A closer look at flowers: thermoregulation in winter

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In winter or in cold habitats such as high mountains, an optimal flower temperature is important for successful reproduction. Some plants can actively produce heat in their flowers, such as Helleborus foetidus, using yeast bacteria in the nectar (Herrera and Pozo, 2010). But this is the exception. For most plants in cold regions (or early bloomers), the more heat they can absorb from the environment, or at least not lose, the better. In this story you will learn what influence characteristics such as shape, colour, pubescence or orientation to the sun have on the temperature in the flower.

Bells and discs
Have you ever wondered why many early bloomers have bell-shaped flowers? The answer is that bells collect more heat than disc-shaped flowers. Hanging bells can absorb heat from the ground radiation and so the temperature inside the flower lies 3-11 °C above the ambient temperature (Kevan, 1989). Upright bells, such as gentians, bundle the sun’s rays when they fall at a certain angle. In disc-shaped flowers, the reproductive organs are directly exposed to the environment and are located in the centre, where most of the incoming light is reflected by the flower. But the petals also play a role. In one experiment, the excess temperature in Saxifraga oppositifolia flowers was reduced by 70% compared to the surrounding area after removing the petals (Kevan, 1970).

Micro-greenhouses
Another successful strategy is the formation of “micro-greenhouses”. These are, for example, bubble-shaped structures made of translucent bracts, as in the yellow rattle (Rhinanthus minor), or sepals, as in Physalis. These filter light in the UV range, but allow longer wavelengths to pass through, which heats the air inside. Similar to flowers, hollow stems can also have a heating effect if the heat trapped in the stem leads to an increase in internal temperature (Kevan et al. 2018, 2019). This can promote the development of the flower bud immediately above it.

Orientation towards the sun (heliotropism)
During the course of the day, some plants permanently orientate their flowers so that they face the sun. In cold regions in particular, this leads to effective warming of the flower. This can have advantages for the plant, for example through increased temperatures in the reproductive organs, heavier seeds and more visits from pollinators. Many experiments have already tried to demonstrate the added value of heliotropism, but not always successfully. (Van der Kooi, 2019).

Colour
Darker colours can absorb more solar radiation. This can be converted into heat, which can increase the temperature of the flower. In a series of experiments with Plantago, a close relationship was found between the colour of the flower-bearing inflorescence and its temperature. Individuals developing at low temperatures produced darker panicles that were 0.2-2.6 °C warmer in direct sunlight than the comparison group (Anderson et al., 2013). Another study found that purple-coloured flowers of Ranunculus glacialis were warmer and produced more seeds than white-coloured flowers of the same species (Ida & Totland, 2014). However, there are also studies in which the colour of the flower has no influence on the flower temperature (Van der Kooi, 2019). Further studies are needed to better understand the relationship between flower colour, temperature and reproductive capacity.

Opening and closing
The opening and closing of flowers through petal movement is widespread throughout the plant world. In particular, cup- or disc-shaped flowering species protect themselves from external factors such as light, moisture or temperature in this way. Opening and closing can take several minutes or hours, depending on the species. It is assumed that closing the flower protects the pollen from precipitation (washing out, damage) or drying out, which increases its viability. There are various experiments that have investigated the influence of flower closure on the temperature inside the flower: For example, if the bracts of Tulipa iliensis close at cool temperatures, a more constant temperature is maintained inside the flower (Abdusalam and Tan, 2014).

Hairs
The pubescence of flowers is probably important for maintaining flower temperature, but in contrast to leaf pubescence, this has been little studied to date. Plant species that grow in high-altitude, cold regions sometimes develop thick leaf pubescence. This creates an insulating boundary layer to the neighbouring cold air mass, which reduces heat loss (Meinzer and Goldstein, 1985). The pubescence of the flowers can have a similar insulating effect as in the example of willow catkins: In Alaska, it was investigated that it can be 15-25 °C inside willow catkins at an air temperature of 0 °C. If the woolly hairs were removed, the internal temperatures in the catkins fell by around 60% (Krog, 1955).

References:
• Herrera CM, Pozo MI. 2010. Nectar yeasts warm the flowers of a winter-blooming plant. Proceedings of the Royal Society of London B 277: 1827–1834.
• Kevan PG. 1989. Thermoregulation in arctic insects and flowers: adaptation and co-adaptation in behaviour, anatomy, and physiology. Thermal Physiology 1: 747–753.
• Kevan PG, Nunes-Silva P, Sudarsan R. 2018. Short communication: thermal regimes in hollow stems of herbaceous plants—concepts and models. International Journal of Biometeorology 62: 2057–2062.
• Kevan PG, Tikhmenev EA, Nunes-Silva P. 2019. Temperatures within flowers and stems: possible roles in plant reproduction in the north. Bulletin of the NorthEastern Science Centre of the Russian Academy of Sciences, Magadan, Russia 1: 38–47.
• Casper J van der Kooi, Peter G Kevan, Matthew H Koski, The thermal ecology of flowers, Annals of Botany, Volume 124, Issue 3, 16 August 2019, Pages 343–353,
• Anderson ER, Lovin ME, Richter SJ, Lacey EP. 2013. Multiple Plantago species (Plantaginaceae) modify floral reflectance and color in response to thermal change. American Journal of Botany 100: 2485–2493.
• Ida TY, Totland Ø. 2014. Heating effect by perianth retention on developing achenes and implications for seed production in the alpine herb Ranunculus glacialis. Alpine Botany 124: 37–47.
• Abdusalam A, Tan D-Y. 2014. Contribution of temporal floral closure to reproductive success of the spring-flowering Tulipa iliensis. Journal of Systematics and Evolution 52: 186–194.
• Meinzer F, Goldstein G. 1985. Some consequences of leaf pubescence in the Andean giant rosette plant Espeletia timotensis. Ecology 66: 512–520.
• Krog J. 1955. Notes on temperature measurements indicative of special organization in arctic and subarctic plants for utilization of radiated heat from the sun. Physiologia Plantarum 8: 836–839.
• Kevan PG. 1970. High arctic insect-flower relations: the inter-relationships of arthropods and flowers at Lake Hazen, Ellesmere Island, N.W.T., Canada. PhD Thesis, University of Alberta, Canada.

This article was featured as a story in the Flora-Incognita app in winter 2024. In this plant identification app, you can find exciting information about plants, ecology, and species knowledge, as well as tips and tricks for plant identification. Check it out!

Winter jasmine or forsythia?

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“So early this year!”
Every year from Christmas onwards, we receive messages that the “forsythia is blooming particularly early this year”. No wonder, as its yellow flowers shine particularly beautifully in the gray dreariness (of our towns and villages) – but beware! The shrubs often catching the eye in December and January are (usually) not Forsythia (Forsythia × intermedia). They are often winter jasmine (Jasminum nudiflorum). Let’s take a closer look at the differences:

Winter jasmine
It originates from China and was brought to Europe as an ornamental plant. In France, it is already considered to be permanently wild. If its drooping branches touch the ground, they take root – which leads to the shrub growing tangled and dense.
Winter jasmine blooms from the end of December, and frosty days don’t bother the plant much – it constantly produces new flowers on its light green, bare shoots. Hence, the species name: nudiflorum means “naked-flowered”. A closer look at the flower shows that five to six yellow petals have grown together to form a corolla. Unlike many other jasmines, its flowers are not fragrant.

Forsythia
Forsythia hybrids are popular and rich in flowers (but still bare in January, as can be seen in the picture above). They form upright shrubs of up to 3 m in height. In the 1950s, forsythias were starting to flower in April, but due to climate change, the onset of flowering is shifting further and further into March, occasionally as early as February. Their flowers grow tube-shaped, with four zip-shaped, short, fused petals on bare, brown shoots. In addition to the highly cultivated ornamental plants (hybrids) from China, Korea, and Japan, there are several natural species, including one that is native to the Balkan Peninsula in Europe. It flowers in April and is rarely cultivated as an ornamental plant outside botanical collections.

Summary
Winter jasmine flowers from Christmas until around March, when forsythia also begins to flower. Winter jasmine forms tangled, drooping shrubs, while forsythia grows upright. The shoots of winter jasmine are green, and forsythia shoots are brown. The 5-6 petals of winter jasmine are roundish and fused together to a corolla, while forsythia has 4 petals fused together in a tube shape.

 

This article was featured as a story in the Flora-Incognita app in winter 2023/24. In this plant identification app, you can find exciting information about plants, ecology, and species knowledge, as well as tips and tricks for plant identification. Check it out!

Autumn Leaves: What Lies Behind the Explosion of Colors and Rustling Leaves?

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Magical Autumn
Green, yellow, red, brown leaves in all transitional phases currently call for long forest walks, providing atmospheric nature experiences and creative inspirations. However, there’s nothing magical behind this: decomposition and substance transport are responsible for the transformation. The aging process is known as senescence, and the eventual leaf fall is termed abscission. Let’s take a closer look at both:

Senescence – the Last Chapter of Phenology in the Year

Genetically controlled and dependent on available energy, leaves age in autumn. They take in less and less CO2 and eventually cease photosynthesis altogether. When the leaves fall to the ground, this is measurable through remote sensing. The so-called “browning,” the brownish appearance of the ground beneath the bare tree, marks the end of the phenological year. But why do deciduous trees shed their leaves?

Leaf Shedding – Threefold Genius

Leaves evaporate large amounts of water, around 300 to 600 liters per square meter of leaf area per year in a beech tree, for example. Roots absorb the necessary water from the soil, which is not possible when it’s frozen. The tree would dry out. By shedding leaves, this flow of water is stopped, and the tree survives the winter unscathed. But there are two more important advantages that come with leaf fall: the environmental toxins accumulated and stored in the leaves are disposed of, and bare trees withstand snow loads better.

The Chemistry of Autumn Colors

The vibrant colors of the autumn forest are present in the leaves throughout the year but masked by green chlorophyll! When chloroplasts, the storage sites of chlorophyll, are transformed into gerontoplasts within cells, chlorophyll breaks down, revealing other pigments. Carotenoids appear yellow-orange, and anthocyanins bring out red tones – incidentally, as a stress response to excessive sunlight. The red pigments act as a shield against intense sunlight and ensure that chlorophyll breakdown occurs in dying leaves even on cold, sunny autumn days.

How Does Leaf Fall Work?

When exactly a leaf falls from a branch depends on various factors. There is a genetic component for each species, but also site characteristics such as altitude, temperature, day length, and wind play a role. Decreasing availability of light and warmth activates phytohormones, and at the end of the leaf stalk, an anatomical process of change occurs: a separation tissue forms where middle lamellae, cell walls, or entire cells dissolve. Eventually, the leaf’s own weight is enough for it to fall to the ground.

This article was featured as a story in the Flora-Incognita app in autumn 2023. In the app, you can find exciting information about plants, ecology, species knowledge, as well as tips and tricks for plant identification. Why not take a look!

Phenology: Late Autumn – Preparing for Winter

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Leaf surfaces play a crucial role in plant biology, facilitating the evaporation of water absorbed through roots. The shedding of leaves in autumn prevents them from drying out when frost freezes the water in the soil. Late autumn marks the final phenological season before the period of dormancy, signaled by the changing color of English oak leaves and the shedding of leaves in many other deciduous trees.

Leaf Coloring in English Oak

English oaks (Quercus robur) are found from the North German Lowlands to altitudes exceeding 1000 meters in the Alps. Their habitat extends far beyond Central Europe, reaching into the Caucasus region. As chlorophyll is broken down, revealing other plant compounds (carotenoids impart yellow hues, anthocyanins create red tones, and water-soluble pigments produce brown shades after leaf death), autumnal oak leaves glow in yellow and brown hues.

Rowan Leaf Fall

According to the German Weather Service, the rowan tree (Sorbus aucuparia) shedding its leaves is a key indicator of late autumn. Rowan leaves are alternately arranged on branches and are distinct with leaf stalks and leaf blades. Their vibrant red autumn coloring makes them a popular sight. The tree’s fruits, known as rowan berries, often remain on the tree in clusters throughout winter, providing essential food for songbirds during winter.

A Touch of Green

Late autumn is also marked by the appearance of tender green fields, signifying the emergence of winter crops. Winter wheat, sown in mid-September, germinates within 15-20 days, displaying the first green shoots. However, the elongation growth and leaf development occur in spring.

This article was featured as a story in the Flora-Incognita app in autumn 2023. The app provides fascinating information about plants, ecology, species identification, as well as tips and tricks for plant identification. Feel free to explore!

The Autumn Crocus

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The article discusses the autumn crocus, also known as Colchicum autumnale, which belongs to the Colchicaceae family. There are about 100 species in this family, and the autumn crocus is the most well-known member. It blooms with light-violet flowers in late summer to autumn, adding a last touch of color to our meadows. Despite their name, they are often mistaken for crocuses (Crocus sp.), which belong to a different plant family, the iris family (Iridaceae).

The autumn crocus is a herbaceous and highly poisonous plant. It produces one to five flowers from its corm (a type of bulb-like storage organ). The flowers are generally larger, around 20 cm in length, compared to crocuses. One way to distinguish them is by counting the stamens: the autumn crocus has six stamens, while a crocus has only three.

Unlike crocuses, autumn crocuses produce leaves separately from their flowers. These leaves appear in early summer, always without flowers. However, there’s a potential danger of confusion with another plant, wild garlic (Allium ursinum), which is often collected and consumed. To avoid mistaking wild garlic for other plants like autumn crocuses, you can follow specific guidelines to differentiate them. Here’s an article that guides you through on how to differentiate wild garlic, Lily-of-the-valley, autumn crocus, Jack-in-the-pulpit or Solomon’s seal!

 

The article was displayed as a story in the Flora-Incognita app in autumn 2023, providing users with interesting information about plants, ecology, species identification, as well as tips and tricks for plant identification.

Phenology: Full Autumn

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A glance into nature reveals ripe dogwood cherries lying on the ground, and autumn crocuses have faded away. A new phenological season begins: Full Autumn. Perhaps it will bring us a “Golden October” with many warm days, but weather is not an indicator of phenology. Phenology observes the annual developmental cycle of plants, and thus, Full Autumn is defined by the fruit ripening of the pedunculate oak, followed by late pear varieties and grapevines. The highlight is the foliage coloration of the horse chestnut. Full Autumn comes to an end when the leaves of the European beech and pedunculate oak change color and begin to fall. On average, Full Autumn lasts from September 17th to October 19th.

Acorns

The pedunculate oak (Quercus robur) belongs to the beech family. It is widespread in Europe and tolerates both (short) waterlogging and dry periods. Consequently, it is found both in lowlands and at elevations of up to 100 meters above sea level. In April-May, the pedunculate oak blooms, and by then, its namesake feature becomes apparent: the flowers (and later the acorns) are borne on 4-6 cm long stalks. Acorns are an important food source for many bird and mammal species (jaybirds, squirrels).

Late Pear Varieties

Comparing apples and pears is rarely a good idea, but one thing can be said: pears (Pyrus communis) need more warmth than apples to unleash their full flavor. Early pear varieties must be consumed quickly and are not suitable for storage. The fruits ripening in autumn can be stored – depending on the variety – well into winter. Classic aromatic pear varieties include Conférence and Gellerts Butterbirne. Among the novelties, the productive variety “David” stands out with firm, sweet, juicy fruits, ripening from early to mid-October.

Grapes

The grapevine (Vitis vinifera) is the Medicinal Plant of the Year 2023 because its fruits (grapes) are rich in secondary plant compounds. These are mainly concentrated in the seeds of the berries. However, they can also be found in the skin and leaves of red grapes. To determine if a grape is ready for harvest, check if all its berries are colored, the fruit stalks are woody, and the seeds inside the berries are brown, not cream-colored, and easily separate from the surrounding pulp. Grapes are best cut off completely from the vine with scissors and can be stored in the refrigerator for up to 14 days – provided spoiled berries are removed beforehand.

Horse Chestnut

There are several species within the horse chestnut genus, but phenologically interesting is the common horse chestnut (Aesculus hippocastanum). By the way, the sweet chestnut, Castanea sativa, from which delicious chestnuts come, is not related to horse chestnuts! The horse chestnut originates from the mountainous regions of the Balkans and has been widely planted as a street tree in Central Europe since the 16th century. White-flowering horse chestnuts often suffer from infestation by the horse chestnut leaf miner. This leads to premature wilting and dropping of leaves in August to early September. If you want to document the foliage coloration of the horse chestnut as an indicator for phenology, please use healthy trees.

This article was displayed in the Flora-Incognita app as a story in autumn 2023. In the app, you can find exciting information about plants, ecology, species knowledge, as well as tips and tricks for plant identification. Why not take a look!

The Medicinal Plant of the Year 2023: The Grapevine

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Sun-Loving Climbing Plant

In viticulture, several hundred grapevine varieties are cultivated. They all belong to Vitis vinifera, the grapevine. There are eight to ten thousand varieties of it, and what they all have in common is their tendency to seek support with tendrils and extend their roots deep into the soil to draw water from great depths. This adaptation makes them drought-resistant and sun-loving. With proper care, grapevines can live up to 100 years.

Health-Promoting Compounds

The fruits (grapes) are rich in secondary plant compounds, such as oligomeric proanthocyanidins (OPC). These compounds are primarily concentrated in the cores of the berries, which should be considered when buying seedless grapes from the market. However, they are also found in the skin and leaves of red grapes. These substances primarily serve the plants by protecting them from UV radiation and parasites. In the human body, they exhibit antioxidative and anti-inflammatory properties, and it has been demonstrated that OPC can inhibit the growth of colon cancer cells in certain doses. For more information on this topic, it is best to consult your trusted doctor.

But it’s not just the fruits that are significant: the plant sap that emerges in spring (referred to as grapevine sap) is a popular ingredient in cosmetics, and grape leaves also play a role in many (medicinal) kitchens. Red grape leaves support venous disorders, and grape leaves pickled in early summer are a vegetable rich in fiber, protein, as well as Vitamin E and K, folic acid, and minerals.

A New Badge for You!

If you find and identify a grapevine this year, you will receive a new badge for your profile: the Medicinal Plant of the Year 2023!

This article was featured as a story in the Flora-Incognita app in autumn 2023. In the app, you can find exciting information about plants, ecology, species knowledge, as well as tips and tricks for plant identification. Why not take a look!

Phenology: Early Autumn – Warm Days, Cool Nights

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The dog days are over, marking the end of the warmest time of the year. Now, we find ourselves at the beginning of a new phenological season: early autumn. Phenological seasons are characterized by specific developmental stages of certain indicator plants, including flowering, leaf unfolding, fruit ripening, autumn leaf coloration, and leaf fall. The early autumn, which is beginning now, is characterized by the fruit ripening of elderberries and cornelian cherries. Let’s take a closer look and explore the other events that await us in the next (approximately) four weeks.

Ripening Elderberries

The elderberry (Sambucus nigra) is one of the most common shrubs in Central Europe. Botanically, the “berries” are classified as drupes. They are rich in vitamin C and potassium, and are edible after cooking. However, when consumed raw, some people may experience nausea or vomiting due to the presence of plant toxins. In herbal medicine, their juice is considered a remedy for colds, kidney and bladder problems, and for strengthening the heart and circulation. They are also used in cooking: in elderberry soup with semolina dumplings or rusks, as jelly, juice, or fruit wine – the possibilities are numerous.

Vibrant Red Cornelian Cherries

Is it a large shrub or a small tree? Both forms can be found in cornelian cherry (Cornus mas) specimens. Mature specimens can grow up to 8 meters tall with a trunk diameter of 45 cm. Its glossy red fruits, about 2 cm long, are classified as drupes and have a similarly red, sour flesh. This flesh contains 70–125 mg of vitamin C per 100 g. The fruits can be eaten raw, dried, frozen, or processed into liqueur, wine, juice, jelly, and jam.

Autumn Crocus Blooms

Autumn crocus (Colchicum autumnale) is a herbaceous, highly poisonous plant. One to five flowers sprout from its bulb. It can be found in moist meadows or open floodplain forests. The crocus-like flowers emerge without leaves – the leaves grow in spring and are quite similar to wild garlic. The pale pink to violet flowers, about 20 cm long, are significantly larger than regular crocuses (some of which also bloom in autumn). To distinguish them, count the stamens. Autumn crocus has six, while regular crocuses have three.

Sunflowers ready for harvest

By the end of August, sunflowers (Helianthus annuus) are ripe – provided they receive enough sun and water during their 150-day growth period. You can tell they are ready for harvest by the browning of the seeds in the center of the flower head and the ease with which they detach. The back of the flower head also turns brownish-black. It’s best to cut the entire flower head and then shake out the seeds – in stubborn cases, a small brush can help access the seeds. Stored washed and dry, you can peel and roast them for snacking, or leave them raw to provide wild animals with food during the cold season.

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

The Tree of the Year 2023: The Bog Birch (or Downy Birch)

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Birches in Central Europe
In Central Europe, there are four native species of birch. Three of them prefer moorland habitats: the dwarf birch (Betula nana), the shrub birch (Betula humilis), and the bog birch (Betula pubescens), also known as downy birch. The fourth species, the silver birch (Betula pendula), in contrast to its sisters, is particularly drought-resistant and thus widespread in other locations. In 2023, the bog birch was chosen as the Tree of the Year. But why?

Bog Birch
The bog birch is a pioneer that can quickly colonize treeless, raw soils. It prefers cold and marshy locations, as well as plenty of light. Under the shelter of its sparse leaf canopy, future tree species in the forest can grow, and due to its short life span, it gives way to established species after about 100 years. However, in high moors, at the tree line in the Alps, or on talus slopes in the mountains, one can find bog birches that permanently populate these sites, not just as initial colonizers. These habitats are characterized by a vast biodiversity, hosting beetle, cicada, bug, wasp, and butterfly species specialized in bog birches and bog birch forests. Additionally, various birch fungi and mushroom species symbiotically associate with bog birches.

Tree of the Year
Every year in Germany, the “Tree of the Year – Dr. Silvius Wodarz Foundation” designates a specific tree species as the “Tree of the Year.” This proclamation aims to generate a particular interest in the selected tree species, trees in general, and the concerns of nature and environmental protection. The bog birch was chosen as the Tree of the Year to raise awareness about the decline of bogs. Over 90 percent of the original bog areas in Germany have already been drained, mainly to gain agricultural land. Original bog birch forests are therefore considered highly endangered and are now legally protected nationwide.

A New Badge for You!

If you identify a bog birch using the Flora Incognita app this year, you will be rewarded with the “Tree of the Year 2023” badge!

This article was featured as a story in the Flora-Incognita app in autumn 2023. The app provides fascinating information about plants, ecology, species identification, as well as tips and tricks for plant identification. Feel free to explore!

Phenology: Late Summer – Harvest Season Begins

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Every year, a clear chronological sequence of events such as the beginning of flowering, fruit ripening, or leaf coloring of specific plant species repeats itself. Thoroughly documented, phenology provides important data on the changes in regional climate – benefiting, for example, farmers who can adjust their tasks like sowing and harvesting according to the corresponding developments in plant life. Moreover, large-scale climatic changes can also be mapped using phenological data. Plant identifications with Flora Incognita assist in documenting phenology worldwide. Thank you for your contribution! The phenological late summer in Germany typically lasts only about 18 days. The official indicator of this season is the picking ripeness of early apple varieties, but there is much more to discover!

Early Apples are Ready to Pick

The White Transparent apple (Malus domestica), originating from Latvia, has been widespread in Europe since the end of the 19th century. This old variety is known for its early ripening from late July and its short shelf life: the fruits become mealy and spoil after about 2 weeks. For professional cultivation, the variety is no longer relevant, but it can still be found in many gardens. We are sure: many apple pies will be baked this year from the first White Transparent apples of the season. Other early apple varieties include James Grieve, Julka, Paradis Katka, Piros, and Retina.

Ripening of Serviceberries

The Serviceberry or Juneberry (Amelanchier lamarckii), native to the USA, is popular in Europe as an ornamental shrub due to its spring blossoms and magnificent autumn colors. Its almost black and sweet fruits ripen in late July and can be dried and used like currants. Unlike true currants, which are dried berries of the Corinth grape variety (Black Corinth), Juneberries belong botanically to the rose family. The Common Juneberry (Amelanchier ovalis), which is native to Germany, also ripens in July. Many birds love the small, dark fruits, but they are also a great choice for making jam or liqueur.

Rowanberries are Ripe

Rowanberries are the fruits of the mountain ash tree (Sorbus aucuparia). They ripen from August into early autumn. Botanically, they belong to the pome fruit family – if you examine a fruit closely, you will see that it looks like a tiny apple! Rowanberries often hang in clusters on the tree throughout winter and are an important food source for songbirds during this time. Did you know? Overripe fruits can develop significant alcohol content through the anaerobic fermentation of sugar components! For example, starlings or waxwings can easily tolerate a blood alcohol level equivalent to 0.3‰. Both their digestive tract and metabolism are adapted to this effect.

Heather is in Bloom

Late summer is also the time when heather (Calluna vulgaris) begins to bloom. This evergreen dwarf shrub can live up to 40 years and grow up to one meter tall – provided its growth is undisturbed. The white to purple, 1-4 mm long flowers form in clustered inflorescences and provide ample nectar for many wild bees, butterflies, and honeybees. Fans of heather honey appreciate its bitter aroma and jelly-like consistency. In many flower boxes, cultivated varieties of heather can be found in a variety of colors, including variants that maintain these colors for weeks. Please note, these are so-called bud bloomers, whose flowers never open – they are inaccessible to bees and other insects!

 

This article was featured as a story in the Flora-Incognita app in autumn 2023. The app provides fascinating information about plants, ecology, species identification, as well as tips and tricks for plant identification. Feel free to explore!