Briofitas

Clasificado en Biology

Escrito el en English con un tamaño de 7.84 KB

 

Bryophytes

The bryophytes are characteristic of moist terrestrial environments, although some show adaptations that allow the occupation of all kinds of environments, resisting both the immersion in fully aquatic, and dehydration when they serve as successors in primary colonization, for example, rocks naked or even halted in the polar regions. It presents, however always dependent on the water, at least for the displacement of anterozóide plagued by the egg cell. This division has no representative marine.

The plants are commonly used as ornamental plants, and the tangle of roots of ferns used as substrate for growing orchids. The trunk of Samambaiuçu is used to fern. Some ferns are used as anthelmintics. Traditionally used in oriental cuisine, some shoots of ferns are known to be carcinogenic action.


Bryophytes

This Division comprises terrestrial plants with morphology quite simple, popularly known as "moss" or "liver". They are eukaryotic organisms, multicellular, where only the reproductive organs are unicellular, positioning themselves in the Plantae, as all other groups of land plants.

NOTE: bryon (Greek)-moss, and phyton (Greek)-plan.

  • They have chlorophyll a and b;

  • Contain starch as a storage polysaccharide;

  • The cells have wall (composed of cellulose);

  • Presence of cuticle;

  • Lifecycle diplobionte heteromorphic, sporophyte partially or completely dependent on the gametophyte;

  • Playing the organic;

  • Esporófito not branched, with a single terminal sporangium;

  • Gametângio and sporangia surrounded by layer of sterile cells.

The bryophytes are characteristic of moist terrestrial environments, although some show adaptations that allow the occupation of all kinds of environments, resisting both the immersion in fully aquatic, and dehydration when they serve as successors in primary colonization, for example, rocks naked or even halted in the polar regions. It presents, however always dependent on the water, at least for the displacement of anterozóide plagued by the OSFER. These divisions have no marine representatives.

The bryophytes are diplobionte, showing heteromorphic alternation of generations between gametophyte branched, photosynthetic and independent sporophyte not branched and at least partially dependent on the gametophyte.

From meiosis occurred in special structures of the sporophyte that arise spores germinate to give rise to the gametophytes. The spores can lead directly to the plant that will produce the reproductive structures, usually erect or cause a first phase filamentous, with uniseriate filament, branched, with cross-walls oblique to the longitudinal axis (protonema), which will result in the standing part.

The gametophytes can be divided into rhizoids, and filídios caulídios. The simplest have no differentiation between Filídios and caulídio and are usually prostrate, and are called stalks, while those which distinguishes between these structures, usually erect, are called leafy.

At the height of the spore structures arise reproductive characteristics, called archegonia, which differentiates the female gamete (egg cell) and anterídios, which differentiate the male gametes (anterozóide).

In bryophytes the zygote germinates on the mother plant and the resulting sporophyte remains attached to her throughout her life, with partial or total dependence.

The sporophytes are never branched and has different degrees of complexity according to the group to which they belong can be divided into foot, seta and capsule. The foot presents itself immersed in the gametophyte tissue and is responsible for absorption of substances. Supported by the arrow is the terminal sporangia, called capsule, with a wrap of tissue outside the protection function, and the spores by meiosis different from the inner layers (tissue sportiveOgen). In some cases, when the capsule has dehiscence transverse, there is an operculum that stands to allow the passage of the spores. The capsule can be partially or completely covered by the calyptra which is formed by remnants of the archegonium tissue moved during the development of the sporophyte, and provides additional protection. The sporophyte, but always dependent on the gametophyte may, in certain classes of Bryophyta (Musci and Anthocerotae), perform photosynthesis, at least during early development.

The bryophytes may have three types of reproduction

1. Gametes: In the right conditions of humidity, anterozóide small biflagellate and are released by breaking the wall of the antheridium, while cells of the archegonium channel burst, releasing a fluid that drives anterozóide to the egg cell, then there fertilization ;

2. Spurl: The release of spores occurs through hygroscopic movements of the teeth peristomium. These movements are due to variation of humidity;

3. Material - 4 ways to play:

  • Fragmentation: development of fragments of the talus in another individual.

  • Gems (or runners): structures specially differentiated with definite form, which will lead to a new individual. The gems are produced within struct-shaped cup called conceptacles.

  • Apomixis: development of the sporophyte on gametophyte occurs without meiosis. Usually occurs from a fragment of the arrow which gives rise to a gametophyte regeneration. May result in the formation of polyploid organisms.

  • Apogamia: development of the gametophyte in sporophyte without fertilization. Can occur not only from the gametes, but also filídios or Breakage protonema.

In antiquity, the term "muscus" was used by Greek and Roman scholars comprising, besides the actual bryophytes, lichens and some algae, vascular plants and even invertebrates.

Although some Renaissance authors have studied genera of medical interest, Dillenius (1741) in his "Historia muscarum" was the first author to study these organisms with more comprehension. However, the work has misinterpreted the capsule (sporangium) and anther and the spores and pollen grains. As a result, Linnaeus (1753) in "Species Plantarum" ranks as bryophytes near flowering.

The correct interpretation of the structures found in these plants, not only referntes the sporophyte, but also to the cycle of life, function and anterídios arqugônios was given by Hedwig (1801), allowing the establishment of a more correct to classify it.

Currently bryophytes are separated by most authors in 3 classes, Hepaticae, and Musci Anthoceotae (eg Schofield, 1985). Other authors treat these three classes and divisions.

  • Class Hepaticae: liverworts (Greek)-liver.

It consists of about 300 genera and 10,000 species.

  • Class Anthocerotae: anthos (Greek)-flower.

It consists of only 300 genera and species.

  • Class Musci: muscus (Latin)-moss.

It consists of about 700 genera and 14,000 species.