2019

The Club Moss - Common and Protected

Millions of years ago, our planet was covered by spore plants: ferns, horse-tails and club moss. It is known that these ancient terrestrial plants reached their peak in the Carboniferous Period, when the Earth's climate was particularly favourable to them, much warmer and more humid than today. The dominance of spore plants ended about 300 million years ago. Coal and brown coal beds are a "memory" from that time.

The coal remains indicate that the ancient spore plants were large natural formations that, at tens of metres in height, formed primeval forests. Even prehistoric horse-tails used to rise up to 15 metres above the ground. Ferns were even taller. However, the club moss was the most majestic plant of all, which could reach 40 metres in height and 5.6 metres in diameter. It is hard to imagine that these primitive plants, whose modest descendants can often be seen in the woods today, were even taller than trees.

Forest - home to the club moss

Modern club moss has little resemblance to their extinct gigantic ancestors. However, when we look closely, we can see that the club moss in the woods is not so short at all, sometimes its trunks can exceed 5 metres. True, these trunks do not stand out with an impressive diameter and do not aspire to the sky at all; they are thin and twine on the ground.

The cord-like trunks of the modern club moss are attached to the substrate by roots. Steep branches adorned with many small leaves rise from their "creeping" trunks.

In Latvia, club moss can be seen in all its glory at any time of the year, as this is an evergreen herbaceous plant that maintains its trunk and leaves also throughout winters. Of course, when you go looking for it, you have to go to the woods - the home of the club moss.

Reproduces with spores

The process of development of these plants is characterized by a distinct generation change. Two generations are distinguished: the asexual or diploid (sporophytic) generation and the sexual or haploid (gametophyte) generation. The asexual generation predominates - during its period the club moss has a well-developed green surface and root system. 

At the end of the summer, elongated spindles, called strobili (sporophilic assemblages), develop at the tips of the asexual generation club moss. Strobili consist of assemblies of sporangia, which develop water-resistant spores. Spore concentrate in strobili is a fine, gentle but greasy, non-drying oil powder. The colour of this spore powder is yellow, so strobili that contain it, which are always green at the start of their formation, turn yellow before the spores break out.

Three species

The Lycopodium genus in present-day Latvia is represented by three species: Lycopodium clavatum, Lycopodium annotinum and Lycopodium dubium. Lycopodium clavatum and Lycopodium annotinum are relatively common, but Lycopodium dubium is much less frequent.

Lycopodium genus belongs to Lycopodiaceae family. This family also includes the genus called Diphasiastrum, of which there are two species common in Latvia - Diphasiastrum complanatum and Diphasiastrum tristachyum, and the genus called Lycopodiella, of which we can find one species in Latvia - Lycopodiella inundata.

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Common and protected

Although the majority of the club moss belonging to the Latvian flora is not rare, all of them are protected by law in our country. These plants have a complex development process and a very long period of development. It takes at least 3 years after the spores are sown and enter the soil until it finally germinates. The sexual generation cycle (gametophyte) begins: it develops a small (only about 1 to 2 centimetres long), green leaf - the prothallium.

During the early stage of development of the prothallium, when it is composed of only 4 to 5 cells, a symbiontic fungus is introduced, creating mycorrhiza (coexistence with trees), which provides nourishment for the prothallium. If this fungus does not develop, the prothallium will cease to function.

Even when the conditions are normal, the prothallium grows slowly and does not mature until 6 years. Male and female reproductive organs develop on the surface of the prothallium. After maturation, the gametes converge to form a zygote - the first cell of the next sporophite (asexual generation club moss). The sporophite germ is formed. First it dwells beneath the ground for a good while, then creeps to the surface and begins to green, gradually forming a creeping stem and roots, then vertical shoots or branches with leaves. When the vertical shoots of the plant reach the age of 6-7 years, they begin to mature spores. The following year, these shoots die.

Depending on various conditions, the complete cycle of development of the club moss or "spore-to-spore" development is 20 to 30 years.