Phenology: Early Autumn – Warm Days, Cool Nights

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?

Ilmenau Science Night and Max Planck Day 2023

Ilmenau on the evening of July 1, 2023. People glance at their mobile phones to check if they’ll need an umbrella due to the weather. But is that all? No!

Some of them look at their phones to read about a pink-blooming wild plant: Epilobium angustifolium, it says, the Narrow-leaved Willowherb. Belongs to the Evening Primrose family and grows at the forest edge. Or Hypericum perforatum, the Common St. John’s Wort. “I know that as tea! So that’s how it looks?” Yes!

These situations and many similar ones were experienced as, on July 1, 2023, the doors of (among others) the Zuse Building at TU Ilmenau opened for Ilmenau Science Night, and many interested people came by to “personally meet Flora Incognita.” And we were well-prepared: With blooming wild plants in pots, an app quiz, and botanical tours around the university campus, but also with advanced offerings like microscopic examination of phytoplankton or information stands that explained how the Artificial Intelligence behind Flora Incognita is already being used to identify field wildflowers through drone images, or to support urban planners in creating bee-friendly landscapes.

Another focus of our presentation was to educate about how we conduct research with the plant identifications from the Flora Incognita app. Our scientists were eager to point out that the data already allows for the detection of phenological shifts in plant flowering phases, or that the spread of invasive species like Impatiens glandulifera can be monitored. In light of ongoing climate change, such information is very valuable; and with Flora Incognita’s new project feature, it’s easy for nature enthusiasts to conduct their own citizen science projects and analyze the observation data collected.

It’s always something special to engage with long-time fans and learn which aspects of the app are particularly popular and which ones have room for improvement. But we’re equally proud when we can dispel skepticism and encourage people to simply try out the app and start identifying plants. Fun Fact: Secretly, we like to count how many new installations we can achieve through our on-site efforts at such events!

But it’s not just in Ilmenau where we could convince: Also in Göttingen, where on June 23, in honor of the 75th anniversary of the Max Planck Society, Max Planck Day took place, we were present with an information booth on the marketplace. Unfortunately, due to persistent rain, not many people were out and about, but that allowed us to engage in longer and more intense conversations with interested individuals about our app, the loss of biodiversity, and our research work. In Göttingen, we were joined by scientists from the ATTO Tower (MPI for Biogeochemistry Jena and MPI for Chemistry Mainz), who invited attendees to climb the measurement tower in the Amazon rainforest and talk about their climate research using a VR station. A special highlight of the day was the visit of Prof. Patrick Cramer, the new president of the Max Planck Society, to our booth.

At this point, we would like to extend a heartfelt thank you to everyone who took the time to convey praise and criticism, ask questions, and be curious. Thanks also to Manuel Maidorn and the staff of the Max Planck Institute for Dynamics and Self-Organization in Göttingen for providing the many plants at the booth! Our gratitude also goes to our sponsors who make this public outreach possible.

See you soon!

collage of pictures taken at both events. They show our team on site, visitors on the booths, and plant identification with the Flora Incognita app.

Title image: Max Planck Society, photograph by David Ausserhofer

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

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

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!

Plants Alongside and Inside Rivers

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).


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?