Bryophytes and pteridophytes

Did you know....(Pteridophytes)

Sweet root, sweet fern, sweet bracken and liquorice are some of the names given to the fern, common polypody. We can often recognize plants’ distinguished characteristics in their folk names. You may wonder whether the common polypody is actually sweet? A crawling underground stem of the common polypody contains osladin, a chemical compound that is 500 times sweeter than sugar.

Clubmosses are the oldest living land plants that appeared 410 million years ago, and have barely changed since then, so we call them the living fossils. They were dominant in the Carboniferous, when they built rich swamp forests with the species up to 40 metres tall. Most of the clubmosses are extinct, and today they make up the largest part of pit-coal layers in Europe and North America.

How did the pit coal occur? 250 to 300 million years ago, under high pressure, without any oxygen and under high temperatures, pit coal developed from the remains of giant ferns that used to grow in swamp forests. Nowadays, ferns reach quite a lower height. Our biggest fern is the bracken fern, whose leaves can reach the height of over 2 metres.

Horsetails are characterized by a jointed and hollow stem (a) which has side branches in the shape of a ring (b). The leaves (c) are tiny and plain and they wrap in the stem above each sheath (d). Most horsetails will have a distinguished spring stem (1),  a brown and non-extended stem which carries strobilus with sporangia on its top (e) and a summer, green stem (2). There are 9 horsetail species in Croatia.

BRYOPHYTES AND PTERIDOPHYTES

The rocks in the Trakošćan Park Forest are thickly overgrown with moss in some places, and we can often find various fern species in the forest's shady areas. What do we know about them?

Bryophytes and pteridophytes appeared on Earth about 420 million years ago. Bryophytes are the first more complex land plants which haven't completely adapted with their structure to life on land. They have a poorly developed waxy cuticle, which is a protective layer that covers the plant's surface and prevents the water loss. They do not have real plant organs, nor do they have conducting vessels for the transfer of water and nutrients across the plant. They need a lot of water to survive, so we can mainly find them in shady and wet habitats. They usually grow in dense groups, forming soft forest carpets, or covering the tree's bark or even house rooftops, but we can also find them in the water where they serve as food for fish and many other animals.

Although the largest bryophyte is only 50 centimetres tall, and some are so small that you have to crawl down to find them, they are very important inhabitants in various habitats. They participate in creating the humus, they loosen the soil, prevent erosion of the ground, and they also act as a sponge – by absorbing and retaining water which is then made available to other organisms. Bryophyte turfs are full of life: they are a home for numerous tiny invertebrates and bacteria.

Pteridophytes are the first real land plants. They are built of root, stem and leaves, and have a developed conducting system. Pteridophytes, as well as bryophytes, appear on all continents, and they are most dominant in wet and warm habitats.

Bryophytes and pteridophytes are disseminated by wind, with the help of small and light spores that are developed in sporangia. Each moss unit contains a sporangium or pouch, whereas the ferns have a structure of more sporangia in groups or sori placed at the bottom part of leaves. Bryophytes and pteridophytes have a complex life cycle, but what they have in common is that they can all reproduce asexually or sexually. They need water for sexual reproduction, which limits their expansion and domination among the land plants

Did you know.... (bryophytes)

Conocephalum conicum is a species of bryophyte that belongs to the group of liverworts. How did the liverworts get their name? It used to be considered that liverworts cured liver diseases, and some of them even look like liver by their body structure. 

Peat-cutter mosses (mosses from the order Sphagnum) build the vegetation of bogs, which are habitats characterized by low quantity of nutrients and low pH value. Acidic soil prevents decomposition, so the mosses accumulate in the shape of a peat, from which the peat coal is developed. Peat is used as a supplement to gardener's soil when pot-plants are grown in the acidic soil.

Bogs are typical vegetation in the northern and Atlantic Europe. Croatian climate conditions are unfavourable to them, thus they are rare and threatened with extinction. We can find bogs in Dubravica in Hrvatsko Zagorje, in Blatuša, Gorski Kotar and Sunđeri on Velebit. 

Bryophytes on the trees' bark, easily absorb and permanently accumulate chemical compounds which pollute the air, so they can serve as bioindicators for air pollution.

In karst waters, there are moss species that participate in sedimentation of limestone from water, and in creating waterfalls and barriers – recognizable characteristics of our national parks ˝Krka˝ and ˝Plitvička jezera˝.