Lobelia purpurescens (Pratia purpurescens)
The friend who gave me this plant for my garden couldn’t understand why I wanted it. “Once you have it, you’ll never be rid of it”, she warned me.
She was quite right, but actually I’ve never really wanted to be without it.
It’s a pretty little thing, which gracefully fills in the gaps between other plants and is ornamented with a sprinkle of little white flowers for more than half the year. Its dark green leaves are backed with purple. It wanders where it pleases, hugging the ground in half-sun (or if mown), and growing a little taller in well-watered shade. Full sun is too much for it.
I doesn’t really qualify as a “groundcover” in the sense that it grows only as a rather open plant. This is not something to plant as a weed-excluder, but has the converse virtue that it co-exists happily with anything, even small plants, that you might want to plant in the middle of a whiteroot patch.
In this photo taken in Franke Scrub, it is growing very lushly in damp, shaded soil - yet it has survived happily in my garden with no supplementary watering, through the droughts of the last few years.
It is a frost hardy plant.