Lobelia pubescens is a spreading herb that may be either annual or perennial. Its flowers are white or pale blue, up to 1,5 cm long. This blue one grew unexpectedly in a container carrying a Senecio plant at Onrus. So the leaves visible here should be ignored.
The flowers have the typical Lobelia two-lipped structure, the upper one being small, two-lobed and split to the base, while the lower one has three bigger, rounded lobes. There is a white patch in the centre of the lower lobes of the blue-flowered form.
The two lower anthers have tufts of white hairs at their tips. The straight, thin calyx lobes spread in star-shape away from the corolla base. There are still some purplish brown buds waiting to open in the flower cluster (Manning, 2009; Bond and Goldblatt, 1984).