Municipal agents and building owners hunt them down relentlessly. The wild weeds that grow along the sidewalks or in the cracks in the walls are, however, reservoirs of biodiversity. To better understand the functioning of urban ecosystems, the National Museum of Natural History and the Tela Botanica association launched “Sauvages de ma rue” ten years ago.
This participatory science program invites the general public to identify urban plants. This involves choosing a street and listing all the species visible on a field sheet, to be sent to the observatory site (1). When a participant cannot identify a plant, all they have to do is take a picture of it and the entire network (57,000 botanical enthusiasts!) comes to their aid, via the Identiplante platform.
The virtues of “spontaneous flora”
A paper guide (2) also lists, by color and shape, the 240 most common species. “Over time, our eye becomes hardened and our gaze changes on this spontaneous flora whose diversity and virtues we discover, such as the big mallow, used for centuries as a remedy against coughs, or the plantain, effective against mosquito bites »lists Élodie Masseguin, coordinator of participatory programs at Tela Botanica.
In ten years, more than 100,000 data on 470 municipalities have been transmitted. “Some territories are well sampled, such as Blois, Angers, Marseille, the Grenoble conurbation or around Clermont-Ferrand, but elsewhere, the sporadic nature of the collection does not always allow comparisons”recognizes Nathalie Machon, lead scientist at the National Museum of Natural History and co-author of Où if it caches biodiversityis in town ? (Ed. quae, 168 p., 19 €)
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Massive mobilization would allow it to complete several research projects, including that of measuring the effects of the ban on phytosanitary products (Labbé law 2017) or global warming on the quality of flora. To achieve this, Nathalie Machon unearthed an unexpected ally: the botanist Joseph Vallot, at the origin of an inventory of wild herbs in the streets of Paris in 1883. “Current species are much more resistant to heat and pollution than those of his time, and they no longer need horse manure to grow”, notes the researcher. His dream ? Publish a New flora of the cobblestones of Paris, 140 years after Vallot’s book!