Coleus

Appearance

"Coleus scutellarioides" is an upright annual or short-lived perennial plant. It may be as much as 1 m tall, with well-branched, more-or-less four-sided stems. Shorter, more trailing forms have sometimes been described as separate species, under names such as "Coleus pumilus" or "Solenostemon pumilus", but are all now considered part of the very variable "C. scutellarioides". The species is extremely variable in the colour and shape of the leaves. They are somewhat fleshy, varying in size from 1.5–10 cm long by 1–6 cm wide, generally ovate in shape, and borne on petioles from 0.5–5 cm long. The leaf margin is divided to a variable degree. Hairs are present on both sides of the leaf.

The inflorescence is borne on the end of a stem and, like the leaves, is very variable in size; it may be up to 4 cm long, with few or many flowers. The calyx is bell-shaped, initially only 1–2 mm long, but lengthening to 5–7 mm when in fruit. The bluish-purple petals are joined to form a typical two-lipped labiate flower, 8–10 mm long. The stamens are joined for about half their length and are covered by the upper lip of the flower. The fruit is described as a "nutlet", and is black, about 1 mm long.

Distribution

"Coleus scutellarioides" is native from southeast Asia through to Australia. It is cultivated worldwide and may be naturalized in other tropical regions. In its native habitat, it is found at elevations of 100–1,600 m, where it flowers and fruits throughout the year. It is winter hardy to USDA Zones 10–11.

Habitat

"Coleus scutellarioides" is native from southeast Asia through to Australia. It is cultivated worldwide and may be naturalized in other tropical regions. In its native habitat, it is found at elevations of 100–1,600 m, where it flowers and fruits throughout the year. It is winter hardy to USDA Zones 10–11.

Evolution

The species was first introduced into Europe from Java in 1851 by a Dutch horticulturalist. At this time, there were few leaf colors and shapes. A wider variety was available by 1877, when the American William Bull offered seeds at 43 US cents each. However, by selecting for seed production, early flowering was inadvertently favored, and leaf color also declined in intensity. Coleus breeding revived in the early 1940s, and by the 1980s, the availability of an improved range of cultivars led to coleus becoming the tenth most important bedding crop in the US. More recently, vegetative propagation has enabled cultivars with novel leaf colors and shapes to be offered for sale. Plants with trailing as well as upright habits are now available.