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The importance of seedless vascular plants

Mosses and liverworts are often the first macroscopic organisms to colonize an area, both in a primary succession—where bare land is settled for the first time by living organisms—or in a secondary succession, where soil remains intact after a catastrophic event wipes out many existing species. Their spores are carried by the wind, birds, or insects. Once mosses and liverworts are established, they provide food and shelter for other species. In a hostile environment, like the tundra where the soil is frozen, bryophytes grow well because they do not have roots and can dry and rehydrate rapidly once water is again available. Mosses are at the base of the food chain in the tundra biome. Many species—from small insects to musk oxen and reindeer—depend on mosses for food. In turn, predators feed on the herbivores, which are the primary consumers. Some reports indicate that bryophytes make the soil more amenable to colonization by other plants. Because they establish symbiotic relationships with nitrogen-fixing cyanobacteria, mosses replenish the soil with nitrogen.

At the end of the nineteenth century, scientists observed that lichens and mosses were becoming increasingly rare in urban and suburban areas. Since bryophytes have neither a root system for absorption of water and nutrients, nor a cuticle layer that protects them from desiccation, pollutants in rainwater readily penetrate their tissues; they absorb moisture and nutrients through their entire exposed surfaces. Therefore, pollutants dissolved in rainwater penetrate plant tissues readily and have a larger impact on mosses than on other plants. The disappearance of mosses can be considered a bioindicator for the level of pollution in the environment.

Ferns contribute to the environment by promoting the weathering of rock, accelerating the formation of topsoil, and slowing down erosion by spreading rhizomes in the soil. The water ferns of the genus Azolla harbor nitrogen-fixing cyanobacteria and restore this important nutrient to aquatic habitats.

Seedless plants have historically played a role in human life through uses as tools, fuel, and medicine. Dried peat moss    , Sphagnum , is commonly used as fuel in some parts of Europe and is considered a renewable resource. Sphagnum bogs ( [link] ) are cultivated with cranberry and blueberry bushes. The ability of Sphagnum to hold moisture makes the moss a common soil conditioner. Florists use blocks of Sphagnum to maintain moisture for floral arrangements.

 The Sphagnum in the photo has the appearance of a bumpy red carpet with protruding black stalks.
Sphagnum acutifolium is dried peat moss and can be used as fuel. (credit: Ken Goulding)

The attractive fronds of ferns make them a favorite ornamental plant. Because they thrive in low light, they are well suited as house plants. More importantly, fiddleheads are a traditional spring food of Native Americans in the Pacific Northwest, and are popular as a side dish in French cuisine. The licorice fern, Polypodium glycyrrhiza, is part of the diet of the Pacific Northwest coastal tribes, owing in part to the sweetness of its rhizomes. It has a faint licorice taste and serves as a sweetener. The rhizome also figures in the pharmacopeia of Native Americans for its medicinal properties and is used as a remedy for sore throat.

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Go to this website to learn how to identify fern species based upon their fiddleheads.

By far the greatest impact of seedless vascular plants on human life, however, comes from their extinct progenitors. The tall club mosses, horsetails, and tree-like ferns that flourished in the swampy forests of the Carboniferous period gave rise to large deposits of coal throughout the world. Coal provided an abundant source of energy during the Industrial Revolution, which had tremendous consequences on human societies, including rapid technological progress and growth of large cities, as well as the degradation of the environment. Coal is still a prime source of energy and also a major contributor to global warming.

Section summary

Vascular systems consist of xylem tissue, which transports water and minerals, and phloem tissue, which transports sugars and proteins. With the development of the vascular system, there appeared leaves to act as large photosynthetic organs, and roots to access water from the ground. Small uncomplicated leaves are microphylls. Large leaves with vein patterns are megaphylls. Modified leaves that bear sporangia are sporophylls. Some sporophylls are arranged in cone structures called strobili.

The seedless vascular plants include club mosses, which are the most primitive; whisk ferns, which lost leaves and roots by reductive evolution; and horsetails and ferns. Ferns are the most advanced group of seedless vascular plants. They are distinguished by large leaves called fronds and small sporangia-containing structures called sori, which are found on the underside of the fronds.

Mosses play an essential role in the balance of the ecosystems; they are pioneering species that colonize bare or devastated environments and make it possible for a succession to occur. They contribute to the enrichment of the soil and provide shelter and nutrients for animals in hostile environments. Mosses and ferns can be used as fuels and serve culinary, medical, and decorative purposes.

Art connections

[link] Which of the following statements about the fern life cycle is false?

  1. Sporangia produce haploid spores.
  2. The sporophyte grows from a gametophyte.
  3. The sporophyte is diploid and the gametophyte is haploid.
  4. Sporangia form on the underside of the gametophyte.

[link] D.

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Questions & Answers

What are the events that occur in each phase of interphase
Hazey Reply
what is photosynthesis
Victor Reply
The process plants use to convert sunlight into food (energy).
Some other organisms use
types of photosynthesis
ps1 and ps2
what is used to determine phylogeny?
Israel Reply
which condition is the basis for a species to be reproductively isolated from other members?
Israel Reply
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8.Which statement about analogies is correct?
What is true about organisms that are a part of the same clade?
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(CH2O)n is the stoichiometric formula of
Marcellus Reply
what are nucleotide
Anastijjaninaiya Reply
Methane,ammonia,water and sugar are dissolved to form nuceotide
Introduction To Biology
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fred Reply
Branches of biology
no it does not occurs by bacterium
what is a brick?
Istifanus Reply
what is gene in biology?
yousaf Reply
it is a heredity unit
what is DNA
yousaf Reply
carrier of genetic information
deoxyribonucleic acid
it contains genetic information and brings it to one generation to other
it is of two Types circular DNA and linear DNA
plasmids are the type of small circular DNA which lies outside the genomic DNA
And what makes a virus to be difficult to destroy
what observation is made when dry seeds and soaked seeds are put in a vacuum flask
Robin Reply
there is respiration from the soak seeds which shows on the walls of the vacuum flask
what's mammals ?
Istifanus Reply
mammals are vertebrates ,any member group of vertebrates animals in which the young are nourished with milk from special mammary glands of the mother.
what are actin and myosin
Praveen Reply
they are muscle filaments
they make up the microfibrils of the muscle ,relaxing and contracting to cause movement
Please did anybody know the questions that will come out in the coming practical?
Why it is importantthat there are different types of protein in plasma membraine for the transport materials into and out of a cell?
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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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