Friday, 9 August 2024

Goldenrod – nawłoć – friend or foe?

A casual chat with my colleague Ilona from our Wrocław office led me down this rabbit hole – is the plant I have growing all around my house on my działka good for the environment or bad?

Ilona told me that nawłoć (goldenrod) was an aggressively invasive weed that is threatening biodiversity. I had hitherto understood that this plant, with its bright-yellow flowers, was a native to Mazowsze, as evidenced by the name of the street linking ulica Trombity and ul. Karczunkowska in Jeziorki – ul. Nawłocka. For indeed, nawłoć grows all along the side without houses on it. Maps of Warsaw going back to the 1970s show the street named thus.

This exchange prompts my curiosity. In my youth, a trip to a library to find some books on botany would have been in order; today, all such reference is just a few keyboard taps away. And so I find...

In English: "Goldenrod is a common name for many species of flowering plants in the sunflower family, Asteraceae, commonly in reference to the genus Solidago." And in Polish? Nawłoć (Solidago) – „rodzaj roślin z rodziny astrowatych. Należy do niego ponad 130 gatunków."

OK, the key question is – which species of goldenrod are we talking about? 

Comparing pictures of the flowering plant with the one I have in front of me as I look out from my kitchen window, it turns out that Ilona is right – the nawłoć that's taken over my lawns is indeed of the Canadian variety (Solidago canadiensis, or nawłoć kanadyjska). Is this a good thing or a bad thing? No apologies for copy-pasting a chunk of the Wikipedia article about S. canadiensis...

Ecology and distribution

S. canadiensis is sometimes browsed by deer and is good to fair as food for domestic livestock such as cattle or horses. It is found in a variety of habitats. It typically is one of the first plants to colonise an area after a disturbance (such as fire) and rarely persists once shrubs and trees become established. It is found in dry locations and waterlogged ones.

Canada goldenrod is visited by a wide variety of insects for its pollen and nectar, including bees, wasps, flies, beetles, butterflies, and moths. It is especially strongly favored as a nectar source by bumblebees and wasps, it is also visited frequently by honeybees and some butterflies.

S. canadiensis can be extremely aggressive and tends to form monocultures and near-monocultures. It not only seeds a great deal, but also spreads rapidly via running rhizomes. Its root system is very tough, and plants that have been pulled out of the ground prior to freezing and left exposed atop soil have survived winter temperatures down to -26 °C.

Looking at my działka, I can see that the goldenrod is very attractive to the pollinators. It has effectively replaced the two lawns at the front of my house. Below: one of many bees on one of many goldenrods by my house. Look at how much pollen it has gathered on its legs. I'm not a bee psychologist, but this looks like a happy one.

As well as attracting bees and butterflies, it is also massively out-produces oxygen compared to lawn grass (even if not mown), due to a larger leaf area. Another advantage of S. canadiensis, according to ChatGPT, is that its flowers bloom late in the season, offering a crucial food source when other plants have finished flowering. Google Gemini adds that goldenrod is a "deep-rooted plant that helps improve soil structure, prevent erosion, and increase organic matter content".

It has spread widely across southern Mazowsze; it worries me not.

Overall, I'm happy to have had parts of my działka overrun by Canadian goldenrod. It doesn't compete with my fruit trees ("rarely persists once shrubs and trees become established"). It brings a welcome splash of bright yellow in August and September.

This time last year:
A low-cost future

This time two years ago:
Evolved Consciousness

This time four years ago:
Goodnight Belarus - may God keep you

This time nine years ago:
Motorbike across Poland to buy fine Polish wine

This time ten years ago:
Eat Polish apples, drink Polish cider

This time 11 years ago:
Hottest week ever 

This time 12 years ago:
Progress along the second line of the Warsaw Metro 

This time 13 years ago:
Doric arches, ul. Targowa

This time 14 years ago:
A place in the country, everyone's ideal

This time 17 years ago:
I must go down to the sea again

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