Sambucus, breathing through the cork layer

Cork is formed by a cambium layer that itself almost always arises as secondary meristem from the collenchyma or parenchyma layer directly under the epidermis. Unlike sclerenchymal cells, collenchymal cells are still alive and have retained the ability to differentiate. Cork cambium cells only divide periclinally, creating the typical rows of daughter cells. In this way mainly cork cells are produced to the outside and to a much lesser extent (sometimes not at all) cork parenchyma is produced to the inside. Cork cambium, cork cells and cork parenchyma together are also called periderm. Developed cork cells are dead and their cell walls contain suberine, a greasy substance that repels water.

Chloroplasts - the solar panels of the plant cell

We have known for many years that plants get their energy from the sun. But turning sunlight into usable energy requires some special hardware, and this is where chloroplasts come in. Chloroplasts are microscopic structures present in most plant cells. In fact, they are present in such high numbers that you can see them without a microscope as the green color of plants. The chloroplasts green color is due to the presence of a green pigment called chlorophyll, which absorbs both red and blue lightwaves from the sun and reflects green light giving the pigment its green color. The red and blue sunlight (energy) absorbed by the molecule is then able to drive photosynthesis which happens in the chloroplasts.

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)

It looks like a miniature pine forest

Hippuris vulgaris or Marestail is a common swamp and pond plant. This plant is counted among the oxygen plants because the underwater leaves also produce a lot of oxygen and it resembles Elodea (waterweeds) The piece that is a few decimeters above the water looks like a small pine tree. Marestail can form large masses and propagate by means of rhizomes. It prefers to grow on clay soil and in particular in brackish water. A Marestail field looks like a miniature pine forest.

Euglena - part plant, part animal

Cells with a nucleus are called true cells, or eukaryotes, which can be further subdivided into kingdoms like plant and animal. Plant cells and animal cells are different in their components and structure, but some organisms does not fit as neatly into these little boxes and can be tricky to place on ‘the tree of life’. One of these is the single celled organism euglena.

Euglena with clearly visible red eyespots

A beacon for sailors

In an earlier publication, photos have already been shown of a tree species that belongs to the Casuarina family. In this case, a photo was taken of the cross-section of a needle with a DAPI long-pass fluorescence filter, which gives a nice image.

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).

Mysterious crystal growth on tiny crustaceans

Crustaceans form a large group in the animal kingdom, and most are familiar with some of the larger members like crabs, lobsters, and shrimps. But many crustaceans are a lot smaller than those, and make up an important part of the food chain as food for fish and other larger animals. One of these planktonic species is daphnia magna, and with a size of 1.5 to 5 millimeters it is one of the largest in its family and just visible with the naked eye. However, it is not the daphnia itself we will focus on today. But a strange phenomenon that occurs on its body, as well as on a few other tiny crustaceans like it.

Female Daphnia magna carrying the next generation in a cavity.

Water worms

When searching for macro fauna in a small pool in the province of Limburg, The Netherlands, the worms on the video were found alongside many other organisms. These worms belong to the Oligochaeta, a subclass within the ringworm taxonomy. There are species that live in the soil on land and species that live in the water.

Oligochaeta are well-segmented worms and most have a large body cavity that is used as a hydro skeleton. Usually each segment has little bundles of chaeta or ‘bristles’ on the outside, The bundles can contain one to several hairs and contain muscles to pull them in and out of the body. This allows the worm to get a grip on the ground or mud while it nestles into it. When digging, the body moves peristaltically, alternately it contracts and stretches forward.

Stentors - some of the largest single celled organisms in the world

Stentors are trumpet shaped single celled organisms found in freshwater habitats like pods and streams. Due to their shape they are more commonly known as trumpet animalcules. Stentors are some of the largest single celled organism in the world, with the largest species reaching a size of up to two millimeters, and it is therefore possible to spot them in a water sample without a microscope. Stentors are ciliates, which mean that they move and feed with tiny hair-like projections called cilia. They have a large number of these cilia surrounding the mouth which creates a current of water carrying food particles for ingestion. In the opposite end they have a foot which is they use to adhere to a substrate.

Observe the classic trumpet shaped appearance and the clearly visible cilia surrounding the mouth.