Two years ago, a very peculiar plant appeared in my garden. It had large, heart-shaped leaves, and it grew and grew, until it was four feet tall. Then, it developed tight, sunflower-like buds, which took ages to open. When they finally did, I was a little disappointed. It was a scruffy plant, with long, tatty petals, and the centre rapidly went from sunshine-yellow to a murky brown colour. I had no idea at all what it was. Some mutant garden flower, maybe? One sunny day, I was sitting next to the plant with my Flower Key open, when I discovered that it was called Elecampane.

I read that I was in the company of a very venerable plant. It is originally from Asia, but has been in the UK since before 1492, so this makes it an honorary native. It is also known as Horseheal, because it was extensively used in veterinary medicine. It was a sacred plant to the Celts, who knew it as Elfwort, and the Romans believed that it had sprung from the tears of Helen of Troy. The root was used both as a sweetmeat and as an effective cure for pulmonary disorders such as bronchitis and emphysema.

I looked at the plant with a new respect, and wondered how it had arrived in my garden. I have never seen it growing anywhere in the surrounding parks and gardens, and it was certainly not here when I arrived. But, here it is. And furthermore, its yellow flowers were attracting a creature that I’d not noticed before.

Wriggling around in the pollen at the centre of the bloom was a Patchwork Leaf-Cutter Bee (Megachile centuncularis). These bees do not have pollen sacs on their legs like honeybees and bumblebees, and so they rub their abdomen onto the flower so that the pollen sticks to the thick yellow hairs on their underside. This is the only plant in my garden that they currently visit.

Once, in the early spring, I was sitting in Culpeper Community Garden in Islington when I saw a leafcutter bee flying through the air, carrying a rolled-up leaf underneath it. These leaves are used to line the tunnels where the bees lay their eggs. They lay the female eggs first, in the inner part of the nest, and then the male eggs. The male eggs emerge first, so that they are ready and waiting for the females when they fly forth.

Until then, I had no idea that we had leafcutter bees in the UK – I always thought of them as rather exotic tropical insects. But here they were, cutting neat circles out of the wisteria and rose leaves.

What a series of happy accidents! First, a completely new plant appears in the garden, and then a new insect arrives to feed on it. There are lessons here for me about not being too tidy, and about growing a variety of different kinds of flowers – none of the other bees are keen on this plant, just as the honeybees have a marked preference for the Great Willowherb, and the bumblebees love the foxgloves. But above all, it reminds me to pay attention, and to be open and patient when new plants appear. It would have been so easy to just dismiss the Elecampane as ugly, and pull it up, and then I wouldn’t have had the pleasure of seeing the leafcutter bees, and they would have lost a valuable source of pollen. And these days, as we know, pollinators need all the help they can get.