The Non-vascular plants Or bryophytes are those that lack roots, true stems, leaf veins and tubular vessels, conductive of liquids of vascular plants.
These types of plants do not have vascular system, that is to say, they do not possess xylem nor phloem. Despite not having these tissues, they have other simpler structures for water transport.
Moss, a non-vascular plant
The plant kingdom includes two major divisions: vascular plants and non-vascular plants. The latter do not have a wide variety of specialized tissue types.
The leaves of the liver, for example, have no cuticle, stomata or internal air spaces, or xylem or phloem. This does not allow them to control the loss of water and is called polyhydroxy.
Non-vascular plants include only mosses (Phylum Bryophyta, 10000 species worldwide), hepatic (Phylum Hepatophyta, 6000 species) and hornworts (Phylum Anthocerophyta).
Therefore, it is one of the botanical groups whose research is often complicated to perform, hence the information that exists on each species is not as complete as it is with other types of plants.
These plants are generally small and inhabit in varied environments. They can be found in jungles, deserts, at sea level or even in high altitudes.
Most of these plants absorb water through the surface of their tissues, which is why they are located in humid places or under water because these environments facilitate the process of absorption.
Types of non-vascular plants
Mosses (Phylum Bryophyta)
They have very primitive vessels and form neither xylem nor phloem. They are anchored to the ground through the rhizoids. Instead of stem, they have something similar called cauloide and instead of leaves, has very similar sheets called filoides.
In highland habitats, mosses colonize easily in the sun or in the shade, rocky cracks. They are important to prevent erosion, retain water and accelerate soil formation. This facilitates the colonization of these sites by other plants.
Familiar moss plants are haploid individuals (gametophytes) that produce sperm and / or eggs in separate structures between the upper leaves of moss.
Rainwater or heavy dew is necessary to transport the sperm to the egg for sexual reproduction.
Fertilization of the egg by sperm results in a diploid zygote growing on a sporophyte that has a spore capsule on the upper part of which produces meiosis (spore formation).
The filament and the capsule of the diploid sporophyte remain attached to the haploid gametophyte. The spores are released from the capsule and germinate to form new haploid individuals.
Hepatic (Phylum Hepatophyta)
This type of non-vascular plants do not have anything like vessels, they do not even show distinguishable structures unlike mosses. They absorb water and nutrients throughout their surface.
They can measure from 0.05 to 20 cm in diameter. The liverworts are included in the Hepatophyta, a division that includes about 8500 different species growing around the world, in places such as the Arctic and the tropics. There are approximately 60 different families of hepatic plants.
Commonly it grows in humid places although some can grow in sandy and dry zones. They can grow in two ways: having a leaf-like shape or taloses, growing on large flat sheets. Its leaves can be confused with mosses.
Horn liver (Phylum Anthocerophyta)
Horn liver is a type of Bryophyte. Its name is due to its long sporaphytes that have horn form, in this structure the plant produces esporas. They can measure between 1.27 and 1.9 cm.
These plants grow in temperate and tropical regions of the world. They can be found in tree trunks, along riverbanks in rivers or in humid places.
Because they have similar anchoring structures to hairs, they can adhere to logs or to the ground.
Representative species of non-vascular plants
Among the liverworts, 4 to 10 species are recognized, although information on most is difficult to find, and is reduced to botanical encyclopedias, or to specialists who are knowledgeable about the subject.
In any case, it is known that the majority owes its name to the geographical location where they are present, among them are:
H. nobilis var hepatica
They are found from the northern Alps to Scandinavia.
H. nobilis var pirenaica
Origin of the Pyrenees.
H. nobilis var japonica
They can be obtained in Japan.
H. nobilis var. Pubescens
They are located in Japan.
H. transsilvanica
They are usually obtained in the Carpathians and Transylvania.
H. acutiloba
They are commonly seen in North America.
H. americana
Originally from North America.
H. polymorpha dealer
It forms dense lawns of stems that reach 10 cm in length. It usually grows in peat bogs or wet meadows, in general, grows in highly humid areas.
Lunularia cruciata
Its name, in Latin, refers to the moon-shaped cups. Commonly you get it in Europe, California and Australia.
In it you can get lunularic acid, a dihydrostilbenoid.
Riccia Fluitans
It can measure between 1 and 2 cm wide and 1 and 5 cm high. It is capable of forming a large sphere of vegetable. It is considered by many as a plague.
Polytrichum commune
It is a moss whose common lengths are 5 to 10 cm. It is found through temperate and boreal latitudes in the northern hemisphere and also in Mexico, some islands of the Pacific and Australia.
It usually grows in wet marshes and in flower streams.
Vesicularia dubyana
Also known as Java moss, it is a freshwater plant. It commonly lives in countries in South Asia, including the island of Java, to which it owes its name.
It is usually seen in freshwater aquariums.
References
1. Alters, S. (2000). Biology: Understanding Life. : Jones & Bartlett Learning.
2. Bradt, P., Pritchard, H. (1984). Biology of Nonvascular Plants. USA: Times / Mosby College Pub.
3. Crowson, R. (1970). Classification and Biology. USA: Transaction Publisher.
4. Hammerson, G. (2004). Connecticut Wildlife: Biodiversity, Natural History, and Conservation. USA: UPNE.
5. McMeans, J. (2010). Differentiated Lessons and Assessments: Science. USA: Teacher Created Resources.
6. Ramirez, M., Hernandez, M. (2015). General biology. Mexico: Grupo Patria Editorial Group
7. Tobin, A., Dusheck, J. (2005). Asking About Life. USA: Cengage Learning.