[Overview]
An annual or perennial.
The stem is erect.
Leaves are simple and opposite, with entire margins or with teeth or serrations.
Flowers are borne singly in the leaf axils, in cymes, or in panicles at the stem tips.
The flowers are funnel-shaped, with 5 nearly equal lobes at the tip.
The fruit is a rod-shaped capsule.
[Cultivation]
Propagate from seed, by cuttings, or by division.
Light requirements differ depending on the type.
It prefers well-drained, fertile soil.
Take care not to overwater; for potted plants, water thoroughly when the soil surface dries from spring to autumn, and keep on the dry side in winter.
For plants in the ground, rainfall is sufficient.
From spring to autumn, apply slow-release fertilizer placed on the soil.
There are no particular pests or diseases.
