This is the season when Swiss farmers’ cover crop, purple tansy aka its official name of Phacelia tanacetifolia, suddenly begins to bloom all around us. The flower is beautiful if somewhat understated – a field of solid flowers remains a muted purple compared to lavendar or the blue of linseed in flower. Bees love it and farmers are planting it partly to encourage the bee population. Hoverflies, who eat aphids, also love it, so it makes a good biological control crop.
For the rest of us, seeing it against a skyline of Alpine peaks or an old shed, it is simply one of the delights of autumn in Switzerland. Details on Wikipedia, Gardening Knowhow and Bountiful Garden.
A word of caution, if you’re tempted to plant it: it’s a spreader, with rhizomes and seeds that you might not want everywhere!