The horsetail – a widespread group of vascular plants with an interesting history

A great part of our fossil fuels is based on distant relatives from our present horsetails. During the Carboniferous, this group of plants attained almost worldwide distribution: arborescent lifeforms up to 30m. The decay of these trees under anaerobic conditions, later additionally under high pressure and high temperatures finally formed coal, still one basis of fossil energy.

Today the horsetails are worldwide in distribution except for parts of Australasia. In Middle Europe a plant height of 1m is remarkable.

The most conspicuous morphological feature of a horsetail is the segmentation of the shoot into nodes and internodes. This is why these plants are also called the “articulate”.

                                               Equisetum telmateia                       Equisetum telmateia (note the jointed stem)

The Club moss – an all-round talent for scientific education

The Club moss (genus Lycopodium) is a native plant of North and Middle Europe, also occurring in Russia, Asia, North America, even in the mountain areas of tropical Africa.

                        Lycopodium clavatum (source)                                                           (source)

Its dispersal units are spores, growing in kidney-shaped sporangia at the base of specialized leaves. These leaves are aggregated in club-shaped units terminating the upright shoots and give reason for the common name “Club moss”.

The spores are used since the Middle Ages for magic rituals (witches farina, flash powder, etc.), nowadays from fire-eaters, for artificial explosions in shows and in movies. This is because the spores contain up to 50% fatty oil, highly inflammable. It’s like “adding fuel to the fire” if you use them.

LYCOPODIUM SPORES FEATURES

The spores can be used for scientific education in multiple disciplines.

• Microscopy, Episode 1: In first instance the spores of Lycopodium with their reticulate surface (1st one from the right) are aesthetic samples with a marked three-dimensionality. For training the fine focus procedure on a transmitted light microscope, this is a good sample. Note the triangle on the surface (2nd one from the left) which indicates the original spore tetrad (Meiosis).