Chapter Immune System. Chapter Reproduction and Development. Chapter Behavior. Chapter Ecosystems. Chapter Population and Community Ecology. Chapter Biodiversity and Conservation. Chapter Speciation and Diversity. Chapter Natural Selection. Chapter Population Genetics. Chapter Evolutionary History. Chapter Plant Reproduction.
Chapter Plant Responses to the Environment. Full Table of Contents. This is a sample clip. Sign in or start your free trial. JoVE Core Biology. Previous Video Next Video. Next Video Embed Share. Plant life on Earth consists of nonvascular, seedless vascular, and seed plants. Please enter your institutional email to check if you have access to this content.
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If you need immediate assistance, please email us at subscriptions jove. Thank You. Please enjoy a free hour trial. In order to begin, please login. Please click here to activate your free hour trial. If you do not wish to begin your trial now, you can log back into JoVE at any time to begin. Save to playlist. The non-vascular plants include mosses, hornworts and liverworts, and some algae. They are generally small plants limited in size by poor transport methods for water, gases and other compounds.
They reproduce via spores rather than seeds and do not produce flowers, fruit or wood. Some non-vascular plants have developed specialized tissue for water transport and other substances.
However this tissue does not contain lignin and so it is not considered true vascular tissue such as that found in the angiosperms, gymnosperms, ferns, and lycophytes. The Bryophytes are a division of plants that includes all non-vascular, land plants. This includes the mosses, hornworts, and liverworts. The three groups share a number of adaptations but are all genetically very different. Mosses are a phylum of around 14, non-vascular plants.
They are small plants that produce spores for reproduction instead of seeds and are found almost everywhere on Earth in moist environments. Mosses are the most numerous of the non-vascular plant types. Classified in the plant division Bryophyta , mosses are small, dense plants that often resemble green carpets of vegetation. Mosses are found in a variety of land biomes including the arctic tundra and tropical forests. They thrive in moist areas and can grow on rocks, trees, sand dunes, concrete, and glaciers.
Mosses play an important ecological role by helping to prevent erosion, aiding in the nutrient cycle, and serving as a source of insulation. Mosses acquire nutrients from the water and soil around them through absorption. They also have multicellular hair-like filaments called rhizoids that keep them firmly planted to their growing surface.
Mosses are autotrophs and produce food by photosynthesis. Photosynthesis occurs in the green body of the plant called the thallus. Mosses also have stomata , which are important for gas exchange needed to acquire carbon dioxide for photosynthesis. The moss life cycle is characterized by the alternation of generation, which consists of a gametophyte phase and sporophyte phase. Mosses develop from the germination of haploid spores that are released from the plant sporophyte.
The moss sporophyte is composed of a long stalk or stem-like structure called a seta with a capsule at the tip. The capsule contains plant spores that are released into their surrounding environment when mature.
Spores are typically dispersed by wind. Should the spores settle in an area that has adequate moisture and light, they will germinate. The developing moss initially appears as thin masses of green hairs that eventually mature into the leaf-like plant body or gametophore. The gametophore represents the mature gametophyte as it produces male and female sex organs and gametes. The male sex organs produce sperm and are called antheridia , while the female sex organs produce eggs and are called archegonia.
Water is a 'must-have' for fertilization to occur. Sperm must swim to archegonia in order to fertilize the eggs. Fertilized eggs become diploid sporophytes, which develop and grow out of the archegonia.
Within the capsule of the sporophyte, haploid spores are produced by meiosis. Once mature, the capsules open releasing spores and the cycle repeats again. Mosses spend the majority of their time in the dominant gametophyte phase of the life cycle.
Mosses are also capable of asexual reproduction. When conditions become harsh or the environment is unstable, asexual reproduction allows mosses to propagate faster. Asexual reproduction is accomplished in mosses by fragmentation and gemmae development. In fragmentation, a piece of the plant body breaks off and eventually develops into another plant.
Reproduction through gemmae formation is another form of fragmentation. Gemmae are cells that are contained within cup-like discs cupules formed by plant tissue in the plant body. Gemmae are dispersed when raindrops splash into the cupules and wash gemmae away from the parent plant. Gemmae that settle in suitable areas for growth develop rhizoids and mature into new moss plants.
Liverworts are non-vascular plants that are classified in the division Marchantiophyta. Their name is derived from the lobe-like appearance of their green plant body thallus that looks like the lobes of a liver.
There are two main types of liverworts. Leafy liverworts closely resemble mosses with leaf-like structures that protrude upward from the plant base. Thallose liverworts appear as mats of green vegetation with flat, ribbon-like structures growing close to the ground. Liverwort species are less numerous than mosses but can be found in almost every land biome.
Though more commonly found in tropical habitats, some species live in aquatic environments, deserts , and tundra biomes. Liverworts populate areas with dim light and damp soil. Like all bryophytes, liverworts do not have vascular tissue and acquire nutrients and water by absorption and diffusion. Liverworts also have rhizoids hair-like filaments that function similarly to roots in that they hold the plant in place.
Liverworts are autotrophs that require light to make food by photosynthesis. Unlike mosses and hornworts, liverworts do not possess stomata that open and close to obtain carbon dioxide needed for photosynthesis.
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