves already formed, whereas a plant spore is a single cell.
Do angiosperms have spores?
In angiosperms, meiosis in the sporophyte generation produces two kinds of spores. which will develop into the female gametophyte generation.
How are gymnosperm seeds dispersed?
Seed Dispersal in Gymnosperms In the typical gymnosperm cone, ripening and drying of cone and seed causes the cone scales to open and release the seeds. Dispersal is by wind, assisted by the presence of seed wings in some genera e.g. Pinus.
Where does meiosis occur in gymnosperm?
In Gymnosperms, it occurs in microsporangium and megasporangium to produce niicrospores (pollen grains) and megaspore. Similarly in angiosperms, meiosis occurs in microsporangium of anther and megasporangium of ovule.
Do conifers have spores?
Conifers are heterosporous, generating two different types of spores: male microspores and female megaspores. These spores develop on separate male and female sporophylls on separate male and female cones. In the male cones, microspores are produced from microsporocytes by meiosis.
What is the sporophyte of a gymnosperm?
In gymnosperms, the plant sporophyte is recognized as the bulk of the plant itself, including roots, leaves, stems, and cones. The cells of the plant sporophyte are diploid and contain two complete sets of chromosomes. The sporophyte is responsible for the production of haploid spores through the process of meiosis.
What is a gymnosperm?
Gymnosperms are flowerless plants that produce cones and seeds. The term gymnosperm literally means "naked seed," as gymnosperm seeds are not encased within an ovary. Rather, they sit exposed on the surface of leaf-like structures called bracts. Gymnosperms are vascular plants of the subkingdom Embyophyta and include conifers, cycads, ginkgoes, ...
What is the meaning of the term "gymnosperm"?
They belong to the subkingdom Embophyta . The term "gymnosperm" literally means "naked seed.". This is because the seeds produced by gymnosperms are not encased in an ovary. Instead, gymnosperm seeds sit exposed on the surface of leaf-like structures called bracts. The four main divisions of gymnosperms are Coniferophyta, Cycadophyta, Ginkgophyta, ...
What is the life cycle of a gymnosperm?
In the gymnosperm life cycle, plants alternate between a sexual phase and an asexual phase. This type of life cycle is known as alternation of generations. Gamete production occurs in the sexual phase or gametophyte generation of the cycle. Spores are produced in the asexual phase or sporophyte generation.
What are some examples of vascular plants?
Some of the most recognizable examples of these woody shrubs and trees include pines, spruces, firs, and ginkgoes. Gymnosperms are abundant in temperate forest and boreal forest biomes with species that can tolerate moist ...
Where is the gymnosperm found?
This image shows the gymnosperm Welwitschia mirabilis found only in the African desert of Namibia. Artush/iStock/Getty Images Plus
Which division contains the largest variety of species among gymnosperms?
The Coniferophyta division contains conifers, which have the greatest variety of species among gymnosperms. Most conifers are evergreen (retain their leaves throughout the year) and include some of the largest, tallest and oldest trees on the planet. Examples of conifers include pines, sequoias, firs, hemlock, and spruces.
When did gymnosperms first appear?
The earliest reliable record of gymnosperms dates their appearance to the Carboniferous period (359–299 million years ago). Gymnosperms were preceded by the progymnosperms (“first naked seed plants”).
When did gymnosperms dominate the landscape?
In the Mesozoic era (251–65.5 million years ago), gymnosperms dominated the landscape. Angiosperms took over by the middle of the Cretaceous period (145.5–65.5 million years ago) in the late Mesozoic era, and have since become the most abundant plant group in most terrestrial biomes. The two innovative structures of pollen ...
Why are gametophytes not free living?
Because the gametophytes mature within the spores, they are not free-living, as are the gametophytes of other seedless vascular plants. Heterosporous seedless plants are seen as the evolutionary forerunners of seed plants. Seeds and pollen—two adaptations to drought—distinguish seed plants from other (seedless) vascular plants.
What is the process of the gametophyte releasing sperm?
The male gametophyte releases sperm, which must swim—propelled by their flagella—to reach and fertilize the female gamete or egg.
How do pollen and seed help plants?
The two innovative structures of pollen and seed allowed seed plants to break their dependence on water for reproduction and development of the embryo, and to conquer dry land. The pollen grains carry the male gametes of the plant. The small haploid (1 n) cells are encased in a protective coat that prevents desiccation (drying out) and mechanical damage. Pollen can travel far from the sporophyte that bore it, spreading the plant’s genes and avoiding competition with other plants. The seed offers the embryo protection, nourishment and a mechanism to maintain dormancy for tens or even thousands of years, allowing it to survive in a harsh environment and ensuring germination when growth conditions are optimal. Seeds allow plants to disperse the next generation through both space and time. With such evolutionary advantages, seed plants have become the most successful and familiar group of plants.
How many ovules are in a pine cone?
Female cones, or ovulate cones, contain two ovules per scale. One megasporocyte undergoes meiosis in each ovule. Only a single surviving haploid cell will develop into a female multicellular gametophyte that encloses an egg. On fertilization, the zygote will give rise to the embryo, which is enclosed in a seed coat of tissue from the parent plant. Fertilization and seed development is a long process in pine trees—it may take up to two years after pollination. The seed that is formed contains three generations of tissues: the seed coat that originates from the parent plant tissue, the female gametophyte that will provide nutrients, and the embryo itself. Figure 1 illustrates the life cycle of a conifer.
How do microsporocytes form pollen?
In the male cones, or staminate cones, the microsporocytes give rise to microspores by meiosis. The microspores then develop into pollen grains. Each pollen grain contains two cells: one generative cell that will divide into two sperm, and a second cell that will become the pollen tube cell.
What is the life cycle of a gymnosperm?
Life Cycle of Gymnosperms. Gymnosperms are vascular plants that produce seeds in cones. Examples include conifers such as pine and spruce trees. The gymnosperm life cycle has a dominant sporophyte generation. Both gametophytes and the next generation’s new sporophytes develop on the sporophyte parent plant.
How do gametophytes develop?
Each male gametophyte consists of several cells enclosed within a grain of pollen. Inside female cones, female spores develop into female gametophytes. Each female gametophyte produces an egg inside an ovule. Pollination occurs when pollen is transferred from a male to female cone.
What happens if sperm travels from the pollen to an egg?
If sperm then travel from the pollen to an egg so fertilization can occur, a diploid zygote results. The zygote develops into an embryo within a seed, which forms from the ovule inside the female cone. If the seed germinates, it may grow into a mature sporophyte tree, which repeats the cycle. YouTube. Craig Savage.
Where does the gametophyte generation take place?
In gymnosperms, the gametophyte generation takes place in a cone , which forms on the mature sporophyte plant. Each male gametophyte is just a few cells inside a grain of pollen. Each female gametophyte produces an egg inside an ovule. Pollination must occur for fertilization to take place.
Do zygotes need to be pollinated?
Pollination must occur for fertilization to take place. Zygotes develop into embryos inside seeds, from which the next sporophyte generation grows.
Where did the name Gymnosperm come from?
The name gymnosperm is derived from the Greek word for naked seeds ( gymnospermos ). Both gymnosperms and angiosperms are grouped under the spermatophyte group of evolved plants. Both produce seeds for the purpose of propagation. But, what differentiates them is the seed types.
How many gymnosperms are there?
The evolution of gymnosperms can be traced back to the Paleozoic era, during which they were found abundantly. At present, there are approximately 700-900 living gymnosperm species. They are basically woody, large-sized and bear evergreen foliage. The leaves are reduced, of which many gymnosperms have needle-shaped leaves.
How do gymnosperms get pollinated?
The production of sperm cells and egg cells is followed by pollination process. Pollination of gymnosperms takes place by means of winds and natural agents. Over here, the pollen grains containing the sperm cells are carried to the female gametophyte of the ovulate cones by wind or insects.
What is the sporophyte phase?
Sporophyte: Spore-bearing Phase. The sporophyte phase represents the adult, photosynthetic, diploid gymnosperm plant that produces the male cones (or pollen cones) and the female cones (ovulate cones). The former is usually smaller than the latter one. They develop in the same plant (monoecious) or different plants (dioecious).
What is the life cycle of a gymnosperm?
Life Cycle of Gymnosperms. In the life cycle of gymnosperms, the dominant sporophyte phase alternates with the short gametophyte phase. The sporophyte plant produces spores, while the gametophyte bears gametes. Leaf through this article to get an insight about gymnosperm life cycle in detail.
What are the different types of gymnosperms?
Of these, the Coniferophyta represents the largest group. Similar to other evolved plants, alternation of generations are present in the life cycle of gymnosperms. Two different forms that alternate each other are the spore bearing plant (sporophyte) and gamete bearing structure (gametophyte). The former is the dominant one and lasts for a longer period than the gametophyte phase in the gymnosperm life cycle. For simple understanding, you can study the life cycle of spruce or pine.
How long does it take for a gymnosperm to fertilize?
Thus, the time period between pollination and fertilization in gymnosperms is quite long, about a year. This newly formed sporophyte is enclosed in a seed in the form of an embryo.
Do ferns have vascular systems?
ferns have a vascular system, which allow them to grow taller
Do gymnosperms need water to reproduce?
Gymnosperms produce pollen and do not require water to reproduce
Overview
Life cycle
Gymnosperms, like all vascular plants, have a sporophyte-dominant life cycle, which means they spend most of their life cycle with diploid cells, while the gametophyte (gamete-bearing phase) is relatively short-lived. Like all seed plants, they are heterosporous, having two spore types, microspores (male) and megaspores (female) that are typically produced in pollen cones or ovulate co…
Classification
A formal classification of the living gymnosperms is the "Acrogymnospermae", which form a monophyletic group within the spermatophytes. The wider "Gymnospermae" group includes extinct gymnosperms and is thought to be paraphyletic. The fossil record of gymnosperms includes many distinctive taxa that do not belong to the four modern groups, including seed-bearing trees that have a somewhat fern-like vegetative morphology (the so-called "seed ferns" or pteridosperms). …
Diversity and origin
Over 1000 living species of gymnosperm exist. It was previously widely accepted that the gymnosperms originated in the Late Carboniferous period, replacing the lycopsid rainforests of the tropical region, but more recent phylogenetic evidence indicates that they diverged from the ancestors of angiosperms during the Early Carboniferous. The radiation of gymnosperms du…
Uses
Gymnosperms have major economic uses. Pine, fir, spruce, and cedar are all examples of conifers that are used for lumber, paper production, and resin. Some other common uses for gymnosperms are soap, varnish, nail polish, food, gum, and perfumes.
Genetics
The first published sequenced genome for any gymnosperm was the genome of Picea abies in 2013.
General bibliography
• Cantino, Philip D.; Doyle, James A.; Graham, Sean W.; Judd, Walter S.; Olmstead, Richard G.; Soltis, Douglas E.; Soltis, Pamela S.; Donoghue, Michael J. (August 2007). "Towards a phylogenetic nomenclature of Tracheophyta". Taxon. 56 (3): 822–846. doi:10.2307/25065864. JSTOR 25065864.
External links
• Gymnosperm Database
• Gymnosperms on the Tree of Life
• Albert Seward (1911). "Gymnosperms" . Encyclopædia Britannica (11th ed.).