Plants Alongside and Inside Rivers

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Flowing waters constitute a significant ecological habitat. Plants residing here are adapted to the year-round influence of freshwater. The quality of flowing water, the diversity of currents, and the dynamics of water levels profoundly shape the ecosystem. The richer the habitat, the greater the variety of plants and animals it supports.

By the Water’s Edge

At the water’s edge and on embankments, various plant families thrive. Many of these plants have narrow, elongated leaves. Well-known examples include the Yellow Iris (Iris pseudacorus) and the Water Avens (Geum rivale), which bloom in late spring. From June to early September, you can find Purple Loosestrife (Lythrum salicaria) and Meadowsweet (Filipendula ulmaria). In reed beds, you’ll find Branched Bur-reed (Sparganium erectum) and Narrow-leaved Reedmace (Typha angustifolia). On the damp shoreline, species typical of wetlands can be found, such as Marsh Woundwort (Stachys palustris).

Underwater

Submerged aquatic plants grow within the water. They root in the waterbed and develop leaves underwater. However, their flowers and floating leaves reach the surface. In spring, in the cool temperatures of streams and rivers, these plants might not be very noticeable. But as the year progresses, leaves and flowers become evident. One typical species is the Floating Water Crowfoot (Ranunculus fluitans), characterizing an entire plant community. Other aquatic species include Arrowhead (Sagittaria sagittifolia), Water Starwort (Callitriche), and pondweeds like Floating Pondweed (Potamogeton natans).

Habitat Protection

Habitats along and within water bodies are delicate and vulnerable. Diversity is impacted by activities such as bank and riverbed stabilization, over-fertilization, drainage, channelization, low water levels, and improper maintenance. In Germany, the Bund für Umwelt und Naturschutz Deutschland (BUND) advocates for the enhancement and protection of sensitive habitats along flowing waters. The regional chapter in Saxony, as part of the “Sustainable Recovery” initiative by the Saxon Ministry for Energy, Climate Protection, Agriculture, and the Environment, is examining the potential for second-order watercourses in the rural areas of the Free State. The project aims to provide recommendations for landowners, residents, conservation organizations, and dedicated citizens.

This article was featured in the Flora-Incognita app as a story in the summer of 2023. The app provides intriguing information about plants, ecology, species identification, as well as tips and tricks for plant identification. Why not take a look?

Heterophylly: One Plant – Different Leaves

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The leaves of a plant are often a crucial feature for species identification: the leaf of the Wych Elm (Ulmus glabra) has a serrated edge, the leaves of the Wild Tulip (Tulipa sylvestris) are soft and hairless, and the leaves of the Guelder Rose (Viburnum opulus) are always arranged oppositely. There are many examples of plants whose leaves look so unmistakably that the corresponding species can be confidently identified. However, this does not apply to all plants! Some species respond to environmental influences by changing certain characteristics of their leaf shape, such as the size of the leaf surface or the density of leaf venation.

“Leaf polymorphism” (heterophylly) means that a single plant can have very differently shaped leaves. Some herbs can produce several very different leaf forms, so distinct that they might not be attributed to the same species. A notable example of this is found in some species of the genus Ranunculus, commonly known as buttercups. For instance, the Water Buttercup (genus Ranunculus, section Batrachium) has two completely different leaf forms: the finely divided leaves underwater (submerged leaves) and the roughly three-parted dissected leaves that float (floating leaves).

To understand the phenomenon of heterophylly, one must consider the genetics of the plant. The Water Buttercup has a genotype, a genetic basis for its plant traits, but two different leaf phenotypes (physical appearances). Through years of research, even at the molecular genetic level, scientists have determined which genes need to be activated to initiate the formation of a specific leaf shape. The role of plant growth hormones, their concentrations, and flows that determine the final leaf shape has also been investigated. In the case of the Water Buttercup, the pronounced leaf polymorphism is an adaptation to the environment.

However, there are also examples of leaf polymorphism that remain mysterious to this day, as they cannot be explained by environmental adaptations. Among the early spring plants that push their leaves out of the ground, there is the Goldilocks Buttercup (Ranunculus auricomus agg.). What sets this group of species apart is that the same plant can produce completely different leaf forms, depending on whether it has just emerged from winter dormancy, whether it is flowering, or fruiting.

Within a plant individual, an entire leaf cycle occurs, starting with relatively small and simply three-parted leaves (initial leaves) that emerge immediately after winter. Around April, when the plant starts to bloom, more or less deeply divided leaf forms appear, typically used for species identification. Later in the year, when the plant is fruiting, less dissected leaf forms reappear (summer leaves, final leaves). These resemble the initial leaves but are larger. Why the Goldilocks Buttercup exhibits such leaf diversity within a year remains unclear. An adaptation to the environment, as in the case of the Water Buttercup, could not be demonstrated here.

What remains a puzzle for plant development poses a real challenge for botanical systematists. How can one reasonably morphologically define a plant species like the Goldilocks Buttercup when it constantly changes throughout the year? A tough nut to crack (and a subject of ongoing refinement) even for Flora Incognita!

This article was featured in the Flora-Incognita app as a story in the summer of 2023. The app provides intriguing information about plants, ecology, species identification, as well as tips and tricks for plant identification. Why not take a look?

German Plant Community 2023: Littorelletea uniflorae p.p.

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Habitat of nutrient-poor shallow water

The Floristic-Sociological Working Group declared the highly threatened Littorelletea uniflorae p.p. as the German plant community 2023. They were formerly quite common in the vicinity of clear, shallow heathland pools on sandy and gravelly raw soils or peaty substrates – inconspicuous and well adapted to the special requirements of the amphibious habitat.  Due to human interventions such as nutrient inputs and drainage, as well as the consequences of climate change, Littorelletea uniflorae p.p. is now highly endangered. Many of their habitats have already been lost or significantly reduced. Due to their rarity and need for protection, Littorelletea uniflorae p.p. has also been included in the Fauna-Flora-Habitat Directive of the European Union.

Composition

The plants live near the shore, in a narrow strip between reed beds and deeper water, completely submerged or periodically dry. Water level fluctuations support the development of Littorelletea uniflorae p.p. The plant community is named after the European shoreweed Littorella uniflora (also known as Plantago uniflora depending on taxonomy). It is accompanied by the even rarer delicate white-flowered water lobelia Lobelia dortmanna and the lake quillwort Isoëtes lacustris, which belongs to the quillwort family and is already extinct in parts of Germany (Bavaria and Baden-Württemberg). However, the plant community also includes more commonly found species such as bulbous rush Juncus bulbosus or marsh pennywort Hydrocotyle vulgaris.

Isoëtes

The dominant representatives of this group of plants are also classified as low-growing basic shoot plants (Isoëtes). They all share a strong and enduring basal rosette of narrow leaves with well-developed aerenchyma, which is air-conducting tissue. This adaptation to life in water allows the storage of air in the tissue, giving the leaves buoyancy. This growth form enables the plants to withstand seasonal, pronounced water level fluctuations: longer flooding in the winter months, but also enduring dry periods in late summer.

Finding Littorelletea uniflorae

Fluctuating water levels in very nutrient-poor stagnant waters are rare in Germany, and in combination with the inconspicuous appearance of most species, stumbling upon a population of Littorelletea uniflorae p.p. is highly unlikely. Interestingly, there are old reservoir structures in the heart of Germany where you can find them easily. In the Upper Harz region, in the Clausthal-Zellerfeld area, about 65 dams and water bodies were created between the 16th and 18th centuries. 35 of them are classified as reservoirs and are now operated with fluctuating water levels for nature conservation reasons, long after the end of their economic use. Here, extensive Littorelletea uniflorae p.p. can be found, as well as the equally rare dwarf rush communities with sea strapwort Corrigiola litoralis, Illecebrum verticillatum, or water mudwort Limosella aquatica. If you find Littorella uniflorae p.p., you can collect the badge for the plant community 2023!

For more information, visit the Floristic-Sociological Working Group website: https://www.tuexenia.de/en/events/plant-community-of-the-year/.

 

This article was featured in the Flora-Incognita app as a story in the summer of 2023. The app provides intriguing information about plants, ecology, species identification, as well as tips and tricks for plant identification. Why not take a look?

German Poisonous Plant of the Year 2023: Parsley

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A poisonous kitchen herb?
Every year, the Botanical Special Garden Wandsbek in Hamburg announces the German Poisonous Plant of the Year. After the potato in the previous year, for 2023, it is parsley (Petroselinum crispum). The choice of parsley as the Poisonous Plant of the Year is intended to remind us that even seemingly harmless plants can have their dangers. It is important to be aware of the potential risks and side effects of plants and to use them only after careful research.
Dangerous parsley?
Parsley is a biennial plant that initially forms the well-known, low, basal rosette, which is indispensable in many kitchens. In the second year, the plant develops up to 70 cm tall flowering stems that bear inconspicuous yellowish-green flowers. Toxic seeds develop from these flowers. The seeds contain parsley oil, which contains the phenylpropanoid apiol. Consuming it in high doses can lead to allergic reactions and even liver, heart, and kidney damage.
There’s a badge!
If you identify a parsley plant with your Flora Incognita app this year, you will receive the ‘Poisonous Plant of the Year 2023’ badge for your profile!

This article was featured in the Flora-Incognita app as a story in the summer of 2023. The app provides intriguing information about plants, ecology, species identification, as well as tips and tricks for plant identification. Why not take a look?

Phenology: Midsummer – Long Days, Warm Nights

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When we think of midsummer, we might hear the buzzing of insects, the chirping of birds, or the joyful laughter of children fully enjoying their summer vacations. Midsummer brings us a plethora of outdoor activities and unforgettable moments that will hopefully stay with us for a long time. However, climate change does not spare changes in nature. It is crucial to document specific key points every year to make these changes visible. So, let’s take a closer look at what characterizes the phenological midsummer:

Linden Trees in Bloom

The blossoming of linden trees marks the beginning of midsummer. To differentiate them from winter linden trees, you can examine the leaf hairs: the summer linden has small white hairs on the entire underside of the leaves and on the branches, while the winter linden is only hairy on the veins and in the vein angles on the underside of the leaves. Linden flowers can be collected for tea, and due to their high sugar content in nectar, they are also an essential late food source for many insects.

Ripening of Currants

Ripe currants are the first sweet summer fruits that can be “wildly” harvested in Central Europe. However, modern cultivated varieties are no longer identical to the original Ribes rubrum. To enhance the aroma and optimize cultivation, other currant species were crossed (or the color: White currants are just a color variant of the red ones). Black currants (Ribes nigrum), incidentally, are closer relatives to gooseberries than to red currants and ripen slightly later, depending on the cultivation. The bushes of black currants have a smell that some find “unpleasant.” Nevertheless, an important perfume extract is obtained from the flower buds!

Harvesting Sweet Cherries

Sweet cherries (Prunus avium), also known as bird cherries (the species name reveals it!), belong to the rose family. Particularly popular among children and those with a sweet tooth are the well-known cultivated forms, such as the heart cherry (Prunus avium subsp. juliana), because the wild form Prunus avium L. subsp. avium has tiny, black, and bittersweet fruits. It typically thrives in oak-hornbeam mixed forests and can grow up to over 20m in height. The ripening of cultivated sweet cherries is a significant indicator of midsummer. In 2021, Germany recorded 27,340 tons, Austria 6,210 tons, and Switzerland 4,415 tons of harvest – for comparison: Turkey leads the list of the world’s largest sweet cherry producers with an annual production of 689,834 tons.

Barley Harvest Time

Barley (Hordeum vulgare) belongs to the grass family (Poaceae). With an impressive cultivation history of around 10,000 years, it is one of the cornerstones of European agriculture. Winter barley plays a significant role in phenology. Sown in autumn, it thrives initially in a pleasant 10°C and is often the first crop harvested from the fields, even before other cereal crops. This harvest time is another indicator of midsummer. In Germany, winter barley is cultivated on approximately 1.24 million hectares, while spring barley thrives on only about 0.5 million hectares. Overall, Germany harvests about 10 to 12 million tons of barley annually.

This article was featured in the Flora-Incognita app as a story in the summer of 2023. The app provides intriguing information about plants, ecology, species identification, as well as tips and tricks for plant identification. Why not take a look?

How to not confuse Bear’s garlic with Lily-of-the-valley, autumn crocus, Jack-in-the-pulpit or Solomon’s seal!

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Be careful when collecting wild garlic!

March to May is bear’s garlic season once again! Many people are now on the lookout for the young leaves for herb butter, pesto or soup, but beware! There are some poisonous plants that occur at similar times in the same locations: Lily of the Valley, Autumn Crocus, Jack-in-the-pulpit and Solomon’s Seal. A safe identification is therefore essential. Please only collect plants for consumption that you have been able to identify without doubt! You can identify the leaves with Flora Incognita, but you should also know how to distinguish bear’s garlic from the other confusing species.

Bear’s garlic or lily of the valley?

You can find bear’s garlic leaves (Allium ursinum) from March to June in alluvial, deciduous and mixed forests. It is not uncommon to find the poisonous leaves of the lily of the valley (Convallaria majalis) mixed in! What is easiest is to look at how the leaves grow out of the ground: bear’s garlic seems to grow “straight out of the ground” and has a clearly recognisable stem, whereas lily of the valley usually sprouts two leaves from a rhizome – and they encompass a pseudo-stem. This means they are not as clearly divided into “stem and leaf” as bear’s garlic. Other distinguishing features are: Bear’s garlic leaves are dark green and soft, especially after picking they quickly start to collapse. Lily of the valley leaves are light green and firmer. Wild garlic has a clear midrib and parallel veins that are widely spaced. Lily of the valley does not have a distinct midrib and has very narrowly spaced nerves.

Bear’s garlic or autumn crocus?

Autumn crocus (Colchicum autumnale) sprout their leaves now – but they do not flower until autumn. Caution: Even eating the smallest amounts can lead to severe poisoning! You are more likely to find them in meadows than in the forest, and also their leaves are not clearly divided into “leaf and stem”. They grow without a stem from a rosette in the ground and also often enclose a large, green fruit capsule. Unlike bear’s garlic leaves, they are almost stiff and shiny on both sides – the underside of bear’s garlic leaves is rather dull.

Bear’s garlic or Jack-in-the-pulpit?

It is mainly the young leaves of Jack-in-the-pulpit (Arum maculatum) that can lead to confusion with bear’s garlic – because they too are now sprouting in nutrient-rich deciduous forests. Very young leaves lack the typical spots and barbs at the base of the stem, but they already show the irregular veining, which clearly distinguishes them from bear’s garlic.

Bear's garlic or Solomon's seal?

Bear’s garlic or Solomon’s seal?

Individual plants of bear’s garlic and the species of solomon’s seal (Polygonatum sp.) are probably unlikely to be confused. The risk here is rather that an individual specimen of solomon’s seal can become indistinguishable in mass occurrences of bear’s garlic and thus, in case of carelessness, be collected along with it. The parallel-veined, long-oval leaves are indeed similar to those of bear’s garlic, but they grow alternately on a stem and have a grey-green underside.

Olfactory test

Bear’s garlic is mainly recognisable by its aromatic smell, reminiscent of garlic. The confusing species don’t exactly do this, but if you have already collected and crushed a few leaves of bear’s garlic, your fingers will smell very strongly, making reliable identification by smell no longer possible.


Observe plants in the course of the year

It is only the leaves that can lead to confusion with bear’s garlic. As with other plants that are collected for consumption, we recommend that you visit their locations regularly throughout the year and look at how the individual plants flower and fruit. This way you can be sure to see, feel and smell which leaves belong to which flower: Jack-in-the-pulpit forms a characteristic “stick” of spatha and cob between April and May. Lily of the valley forms grape-like bells, almost at the same time as bear’s garlic, which forms star-shaped pure white flowers from May to June. And lastly, the autumn crocus shows its pink flowers – in autumn.

This article was displayed as a story in the Flora Incognita app in spring 2022/23. In the app you can always find exciting information about plants, ecology, species knowledge, as well as tips and tricks for plant identification. Check it out!

Early bloomers of the phenological mid spring

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Phenological season: Mid spring

The German Weather Service (Deutscher Wetterdienst – DWD) uses the flowering of forsythia and the beginning of leaf development of gooseberry as indicators for mid spring. In the next weeks, fruit trees open their flowers (cherry, pear) and beech and birch start growing their leaves. To monitor mid spring, we’d love for you to capture the following species by ID’ing them with the Flora Incognita app! Please make sure that your GPS is shared so that we can record your plants’ locations. Thank you!

Wood Anemone – Anemone nemorosa
The wood anemone often grows in large numbers in beech or mixed forests. Even if its flowers attract the first insects, the wood anemone mainly disperses vegetatively – its 30-centimetre-long, creeping rhizome lies about 1 cm below the surface of the soil. Be careful: All plant parts are poisonous!

Coltsfoot – Tussilago farfara
The coltsfoot forms a yellow inflorescence in early spring. Only after they have withered, the large kidney-shaped leaves begin to appear. While still blooming, the small brownish scaly leaves can be photographed as leaves for the app. It may not seem like a special plant, but their flowers are an important marker in terms of phenological monitoring.

Lesser Celandine – Ficaria verna
Lesser celandine or pilewort appears in early spring in various places. Some individuals show brown drawings on their leaves. The blooming period stretches over a long time, in most years until May. What we’re interested in is where and when the first flowers of lesser celandine appear, so look out for it, please!”

Blackthorn – Prunus spinosa
Blackthorn is also often called sloe. Its pure white flowers can be found on forest edges or shrubberies, where the medium-sized bush with its long thorns creates an ideal hiding space for birds. The blue berries ripen late in the year and are usually harvested after the first frost because the cold reduces the bitterness of the fruits. We‘d like to record the phenology of the blackthorn flowering stage and be happy if you contributed.

Even in cities, early bloomers get off to a fast start: warm street pavements ensure that there is already something to discover in many places! Here are a few examples:

  • Hairy bittercress (Cardamine hirsuta) – Adapted to disturbed soils, it fruits within a few weeks and then catapults its seeds up to 1.4 metres!
  • Draba verna, the spring draba, is a short-lived, few centimetres tall tiny plant among Central European flowering plants. It loves light, lean, dry sites and often mass populates pavement cracks in spring.
  • The stinking hellebore (Helleborus foetidus) is named after the unpleasant smell of its leaves. An exciting fact: yeast cultures in the nectar ensure that the temperature in the flower can be up to 6 °C above that of the surrounding area!
  • The genus speedwell (Veronica) comprises about 450 species, of which about 50 occur in Germany. The species of the genus are usually quite small, have blue flowers and many of them bloom very early in the year.
  • There are also early bloomers among the grasses. Sesleria varia is widespread throughout Germany. However, it only grows on calcareous soils such as stony, dry grasslands. It flowers from March to May.
  • Cornelian cherry (Cornus mas) blossoms in March/April, even earlier in mild areas. The flowers, rich in nectar and pollen, are the first food for honey bees and wild bees, in addition to the willow. In autumn, their fruits are very popular with songbirds.

Winter aconites in the Rautal valley near Jena

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The Rautal – yellow wonderland
The Rautal valley near Jena is known far beyond the borders of Thuringia for its unique mass occurrence of the winter aconite in Central Europe. The yellow carpet of blossoms spreads over almost five hectares and grows larger every year. As soon as the first strong rays of sunshine warm the ground and the days become longer again, the small flowers germinate and cover the otherwise still bare forest floor with their intense shade of yellow. The winter aconite was probably brought to the Rautal as a root bulb together with vines from Southern Europe. It was first mentioned there in 1803.

Accompanying heralds of spring
The hardwood forest, which is home to the mass occurrence of the winter aconite, has been a protected landscape since 1965 and covers an area of 4.3 hectares. In addition to the winter aconites, more than 120 different vascular plants occur in this area, signifying a high species richness for a forest. Among the estimated 1.6 million winter aconites, there are also individual occurrences of liverworts, lungworts or mullein in spring.

Explore the trail of winter aconites
To see the “yellow wonder”, many people make their way to the Rautal valley on sunny spring weekends. For this reason, a hiking trail leading to the winter aconite has been established. It leads through mainly beech forest, past outcrops of rock and, with only a slight incline, leads to the best views of the sea of yellow. However, good footwear is recommended as the path can often be muddy. The trail starts at the road between Jena and the village of Closewitz and can be extended as far as desired through the adjacent “Windknollen” nature reserve.

Documenting plant diversity with Flora Incognita
Did you know? The flowering of the winter aconite is a good indicator for monitoring the phenological seasons throughout Germany. If you have shared your location with Flora Incognita and identify a winter aconite (or other early bloomers), you are making an important contribution to the preservation of plant diversity!

This article was displayed as a story in the Flora Incognita app in winter 2022/23. In the app you can always find exciting information about plants, ecology, species knowledge, as well as tips and tricks for plant identification. Check it out!

 

What is the earliest flower to bloom?

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The phenological early spring officially begins with the flowering of hazel and snowdrops. Exactly when the first species begin to flower varies greatly over the years, and it also depends on the location. High up in the mountains it is far colder than in the lowlands. There have been observations as early as December, but in some places as late as mid-February. In any case, the use of Flora Incognita is recommended right from the start of flowering: with every plant identification you contribute to the monitoring of biodiversity! (But only if you have shared your location) – So it is worthwhile to continue photographing early bloomers every year, even if you already know the species. Read more

How do plants survive the winter?

How do plants survive the winter?

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Plant cells consist largely of water – if this freezes, it expands. This would damage the cells and, in the worst case, kill the plant. So how do plants protect themselves from freezing to death?

Botanical winter dormancy
The falling leaves of the pedunculate oak, the late-ripening apple and the falling needles of the European larch mark the beginning of the phenological winter. There are warmer days in the Central European climate even in winter, but the plants native here still remain in winter dormancy. The reason for this is the breakdown of certain phytohormones (e.g. abscisic acid), which regulate when seeds and buds (re)sprout after the cold period.

 

Hibernation as seeds
Annual herbaceous plants die in autumn and only ensure their survival through seeds. These consist of a seed coat, a nutritive tissue and the embryo. Humans use plant seeds as a valuable part of their diet – beans, peas and lentils are rich in protein; wheat and oats provide starch. Some seeds, on the other hand, are high in fat, such as oilseed rape, flax or pumpkin. Their hard shell and low water content protect them from freezing. The duration of dormancy varies greatly among individual plant species, as do the factors that lead to its breakdown. Possible influencing factors are: Humidity, temperature, light conditions and the nutrient content of the soil.

 

Above-ground withering
Perennials are herbaceous, perennial plants that can survive many winters. Their survival strategy is to store energy-rich nutrients (mostly starch) in roots, bulbs, tubers or the rhizome. New buds and shoots develop from the so-called meristem – a tissue consisting of undifferentiated cells that continuously divide and thus release new cells into the plant body. In winter, these tissue parts often rest as „sleeping eyes“ (botanically: provenance bud) just below the soil surface.

 

Retreating back into the wood
When deciduous trees show their typical autumn colours, this is a sign that no more new chlorophyll is being produced in the leaves – the constant process of decay is now visibly taking place. Over several days to weeks, the chlorophyll is transferred to the trunk along with other energy-rich particles. The vacuoles therein divide themselves and become enriched with sugar, but also with proteins and other dissolved substances such as potassium, magnesium and phosphorus. Other cell parts – the amyloplasts, become starch reservoirs, which are eventually used up by the time the leaves emerge.

 

Natural antifreeze
Evergreen plants do not die above ground and keep their leaves. Ice-covered blades of grass don’t break if you step on them – what strategy protects them from freezing? Water freezes at 0° – but not necessarily! Seawater remains liquid because salt, as an osmotically active substance, lowers the freezing point. In plant cells, various sugars, alcohol compounds and also potassium are found as effective antifreeze agents. The more of these molecules are dissolved in the cell water, the stronger the effect of lowering the freezing point.

 

Cold protection through growth forms
The growth form of the plant also plays a role in frost protection: especially in the high mountains, one encounters dense plant cushions in which the branches stand very closely together. This protects the inner leaves and buds like a blanket from the damaging effects of frost. Plants have found many ways to defy the icy months. But it is also exciting to look further afield! Some plant survival strategies are useful on completely different levels: A study from England for example, found that a dense growth of ivy (Hedera helix) can significantly reduce the number, duration and severity of frost damage to historic walls!

This article was displayed as a story in the Flora Incognita app in winter 2022/23. In the app you can always find exciting information about plants, ecology, species knowledge, as well as tips and tricks for plant identification. Check it out!