Freitag, 29. Juni 2012

Plant of the Day (June 29th, 2012) - Potentilla reptans L.

Today's “Plant of the Day” is Potentilla reptans L. from the Rosaceae family (Sub-family: Rosoideae). In Germany, we call this plant “Kriechendes Fingerkraut” while in English, it's known as “creeping cinquefoil” or “creeping tormentil”.

P. reptans - habitus

As the name suggests, it's a perennial plant with a creeping stalk (“reptans” is Latin for “creeping), which can reach a total length of 1 metre (39.3 inches). But because of the creeping growth, the maximum height of this plant is only between 10 and 20 centimetres (4 and 8 inches). The leaves have a very long petiole and are digitate with 5 to 7 “fingers” (leaflets). Each leaflet has a rough sawn margin.

P. reptans - leaves

The inflorescence consists of single, terminal flowers with long stalks. Each flower is radially and has five sepals and petals. The petals are golden-yellow and inverted heart-shaped. So, their apex is broader than the base and also a little bit indented. Flowering time is between June and August.

P. reptans - flowers

P. reptans is native to whole Eurasia and prefers, fresh, nutrient-rich soils. So, it can be found on fresh places like riverbanks, fresh meadows but also ruderal wastelands and embankments. It is also planted on walls for greening.

Montag, 25. Juni 2012

Plant of the Day (June 25th, 2012) - Heracleum mantegazzianum Somm. et. Lev.

Today's “Plant of the Day” is one the most notorious plants at all. I'm speaking of Heracleum mantegazzianum Somm. Et Lev. from the Apicaceae family. In Germany, this species is known as “Bärenklau” or “Herkulesstaude”, while English names are “giant hogweed”, “wild parsnip” or “giant cow parsley”. In older literature, this plant is still known as Heracleum giganteum.

H. mantegazzianum - habitus

It's a large perennial plant, which can reach heights between 2 and 3,5 metres (6.6 to 11.5 feet). The hollow stalk grows very fast and H. mantegazzium can reach these heights within a few weeks after sprouting. The stalk is very strong with up to 10 centimetres in diameter at the base. It's very hairy and also speckled purple.

H. mantegazzianum - stalk

The leaves are pinnate with 3 to 5 digitate “leaflets”. As the rest of this plant, they have an impressive size with up to 1 metre. Their sheaths are also very conspicuous and remain as a leathery structure at the leaf base.

H. mantegazzianum - leaflet

The inflorescences are umbels. These umbels can have up to 50 centimetres in diameter and can consists of 30 to 150 small flowers (you see, it's a very imposing plant). The flowers in the periphery of an umbel are normally larger than the flowers in the centre. Each flower has five white petals, which are indented a little bit. Flowering time is between June and September. The ripe fruits are shizocarp, what is typical for the Apiaceae. They are disk-shaped and their edge rips are bristly.

H. mantegazzianum - umbel

H. mantegazzianum is native to the Caucasian, but was brought as ornamental plant to Middle Europe in 1900. Later, it starts to grow wild and spread out along roads and rivers. So today, you can found this species e. g. on ruderal wastelands, at roadsides or in river valleys. It's very undemanding towards the soil but likes nutrient-rich, not so acid places.

H. mantegazzianum - sheaths

As fast growing neophyte, H. mantegazzianum could be a great threat for native biodiversity, because it has the ability to overgrow places and to displace other species quickly. However, H. mantegazzianum is not such a large problem like e. g. Fallopia japonica (Japanese knotweed) or Robinia pseudoacacia (Black Locust). Regular mowing is a good way to fight large stocks of this species.

H. mantegazzianum - stalk with hairs

However, in popular culture, H. mantegazzianum is one of the most feared plants. The reason for its bad reputation are the ingredients of the plant.
All parts of H. mantegazzianum contain a phototoxic liquid, which is dispensed by the hairs. This liquid reacts with UV radiation, what triggers a chemical reaction, which can caused serious burns. So, it's not a good idea to touch this plant with bare hands. To avoid contact with the skin, people should always wear protective clothing, if they want to remove plants.

Freitag, 22. Juni 2012

Plant of the Day (June 22nd, 2012) - Veronica teucrium L.

Today's “Plant of the Day” is Veronica teucrium L.; a member of the Plantaginaceae family. In English, this species is known as “Large Speedwell” while the common German name is “Großer Ehrenpreis”.

V. teucrium - habitus

It's a perennial herb, which can reach a height between 30 and 100 centimetres (11.8 to 39.3 inches); making it to one of the largest, middle European speedwells, which is also the reason for its name. The round stalk is hairy all around. The leaves are sitting directly at the stalk. They are egg-shaped and have a very strong serrated margin. 

 V. teucrium - leaves and stalk (note the hairs)

The inflorescences of V. teucrium are terminal, stalked racemes. The flowers are a little bit zygomorphic and remind to a supper. They have one large and one small petal, what is typical for the Genus Veronica. All petals are sky blue with distinct dark veins; the sepals are green and very narrow.
It's also interesting, that V. teucrium has five sepals but only four petals (some species of the Genus Veronica still have a tiny, fifth petal as vestige). Flowering time is between May and July.
The ripe fruit is a hairy, spade-shaped capsule.

V. teucrium - inflorescence

V. teucrium is native to Middle Europe and Eurasia. Its areal spreads from the North Sea in the North to the Balkans in the South and from France in the West to Siberia in the far East. However, within this area, it grows very scattered and is more frequently in one area than in others.
The species prefers warm, relatively dry places on shallow, loamy soils. It can be found on meadows, in bushes or at the edges of forest.

Because of the large, beautiful flowers, it's also a very popular garden plant, which attracts bees and bumblebees.

Freitag, 15. Juni 2012

Plant of the Day (June 15th, 2012) - Anagallis arvensis L.

Again, another species, which I found during my Field Trip to the Rhine shore, should be today's “Plant of the Day”. This species is Anagallis arvensis L. from the Primulaceae family (Sub-Family: Myrsinoidae) In German, this plant is known as “Acker-Gauchheil”, while other common names are “Nebelblume”, “Wetterkraut” or “Roter Weinbergstern”. In English, this plant also has a lot of different names like “Red pimpernel” “Shepard's clock” or “Poor man's barometer”.

A. arvensis - habitus

It's a small herb, which can reach heights between 5 and 30 centimetres (2 to 11.75 inches). The bald stalk grows creeping or upright. The leaves are egg-shaped or oval with an average length of 25 millimetres and an average width of 14 millimetres. They sit directly at the stalk.

A. arvensis - leaves

The inflorescences of A. arvensis are single, radial flowers with five sepals and petals. The petals are brick-red (blue at some subspecies) and covered with small glands. Flowering time is between May and October. Each flower has a special opening cycle, which depends on daytime and weather (see below).
The ripe fruit is a capsule with 22 seeds.

A. arvensis is native to the Mediterranean but can be found all over the world today . It prefers loamy, nutrient-rich soils and grows e. g. on ruderal wastelands, in Gardens and vineyards or on fields.

A. arvensis - flower

This species has a lot of names, which refer to its special properties or past uses. Here are some examples.

Acker-Gauchheil: “Acker” is the German word for “field” and refers to the typical growing place. “Gauch” is an old German word for a madman, while “heil” means “to cure”. In past, A. arvensis was used (unsuccessfully) to cure madness, which is the reason for this German name.

Shepard's clock, Poor man's clock: these names refer to the special, daily flowering cycle of the the flowers, which are open between 9 o'clock in the morning and 3 o'clock in the afternoon.

Wetterkraut, Nebelblume, Poor man's barometer: another special feature of the flowers is to close themself before rain. So, A. arvensis was used in past for weather forecast. This is the reason for these English and German names.

Montag, 11. Juni 2012

Plant of the Day (June 11th, 2012) - Lotus corniculatus ssp. hirsutus Rothm.

This time, I want to present a new species from the Fabaceae family. This species is Lotus corniculatus ssp. hirsutus Rothm. In Germany, we called this plant “Behaarter Hornklee” while the common English name is “Hairy Birds-food trefoil”. In Switzerland, this plant is known as “Schotenklee”.

L. corniculatus ssp. hirsutus  - habitus

It's a herb, which can reach heights between 10 and 50 centimetres (3.9 to 19.7 inches). The angular stalk grows upright or creeping and has an inner medullary. The leaves are imparipinnate with five leaflets. The lower pair sits directly on the stem, so in some literature, these leaflets are termed as stipules. All leaflets are inverse egg-shaped. Both Stalk and leaflets are covered with hairs, which gave the plant its scientific name (“hirsutum” means “hairy”). This is also the main difference to the other subspecies Lotus corniculatus ssp. corniculatus L.

 L. corniculatus ssp. hirsutus  - leaves and angular stalk
(here you can see the hairs on the leaves

The inflorescence is umbel-shaped with three to eight flowers. These flowers are the typical cygomorphic flowers of the Fabaceae. The golden-yellow petals are divided into “wings”, “keel” and “banner”, which consists of two fused petals. The sepals are hairy and form a bud before flowering. The ripe fruit is a curved pod. 

L. corniculatus ssp. hirsutus  - inflorescense
( 1) = banner; 2) = wings; 3) = keel; 4) = sepals)

L. corniculatus ssp. hirsutus is native to Middle and Southern Europe and Eurasia but can also be found as Neophyte in North America. It prefers warm places and grows on meadows, embankments, pastures and at roadsides. As Fabaceae, this plant has the ability to fix atmospheric nitrogen and is able to settle on very nutrient-poor soils.

All parts of this plant contain derivatives of cyanide. However, these derivatives are not toxic for humans and other mammals but for snails. In this way, young exemplars of L. corniculatus ssp. hirsutus protect themselves against grub by snails.

Samstag, 9. Juni 2012

Plant of the Day (June 9th, 2012) - Carex muricata L.

Today's „Plant of the Day“ is Carex muricata L. from the Cyperaceae family. In English, this plant is known as “Squarrose-Sedge” and as “Sparrige Segge” and (in past) “Stachel-Segge” in German.

C. muricata - habitus

It's a grass-like herb, which can reach heights between 40 and 90 centimetres ( 15.75 to 35.5 inches). The stalk grows upright and in dense stocks. As with the most species from the genus Carex, the stalk has a triangular shape. It's also a little bit rough. The leaves are 2-4 millimetres broad and have a grass-green colour. Their surface is also a little bit rough.

C. muricata - spikes
The inflorescence is a spike, which consists of 3 to 10 spiklets. These spikelets are between 2 and 4 centimetres long. They grow close together but the lower spiklets may stick out a little bit. Their beaks are between 2 and 5 millimetres long. Each spiklet has two styli. Flowering time is between May and July.

C. muricata - habitus

C. muricata is a very common sedge in Middle Europe and can be found everywhere in Germany. It prefers fresh, sandy soils and grows e. g. in loose forests, on ruderal places or on meadows with many perennials (“Hochstaudenfluren”).

Please note: in my posting about my Field trip to the Rhine, I named this species “Carex spicata Huds.” which looks very similar. However, this was a mistake and “Carex muricata L.” is correct

Montag, 4. Juni 2012

Plant of the Day (June 4th, 2012) - Solanum dulcamara L.

Today's “Plant of the Day” is Solanum dulcamara L. from the Solanaceae family. In Germany, this species is known as “Bittersüßer Nachtschatten” or “Bittersüß”. Common English names are “bittersweed”, “nightshade” or “felonwood”. The reason for this name are the berries. First, they taste bitter, then sweet. “Nightshade” refers to the hallucinogenic effect, which is caused by eating the fruits.

S. dulcamara - Habitus

It's a semi-shrub, which can reach heights between 30 and 200 centimetres (). The stalk can grow upright but also decumbent. In the most cases, this depends on the presence of flowers. Stalks with inflorescences grow upright, while stalks without any flowers grow decumbent. As semi-shrub, the lower regions of the stalks are woody but not the upper part. The leaf-shape varies from leaf to leaf. Some leaves are lanceolate, while others are egg-shaped or have auricles. However, all leaves have a smooth margin, a petiole and are evergreen. The whole plant is bald.

S. dulcamara - flowers

The inflorescence is an overhanging cincinnus (Wickel in German). The flowers are very small with only 1 centimetre in diameter. The sepals are green, while the petals have a violet colour. Their tips are folded back, while stamens are fused to a golden yellow tube, which surpass the calyx significantly. So, the flowers of S. dulcamara have a very characteristic look, which makes it easy to identify the species. Flowering time is from June to August. The ripe fruit is red, egg-shaped berry.

S. dulcamara - flowers

S. dulcamara is native to Europe, Asia and North Africa. It prefers fresh to moist places but can also tolerate dryness. So, it can be found e. g. in riparian forests, wet meadows, shores and ditches. Like most members of the Solanaceae, the plant is toxic through a high content of alkaloids in all of its parts ; especially the berries.

Samstag, 2. Juni 2012

Field Trip to the Rhine on May 25th, 2012

Last Week, I made a little field trip to the riverbanks of the Rhine in my home town of Düsseldorf in Western Germany.

1) Introduction

The Tour starts in the urban district of Bilk at the bottom of the famous “Rheinturm”(Rhine Tower), which is a characteristic feature of the Düsseldorfer Skyline. Then, I followed the arc-shaped shoreline until I reached the railway bridge in the urban district of Hamm, where my field trip ended.

Rhine at Düsseldorf, Germany

The whole area is also known as Rheinknie in Germany (“Rhine knee”; the name refers to the bendings of the Rhine in this area). All in all, I walked a distance of nearly 4,78 kilometres.

"Hammer Eisenbahnbrücke" (railway bridge) - left side: old
bridge towers from 1970 (bridge blown up by the Wehrmacht on March 1st, 1945)
right side: new bridge, built in 1984 and opened in 1987)

It was more an unspecific field trip, so I hadn't the intention to find some special types of vegetation or rare species. The only “goal” was to walk through the area and to look, what grows here.

2) Area

All in all, the area can be divided into four parts: the riparian forest, the rocky beach, the embankment and last but not least the meadow

a) Riparian forest

Riparian forrest at Düsseldorf City Harbour

In the riparian forest (“Auwald” in German), my field trip started. It grows on a very narrow promontory in the city harbour of Düsseldorf. It's probably a pioneer forest because the “soil” was in fact a mix of rocks and stones. I suspect, that this was a former quay, which was later overgrown by the nature.

So, the forest is also some type of ruderal wasteland in an advanced stage of succession. A lot of plants grow in gaps between the stones or on the poor developed soil. However, because of the proximity of the river, the area is also very wet and sometimes flooded..

Some species, which I found here, were Salix alba L., Solanum dulcamara L., Iris pseudacorus,L. Rumex acetosa L., Carex spicata Huds., Anagallis arvensis L. and Potentilla anserina L.

b) Beach

Rhine shore at Düsseldorf - Rocky Beach

After leaving the riparian forest, I reached the beaches. They are a very popular destination for swimming, basking and barbecue. Because of the sunny day, there were indeed many people at the beach.

The beach can divided into two types: a sandy beach and a rocky beach. The last one is more natural, while the first one was created for the people. In both cases, the soil isn't very deep and often flooded by water. Sands and rocks are not a very good nutrient storage, so the plants gets them mostly from the water.

Rhine shore at Düsseldorf - sandy beach

Beside many, stranded mussels, some plants in this sub-area were Silene latifolia Mill., Euphporbia esula L., Cerastium tomentosum L. (which is a neophyte), Potentilla reptans L. and Stachys sylvatica L.

(c) Embankment

Rhine shore at Düsseldorf - Embankment

These are anthropogenic, rocky slopes, which were created to elevate the land a little bit about river-level or to mark the low water area for ships. They are in direct contact to the river and often flooded. On embankments, you often found some exotics species, because their seeds stranded here and germinated in the gaps between the rocks.

Some species in this area were Ficus carica L. and Carex nigra L.

d) Meadow

Rhine shore at Düsseldorf -meadow at the bridge

The meadow has no direct contact to the river and is elevated by the embankment some metres about river-level. So, this area (especially the soil) isn't so often flooded than the areas before. Unfortunately, I cannot exactly say, which type of meadow it was, but I suggest, it was a wet meadow, which became a pasture and later a ruderal meadow. So, it's probably a typical oat-grass meadow. (Arrhenatherion elatioris)

Species in this sub-area were Lotus corniculatus L., Carex hirta L., Veronica teucrium L., Galium album Mill. and of course Arrhenatherum elatius (L.) P.Beauv. ex J.Presl & K.Presl

3) Species

4) Pictures

a) Riparian forrest

Allie schoenoprasum L.

Anagallis arvensis L.

Carex spicata L.

Salix alba L.

 Sedum album L.

Sisymbrium altissimum L.

Symphytum officinale agg.

Symphytum bohemicum Schmidt. 

Potentilla anserina L.

Oxalis fontana Bunge.

Iris pseudacorus L.

Vicia villosa agg.

Galium album Mill.

 b) Beaches

Cerastium  tomentosum L. - habitus

Euphorbia esula L.

Potentilla reptans L.

Silene latifolia L.

Stachys sylvatica L.

c) Enbankments

Carex nigra L.

Caloplaca citrina (Hoffm.) H. Olivier & Lecanora murals (Schraeb.) Rabenh.

Ficus carica L.

Grimmia pulvinata Hedw. & Sm.

d) Meadow

Ailanthus altissima (Mill.) Swingle.

Carex hirta L.

Lotus corniculatus L.

Rumex acetosa L.

Trifolium pratense L.
Veronica teucrium L.