Luminous wood

On the images you can see a cross section of a thin stem of Tilia showing the annual rings which are composed of Xylem in botanical terms or wood in daily language.

At the beginning of the growing season in a temperate climate, the Cambium will produce larger Xylem cells with thinner walls. These large cells (earlywood) are formed because the tree needs a lot of sap after winter. The earlywood is lighter and more porous. At the end of the growing season, the Cambium will produce narrower cells with thicker walls (latewood). Thus latewood contains more matter and is less porous, so it will look darker. Earlywood and latewood, which are formed during the same growing season, make up one annual ring. The most recent growth rings are situated at the tree's periphery, under the Cambium which is between the wood and the bark.

 

Toxic Taxus baccata

Taxus baccata has deep dark green needles all year round. It is an evergreen tree that is also often used as a hedge. In winter, Taxus bears red fruits that are much loved by birds, but very poisonous to ungulates.

Taxus baccata is usually a sturdy shrub that, if given space, can grow into a tree. Growth is slow but eventually the tree can reach a height of about 15 to 20 meters with a width of 12 to 15 meters. The species is widely used for hedges and also for topiary. Bulbs, cones, columns and even animal shapes are available. Taxus can tolerate very strong pruning, even down to the perennial wood.

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.

Fluorescence a useful phenomenon

Fluorescence microscopy is a variant of light microscopy, which is based on the principle of fluorescence. The property of certain fluorescent substances (fluorochromes) is exploited to absorb light - in this case an FITC-filter was used - and release it again with a different longer wavelength, in this case green. However, there is also the limitation of this type of microscopy, since only samples in which these substances have been introduced or which they naturally contain (auto-fluorescence) can be observed. The fluorescence microscope finds great application above all in biology, biochemistry and biophysics, where it is used for the observation of cell components. because it can also represent structures that are far below the resolution limit. 

Large cattail

Typha latifolia, called ‘large cattail’ in English, is a water plant that is mainly found in eutrophic and acid water, along the shores of ponds, ditches and in swamps. This perennial has an upward and wide-spread growth habit. It is easy proliferating through rhizomes. If planted in a garden pond, locking it in a good pond basket is the message. The leaves are broad, linear and blue-green colored. Large cattail blooms from June to September with double cigar-shaped ears. The male ears are at the top, the female right below. After wind fertilization, the characteristic brown colored ‘cigars' form the female flowers. The seeds of cattail develop from the flowers on the cigars. The seed fluff is normally transported by the wind. The plant is hardy, endures sea breeze, air pollution and has a beautiful winter silhouette.

 

The Dujardin coloring technique

The images shown are taken from a beautifully colored prepared slide from the archives of the Royal Antwerp Society for Micrography. The slide is already several decades old. It shows a cross-section of a twig of the plane tree. In spite of the age of the slide, the colors are still clear and fresh thanks to the use of the simple simultaneous Dujardin coloring method. During the coloring the colors were brought into balance with great skill, showing the various plant tissues. On the fluorescence image the plant various tissues are shown in a different manner.