Thryallis is a small evergreen tropical shrub that grows to a maximum height of about 6 ft (0.6 m) and about as wide. It grows moderately fast into a neat rounded shape with many slender stems that are reddish when young. This shrub forms a dense and twiggy mass covered in light green oblong leaves. These are arranged oppositely and are 1-2 in (2.5-5 cm) long and take on bronze tones during cooler periods. Thryallis smothers itself in beautiful yellow blossoms in late summer and fall although some flowers can be expected at all times if warm temperatures are maintained. The yellow flowers are about 3/4 in (2 cm) in diameter and are held in 4-6 in (10-15 cm) clusters at the stem tips. Flowers are followed by interesting three part seed capsules.
Galphimia glauca is native to the tropical areas extending from Mexico to Guatemala in Central America.
Occasionally remove "leggy" stems to keep the plant from looking scraggly.
Light: Bright sunlight is prefered. Plants grow more scraggly in shady area and trimming may be required for neatness.
Moisture:Likes well drained soils. Thryallis is drought resistant and does well in dry sandy soils.
Hardiness:USDA Zones 9 - 11. Root hardy in Zone 8. Thryallis can take some frost and freezing. May be killed to the ground by temperatures less than 30ºF (-1ºC).
Propagation: By seeds. Also by cuttings taken in the summertime.
This shrub is one of the best for shearing into low hedges. Use in foundation plantings beneath windows where it's dense thicket of stems will discourage prowlers. Thryallis makes a great background plant for perennial beds. Mass this shrub for large scale groundcovers. Useful for preventing hillside erosion. Thryallis is also happy in containers as well as in greenhouses and conservatories where it is glad to brighten up the situation with quantities of bright yellow blossoms.
Forms dense barriers that are attractive and functional. Thryallis is a good candidate for low-maintenance landscapes, it is easy to grow, drought resistant, and blooms almost all year around.
You may see this plant referred to by an older name Thryallis glauca in some references.