Connectivity of green and blue infrastructures: living veins for biodiverse and healthy cities

Identifying urban plants

Recently I found a guidebook to the French flora of urban wastelands (Flore des friches urbaines, by Audrey Muratet, Myr Muratet, and Marie Pellaton).

This is a really beautiful book with lots of useful information. It has a section describing typical urban wasteland habitats and their typical plants, plant identification pages organized by family, a key, and a section on “plants in winter”. I immediately recognised many of the plants, since of course they are the ones you see all the time in a city, growing out of cracks in the sidewalk, filling abandoned lots, and lining railways.

What was also funny was that I recognised many of them from my PhD studying the effect of degu colonies on biodiversity. Degus are little rodents in Chile that I mentioned in the “Animal cities” blog post. On the sides of degu runways, and in the spaces in between, where they form “grazing lawns”, you find some of the French urban wasteland flora, such as Plantago spp. and Erodium spp., typical of “mineralized interstices” and “pioneer habitats” in European cities. The majority of plants in degu colonies, however, are native and endemic species. My reaction was less to worry about the homogenization of plant communities due to global plant invasions, and more a feeling of having recognised friends of friends—friends of degus and friends of urban humans.

This morning I went out with my new guidebook to the part of the “Petite ceinture” park along a former railway that goes through the 15th arrondissement of Paris. It was a freezing 5 degrees out—winter has arrived. It is tricky or impossible to identify plants that have died back for the winter, but since the weather was fairly warm up until this weekend, there is still lots of standing vegetation and even flowers. The first flower I saw was a plant with lots of little purple flowers arranged in circles of six up and down a tall stem. Next to it were dead stalks of the same plant, with little dry pale brown seedpods in rings of six. This seemed like it should be easy to identify, but after looking at all the purple flowers in the book I decided it definitely wasn’t any of them. Nor could I identify the taller branching flower stalk with little feathery pinecone-shaped dry flower heads, next to it. Things were not starting out well. On the other hand, along with these there were several Plantago lanceolata, which was easy to recognise.

Next I noticed several beautiful caramel-coloured dry flowers. This looked somewhat like the image of Achillea millefolium from the section on ‘plants in winter' but the colour of the plant in the image was darker and seemed to be spreading horizontally rather than standing straight up, so I wasn’t sure.

After a short wander I saw a tall (1.5 m) fuzzy pale brown stalk covered in the remains of flowers and a few small leaflets, with larger curled-up leaves at the bottom of the stalk. I had a vague memory that the flowers for this plant were probably pale yellow. My best guess, based on the flower ordering on the stem and the shapes of the dead leaves was that it was Verbascum lychnitis, but I wasn’t convinced.

A little farther on, I found some Asteraceae that might be Picris hieracioides or Hypochaeris radicata, as well as what I think were Erigeron boanriensis. Above them was a dry rust-colored plant that I’m not sure about what it could be.

Next I came across a large (1.5 m) plant that I recognised from the “prairies” section of the guidebook. But was it Armtemisia verlotiorum or Artemisia vulgaris? I figured this out from the book’s helpful comparison chart for these and Artemisia annua. Artemisia vuglaris has a flower head that is longer than it is wide, while the other two have flower heads that are wider than they are long. The tiny flower heads were definitely longer than they were wide, so it was Artemisia vulgaris.

A bit further on (and now very cold), I spotted a yellow flower. Approaching it, I realized that this was a flower of the tall pale brown, fuzzy stalk I had tried to identify before. Based on the flower, I confirmed that it was indeed Verbascum lychnitis. As I walked back, I looked again at the caramel-coloured dry flowers. Their leaves were delicate, curly and pinnate, which indeed corresponded to Achillea millefolium. The flowers in spring would be white or lavender.

I am not fanatical about identifying species for its own sake. Sometimes just knowing if its an animal or a plant, a reptile or an amphibian, a frog or a toad, is all you need to know to answer questions like, what is this? What is it doing? What does it need? What does it want? But other times, you have seen the plants and animals so often that you recognise them, but you have no words to talk about them. You know a little bit about them—compound flowers forming a flat surface attract many flies, bees, beetles and butterflies, for example—but witout names you have no words to talk to other people about those species to ask them questions and share observations. For example, because of this guidebook, I learned that the wild bee Anthidium punctatum uses the fuzz from Verbascum lychnitis leaves to make its nests! This would certainly be fun to look for in spring. When you know what you are seeing you can also start to interpret the history of a site: how long ago it was abandoned, what other kinds of disturbances it might experience, whether the soil is rich in nitrogen (maybe people pee there), etc. The wasteland goes from an empty space to full of intricate stories: stories linking places you know, and places you are just discovering.

--Meredith Root-Bernstein