[Overview]
A perennial.
The stem is erect and square in cross section.
The leaves are simple and opposite, with toothed margins.
A flower spike at the stem tip bears many flowers.
The flowers are lipped; the upper lip of the corolla is erect, and the lower lip is 3-lobed with a broad, large central lobe.
There are 4 stamens, which project far out of the flower together with the pistil.
Flower colors include blue, purple, white and pink.
The calyx is tubular and 5-lobed.
The fruit is a schizocarp.
[Cultivation]
Propagate from seed, by division, or by cuttings.
It also spreads readily by self-sown seed.
It prefers sun to partial shade and slightly moist, well-drained soil.
Water thoroughly when the soil surface dries.
From spring to autumn, apply slow-release fertilizer placed on the soil.
If cut back after flowering, side shoots grow and a second flowering can be enjoyed.
There are no particular pests or diseases.
