Number of species in the collection: 144.

Back to Kingdom: Plantae

 

 

Classes:                                            

 

Andreaeopsida (Group of Andreaea and relatives, a small arctic-alpine group)

Bryopsida (Typical mosses)

Polytrichopsida (Small group of typically hard mosses)

Sphagnopsida (Bog mosses, peat mosses)

 

Pictures of Bryophyta:                                

 

 

Characteristics of Bryophyta:                   

 

Mosses are a large group of plants with around 12,000 species and a worldwide distribution, only absent in marine areas. They appear in all terrestrial ecosystems, where they play an important ecological role, for example, forming peatlands, maintaining soil moisture, or being the first colonizers of new habitats.

They are non-vascular plants, meaning they lack a specialized system to transport water from the soil to their aerial parts, which limits the size of the plant to a few centimeters (except in very humid areas), reason why they mainly inhabit moist places. However, many mosses have the ability to dry out and remain in a dormant state until they become moist again, so they can live in dry places and be active only when wetted.

Mosses have a biological cycle in which two generations are needed, and these generations are morphologically very different. The typical moss is formed by the gametophytic generation, with a single copy of each chromosome, which is dominant in the cycle and has a plant-like form, with a stem, leaves, and small roots. These individuals form ovules and sperm, and since the sperm cannot swim without water, mosses need to be wetted to reproduce. After fertilization of the ovules, which are inside structures formed by the plant, the sporophytic phase begins to grow, which has two copies of each chromosome and grows on top of the gametophytic phase at the expense of its nutrients. This phase is nothing more than a filament at the end of which there is a sporangium, which will produce the spores from which the gametophytic phase will germinate. The germination of the spores forms a kind of filamentous network called protonema, on which the moss eventually forms. Thus, the main phase of the moss in higher plants has evolved to become pollen or the structures that encase the ovules, while the sporophytic phase that has a sporangium at its end would be the one in higher plants corresponding to the plant itself.

The following image represents a typical cycle:
 

 

The next cladogram shows the evolutive relations of the different classes of the phylum Bryophyta:

 

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