Mexican Petunia

The Ruellia simplex, still widely sold as Ruellia brittoniana and known everywhere as the Mexican Petunia, is an upright sub-shrub of 0.9 to 1.2 metres carrying narrow dark green leaves and violet-blue trumpet flowers that open fresh each morning through the warm months.
It is unusually indifferent to soil, taking heavy wet ground and dry ground with equal calm, which is why it turns up in medians, pond margins and mass bedding alike.
The Mexican Petunia is one of the most adaptable flowering fillers available, covering wet and dry ground in the same planting palette.