Ceratostigma minus

From the Sichuan and Yunnan provinces of China comes another of the great, but little-known, pure blue-flowered leadwort species. C. minus is similar to the popular C. willmottianum, except that the flowers, which top the loose clump of dark stems and small green leaves from midsummer through fall, are slightly lighter blue than the latter. C minus is a great mingler in the garden (not to be confused with the more aggressive C. plumbaginoides, which can be a Mengele in the garden.