AY Honors/Lichens, Liverworts & Mosses/Answer Key/es

Líquenes, hepáticas y musgos
Asociación General Estudio de la naturaleza	Destreza: 3 Año de introducción: 1961

Requisitos

Conexión Logros para la Investidura: Esta especialidad está relacionada con los requisitos de Logros para la Investidura para ORIENTADOR Estudio de la naturaleza que requiere (como una de dos opciones) completar un proyecto que es igual al requisito #6 de esta especialidad.

1

Conocer el ciclo de vida de un musgo, un liquen o una hepática.

Life cycle of moss

Most kinds of plants have a double portion of chromosomes in their cells (diploid, i.e. each chromosome exists with a partner that contains the same genetic information) whilst mosses have only a single set of chromosomes (haploid, i.e. each chromosome exists in a unique copy within the cell). There are periods in the moss lifecycle when they do have a full, paired set of chromosomes but this is only during the sporophyte stage.

In some mosses, green vegetative structures called gemmae are produced on leaves or branches, which can break off and form new plants without the need to go through the cycle of fertilization. This is a means of asexual reproduction.

2

¿Qué son los líquenes?

Lichens are symbiotic associations of a fungus with a photosynthetic partner (called a photobiont) that can produce food for the lichen from sunlight. The photobiont is usually either green alga or cyanobacterium.

3

Nombrar por lo menos dos maneras de cómo los líquenes han sido de valor para el hombre.

Soil Stabilization

Most lichens grow on stable rock surfaces or the bark of old trees, but many others grow on soil and sand. In these latter cases, lichens are often an important part of soil stabilization; indeed, in some desert ecosystems, vascular (higher) plant seeds cannot become established except in places where lichen crusts stabilize the sand and help retain water.

4

¿Cómo se diferencian las hepáticas a todas las demás plantas verdes? Mencionar uno que se utiliza en acuarios. ¿Cuál es su función?

Liverworts have a unicellular, root-like structure called a rhizoid which anchors it to its substrate. Many other plants have rhizoids, but only in the liverwort is the rhizoid unicellular.

5

Describir al menos tres maneras importantes de cómo el musgo se ha desempeñado en la economía del hombre.

Agriculture

Peat (Sphagnum moss) is used to loosen and fertilize soil for agriculture. It is also used in the construction material Peatcrete, and it has been used as fuel.

Landscaping

Moss is used as a base layer in the art of bonsai. It is also a popular terrarium plant.

Medicine

Moss was used for dressing wounds during World War I. It was also used as pillow filler for soldiers to rest upon when they were transported from the battlefield to the hospital.

Wallpaper

Sphagnum moss was used as wallpaper in the early 1900's.

6

Hacer un jardín de musgo (pequeño terrario) o «jardín eterno» utilizando por lo menos tres diferentes clases de musgos y líquenes.

Note: This activity meets a requirement in the Ranger AY Nature Study curriculum.

A terrarium may be constructed from any clear container of nearly any size, from baby food jars to storage tubs.

Start by putting down a layer of gravel, rocks, vermiculite or Perlite. Then place a layer of soil on top of this. Place the plants atop the soil and add a few rocks for interest. Water once, but do not overwater. Put the lid on and place the container in a place where it can receive indirect sunlight. If algae begins to grow on the container walls, move to a more shady location. You should not need to open the lid for months, as the terrarium will develop its own climate, and all the moisture remains in the container.

7

Buscar e identificar cinco líquenes, una hepática y seis musgos.

There are thousands of species of lichens, liverworts, and mosses, and providing an identification guide is well beyond the scope of this chapter. In order to meet this requirement, you will most likely need to obtain a field guide. Here are a few possibilities:

8

Observar las cápsulas (esporangios) de diferentes clases de musgo bajo una lupa para ver las diferencias en los «topes del pelo» y «dientes» que separan a muchas especies.

Arthrodontous capsule of Dicranella varia

Capsule structure

Among the Bryopsida, the structure of the capsule (sporangium) and its pattern of development is very useful both for classifying and for identifying moss families. Most Bryopsida produce a capsule with a lid (the operculum) which falls off when the spores inside are mature and thus ready to be dispersed. The opening thus revealed is called the stoma (meaning "mouth") and is surrounded by one or two peristomes. A peristome is a ring of triangular "teeth" formed from the remnants of specially thickened cell walls. There are usually 16 such teeth in a single peristome, and in the Bryopsida the teeth are separate from each other and able to both fold in to cover the stoma as well as fold back to open the stoma. This articulation of the teeth is termed arthrodontous.

There are two basic arthrodontous peristome types. The first is termed haplolepidous and consists of a single circle of 16 peristome teeth. The second type is the diplolepidous peristome fround in subclass Bryidae. In this type, there are two rings of peristome teeth—an inner endostome (short for endoperistome) and an exostome. The endostome is a more delicate membrane, and its teeth are aligned between the teeth of the exostome. There are a few mosses in the Bryopsida that have no peristome in their capsules. These mosses still undergo the same cell division patterns in capsule development, but the teeth do not fully develop.

For more information, see

• http://scitec.uwichill.edu.bb/bcs/bl14apl/bryo2.htm
• http://worldofmosses.com/dtm/dtm04.html

References

• Wikipedia articles:
  • Moss
  • Lichen
  • Marchantiophyta (Liverwort)
• http://www2.mcdaniel.edu/Biology/botf99/bryophtes/bryeco.htm