Montag, 30. Juli 2012

Field Trip to the Phoenixsee in Dortmund-Hörde

Last week, I participated in a Field Tripp to the “Phoenix See”. This is an artificial lake in Hörde, which is an urban district of Dortmund; a large town in Western Germany and part of the “Ruhrgebiet”.

1) The History of Hörde

Originally a separate city, Hörde was first mentioned in 1198, as a part of the County of Mark; a county of the Holy Roman Empire. During this time, the castle of Hörde was also built. In 1340, the city was officially founded by Konrad von der Mark, the earl of Mark, who gave Hörde town privileges. The Earl wanted to encircle his enemy, the town of Dortmund, by placing his own cities around it. Other examples for this strategy were the foundings of Bochum, Witten or Unna.

Burg Hörde (Castle Hörde) - built in the 12th century

The rivalry between the County of Mark and the City of Dortmund culminated in the “Dormunder Fehde”; a vicious feud, which lasted from 1388 to 1390. During this feud, many cities in the area were burning but Hörde and its castle were never conquered. A predisposing factor was certainly the location of Hörde in the swamps of the river Emscher.

After the death of Count Dietrich I., the last count of Mark, Hörde became part of the new county Kleve-Mark, which was founded at the end of the 14th century. Throughout the 15th century, the history of city was dominated by the disputes of the heirs of Kleve and Mark and the strained relationships with Dortmund.

Ruderal wasteland - typical for this area

In the 16th cenutry, Hörde was nearly destroyed by several, serious fires. At the end of the century, the town was occupied by the Netherlands for a time.

Like many cities in central Europe, Hörde suffered severely from the Thirty Years War; a brutal conflict, which devasted the continent from 1618 to 1648. The reason for this misery was not directly the war and its battles, but in the Thirty Years Wars, many cities like Hörde were looted by the armies of the parties of the conflict. Their troops came into a city and took everything they needed. So, the inhabitants suffered from hunger and diseases. During this time, Hörde was occupied by Troops from Spain, Sweden and the Holy Roman Empire.

In the second half of the century, there was no peace for the city, because it was occupied again by French troops during the Franco-Dutch-War from 1672 to 1679.

Phoenixsee 2012

The 18th century was the age of absolutism and this also applied for Hörde. The consequences were extensive restructuring of the administrative districts in the whole German Empire. During this time, the first coal mines were built in Hörde, but the town was also a centre of the nail production.

At the beginning of the 19th century, Hörde, like the most parts of the Ruhrgebiet, were conquered by French troops under the command of Napoleon. The Occupation lasted from 1807 to 1813. The French founded the new Department of Dortmund and Hörde became a part of it.

After the End of the German campaign of the Napoleonic Wars (“Befreiungskriege”) in 1815; Hörde became part of the Department “Westfalen” with Dortmund as capital city. This era was also the beginning of the rise of the montane industry in Hörde. First, the focus was on mining, but in 1840 a businessman named Herman Dietrich Piepenstock, who also bought the castle, founded the “Hermanshütte”, an ironwork company, which open in 1942. After the death of Piepenstock, the “Hermannshütte” was transformed into the “Hörder Bergwerks- und Hütten-Verein” (Hörder Mining and Ironwork company), which was in operation until 2001.

The "new" Emscher

During this period, steel production increased rapidly and the city became a center of high-performance processing of steel at the beginning of the 20th century.

In 1928, the city became part of Dortmund, what marked the end of Hördes history as independent town. However, the processing of steel continued until 2001,. when the company was closed and parts of its machines were sold to China, where they are still in action today.

2) The Phoenixsee

Phoenixsee - look to the south shore

 After the closure of the steelwork company, the local government was looking for new uses of the area. The main problem of many towns in the “Ruhrgebiet” was their high specialization in mining and montane industry. With the closure of many mines and factories, large parts of the city became desolated. The remains of the old factories became rusty ruins and many people had no jobs. To solve this problem, the governments of the cities developed a plan for the resurrection of the Ruhrgebiet. The main points of this change were

  • the development of a new industry with new jobs
  • the removal of the old industrial plants in order to create new space
  • the renaturation of areas, which were polluted by the heavy industry

In some cases, the old factories became museums or monuments. The most popular example for this is probably the famous “Zeche Zollverein” in Essen; other examples are the “Landschaftspark Duisburg-Nord” in Duisburg or the “Gasometer” in Oberhausen.


In Hörde, the “Hermannshütte” was demolished and on its place, a lake was created as recreation area. This lake is the Phoenixsee, which was completed in 2011 after five years. The new lake has a total area of 24 ha and a length of nearly 1230 metres. The lake is about 310 metres wide and nearly 5 metre deep.

But the Phoenixsee isn't the only important waters in this area. The other one is the Emscher. The Emscher is one tributary of the Rhine and flows parallel to the Ruhr. For a long time, the Emscher was nothing more as a sewer and heavy polluted by the industrial wastes. After the closure of the factories, a restoration project was started. The main goal of this project is to give the Emscher a semi-natural state.

 Ruderal wasteland at the Southshore

3) The Field trip

The field trip could be divided into three sections. We started at the Castle of Hörde and looked at the industrial wastelands around it. Later, we moved on until we reached the Emscher and the Phoenixsee. The field trip ended with a second, small industrial wasteland.

the renaturated Emscher

It should be said that many plants at the shores of Emscher and lake were planted, because a natural revegetation would be impossible in such a short time. However, these plants are similiar to the original vegetation.

4) Species

5) Pictures


Apera interrupta 
 Asplenium scolopendrium

Buddleja davidii
Cirsium vulgare

Epilobium angustifolium

Galeopsis tetrahid

Helianthus anuum

Hordeum jubatum

 Lathyrus prantensis

Plantago uliginosa 

Poa palustris

Polygonum lapathifolium

Rumex rugosus

Sedum album

Senecio vulgare

Senecio inaequidens

Silene noctiflora 

Solanum decepiens

Tanacetum vulgare

Trifolium hybridum

Tussilago farfara

Juncus effusus

Lythrum salicaria

Ranunculus sceleratus

Schoenoplectum tabernaemontani

Typha angustifolia


Metrioptera roeselii - Roesels bush cricket

 Argiope bruennichii - Wasp spider

Montag, 23. Juli 2012

Plant of the Day (July 23rd, 2012) - Carex hirta L.

This time, I've a new sedge for you. This sedge is Carex hirta L. from the Cyperaceae family. In English, this plant is known as “hairy sedge” and in German as “Haarige Segge” (means the same) or “Raue Segge” (rough sedge).

C. hirta - habitus

It's a grass-like, perennial plant, which can reach heights between 20 and 70 centimetres (7,8 to 27.5 feet). Some individuals also reach a maximum height of 100 centimetres (39.4 feet).
The well-foliated stalk grows upright and is triangular, what's typical for sedges. There are also long rhizomes.

C. hirta - you can see the hairs on stalk and spikelets

The long, narrow leaves are covered with hairs (in some rare cases, the leaves can also be bald) and have a blue-green colour. At the base of the stalk, there are also some small, brown sheaths. Another distinctive feature are the long bracts, which overtopping the inflorescences clearly.

C. hirta  - inflorescence

C. hirta belongs to Heterostachyae; so male and female spikes look different. The male spikes are cylindrical and about 30 millimetres long.
They are located at the end of the stalk. On the other hand, the female spikes are wider and arranged along the stalk. Their bright green beaks are between 5 and 7 millimetres long and taper toward the tip.
Flowering time is between April and July. The seeds are spread out by the wind, by water and by animals.

C. hirta - infloerescence (closer look); you can see here
the hairs and the long beaks

All parts of C. hirta are more or less hairy;, what makes this species to one of only a few sedges with so many hairs. This is also the reason for the name ("hirta" means "hairy").

C. hirta is native to Europa and Asia (except from the High North and Asia minor. It can also be found in North America and New Zealand as Neophyte. This sedge grows on fresh, nutrient-rich soils and likes warm, sunny to semi-shady places. Such places are e. g. meadows, ruderal wastelands and pastures

Dienstag, 17. Juli 2012

Plant of the Day (June 17th, 2012) - Scrophularia nodosa L.

Today's “Plant of the Day” is Scrophularia nodosa L. from the Scrophulariaceae family. This species is known as “Knotige Braunwurz” in German and as “figwort” in English.

S. nodosa - habitus

It's a herbaceous plant, which can reach heights between 50 and 100 centimetres (19.7 to 39.5 inches). The quadrangular stalk grows upright but there are also underground rhizomes. These Rhizomes have many nodes, what is also the reason for the Latin name of this species (“nodosa” means “nodular”).

S. nodosa - leaf

The bald, dark-green leaves are arranged in a decussate leaf-pattern. They have a long petiole, a strongly serrated margin and a shimmering ventral side. The basal leaves are heart-shaped, while the bracts are egg-shaped. Crushed leaves smells very unpleasant.

S. nodosa - inflorescence

The inflorescence is a loose panicle. The globular flowers are about 8 millimetres long. They are multicoloured with a green base, a reddish brown to purple top and a green-white lower lip. The primary pollinators of these distinctive flowers are bees and wasps but also hummingbirds. Flowering time it between June and September. The ripe fruits are globular, bald capsules.

S. nodosa - flowers

S. nodosa is native to Europe an Eurasia, but can also be found as Neophyte in North America. It prefers wet, nutrient-rich soils in the penumbra. So, it grows e. g. at brooks, forests and riverbanks. In past, this plant was used to cure Lymphadendopathy and other kinds of engorgements. Because of the nodular rhizome, healers suspected, that S. nodusa can cure such diseases.

Freitag, 13. Juli 2012

Plant of the Day (July 13th, 2012) - Salix alba L. var. alba

Today's “Plant of the Day” is Salix alba L. from the Salicaceae family. The English name of this species is “White willow” and in German, it is called “Silber-Weide” (silver willow). It's also the largest willow in Germany.

S. alba - leaves, bark and brances

It's a tree, which can reach heights until 35 metres (114.8 feet). So, S. alba is one of only a few willows, which grow as trees (the most willows are large shrubs). The bark is greyish and deeply furrowed. Young branches are very elastic and have a yellowish to brown colour. They are also hairy, but loose these hairs, when they get older

The leaves are lanceolate with the widest point in the middle of the leaf-blade. Their dorsal side is covered with some small, white hairs. The ventral side is much hairier than the dorsal side; the hairs are also much longer. Because of this, the leaves seem to shimmer silver. The margin is a little bit serrated and all leaves have a petiole, which is until 5 millimetres long.

S. alba - leaves (dorsal & ventral side)

S. alba is dioecious, so we have male and female individuals. However, in both cases, the inflorescences are cylindrical catkins with a maximum length of 7 centimetres The stamens have a hairy base and the carpels are bald and short-stemmed or sitting, which is different from plant to plant. The bracts are yellow and hairy at the base but bald at the top. Flowering time is between April and May. The ripe fruits are spread out by the wind in June.

S. alba - female catkin

This species is native to Europe, Central Asia and North Africa. It grows in wet, flooded areas like riparian forests, riverbanks or oxbow lakes. As you can think, S. alba prefers sandy, nutrient-rich soils and bright places to grow. It's also a very popular ornamental tree for parks or cemeteries. In this case, the most popular sort of S. alba is “Tristis” (“weeping willow”) with its strong overhanging branches, which symbolize mourning.

The bark of S. alba contains Salicin, which is a very good analgesic. So in earlier times, the bark was used to cure illnesses like rheumatism, gout and even fever. The pliable branches are also used for basket weaving.

Montag, 9. Juli 2012

Plant of the Day (July 9th, 2012) - Filipendula ulmaria (L.) Maxim

Today's “Plant of the Day” is Filipendula ulmaria (L.) Maxim; a member of the Rosaceae family. In German, this plant is known as “Echtes Mädesüß”, while common English names are e. g. “meadowsweet”, “meadwort” bridewort” or “Queen of meadow”.

F. ulmaria - habitus

It's a perennial plant, which can reach heights between 60 and 200 centimetres (23.6 to 78.7 inches). The stalk grows upright. Only its upper regions has branches The whole stalk is slightly angular and bald.
The leaves are pinnate with 2 to 5 leaflets per leaf. The leaflets remind a little bit to the leaves of an elm (Genus: Ulmus), what is also the reason for the Latin name “ulmaria”. The basal leaves are arranged in a rosette; the upper leaves have a long petiole. All leaves are bald to slightly felty.

F. ulmaria - leaf

The inflorescences are umbel-like racemes. The small flowers are radial. The sepals are green and the petals white to cream-coloured; flowering time is between June and August.
The ripe fruits are small, bended nuts, which grow in groups of six to eight fruits per flower. This makes them seem like a single, spirally -grooved fruit.

F. ulmaria - inflorescence

F. ulmaria is native to Europe and Asia but can also be found in North America as neophyte. It likes nutrient-rich and wet to waterlogged places. So, this species grows e. g. in carrs, bogs, at riverbanks or on wet meadows but also in ditches.

watterlogged place are a typical habitat of 
F. ulmaria

The flowers of F. ulmaria have a strong, sweet odor. Meadows with this plant smell very pleasant what is also the reason for the name “meadowsweet”. This odor is caused by the many ingredients within this species. These include essential oils, Flavonoids or Salicylic acid. Thereby, the plant was used in past as febrifuge.