Thunbergia erecta aka Bush Clockvine

Thunbergia erecta is a shrub from the tropics. It belongs to the Acanthaceae family. Its common names include bush clock vine and king's mantle. The RHS accepts Thunbergia erecta as its correct plant name. It is not native to Britain or Ireland. Its name includes vine, but Chicago calls it a shrub. It grows in a mound shape that suits beds and borders. The sources describe its flowers as its main source of color.

The blooms have a trumpet shape. Their petals are dark bluish-purple, with a golden throat. This bright throat stands out against the dark flower edges. Chicago lists the bloom colors as blue, purple, and yellow. These colors show the contrast within each flower. The listed bloom times run from May through December. They span late spring, summer, fall, and part of winter. This long listed season adds value to garden plans. The blooms pair dark outer parts with a bright center.

Chicago says full sun gives the best growth. It also lists part shade as a choice. Soil should stay moist but let excess water drain away. The same source says soil rich in humus suits it. These needs call for moist ground that drains well. The plant also prefers high humidity, or moist air. Moist soil and moist air are two distinct needs. Sun alone does not meet all the needs the source lists.

Chicago lists this shrub for USDA hardiness zones 10–11. That range fits a plant from the tropics. Gardeners should bear this narrow range in mind when choosing a site. Listed uses include beds and borders. Its mound shape suits its use as a shrub there. Chicago also lists it for use as a vine. That use does not change its stated class as a shrub. Birds and butterflies visit it, adding wildlife interest to its blooms.

Dry air can bring a pest problem: spider mites. Chicago links this risk to low humidity near the plant. Moist air thus matters for growth and for tracking pest risk. The source does not say the plant prefers dry air. It lists sun, moisture, good drainage, and moist air together.