CERATOSTIGMA. Himalayas to Africa. Charming relatives of the common plumbago (Plumbago auriculata). They are twiggy perennials and shrubs with attractive pointed-oval leaves, often tinged with red in cooler weather. In late summer and fall they carry many clusters of blue flowers, flaring widely from a narrow tube, at the shoot tips. Sun or light shade, most soils, moderate watering. Their hardiness varies as shown below.
griffithii. Mounding in habit, growing 2-3' tall. It is thickly clothed with bluish green leaves about 1" long. The flowers are up to 1" across and painted bright, true blue. The plant is basically evergreen, though nipped back at times by hard frosts. 10oF or less.
minus. A deciduous 2-3’ shrub, growing nearly erect in the current form. The leaves are 1-2" long, broader near the tips and dark green above, paler and bristly beneath. It flowers in late summer and fall, carrying dense clusters at each node of the younger stems. The flowers are a little under an inch broad and colored bright blue on the spreading “faces”, purple on the tubes. 10oF. or less.
plumbaginoides (Plumbago larpentae). This species travels by underground rhizomes to make lush carpets of seasonal shoots, each up to 1' tall. It has dark, softly shining leaves, which turn deep red in the fall and winter before dying back for the season. The flowers are about 3/4" across and colored a spectacular deep blue, seeming to glow from within. Hardy to below 0oF.
willmottianum. Chinese plumbago. A spreading 2-4' shrub with reddish, zigzag stems and deep green 1-2" leaves. These are often vividly colored in fall. Bright blue 1" blossoms are clustered at the shoot tips over most of the summer and early fall. 10oF or less.