On July 22nd 2021 about 11.30am I decided to take a walk around my neighbourhood just for the exercise. During these walks, I always carry my camera with me. Amongst other pictures taken, was this white flower which I discovered growing on a fence near my home. I would not have seen it if I didn’t make the detour from the usual route back as some poeple were fogging the path. I found the Koster’s curse!
In the 1880s, a guy named Koster accidentally introduced Clidemia hirta to a coffee plantation in Fiji (Nelson, 2010). It spread throughout the island after that, thereby becoming a curse of sorts, hence leading to the common name Koster’s Curse. Birds eat the fruits and disperse the seeds.
Clidemia hirta, commonly called soapbush or Koster’s curse, is a perennial shrub. It is an invasive plant species in many tropical regions of the world, creating serious damage. Very much a common herb with a shrubby habit, and frequently found on forest edges. One thing unique about this plant is that every part of it is covered with dense hairs, from the leaves to the stems and even the fruits. The leaves are also quite recognisable, having deeply furrowed secondary and tertiary veins. This densely branching long-lived (perennial) shrub normally grows to 0.5–3 m tall, but sometimes reaching 5 m in height, depending on habitat. In more shaded habitats it grows much taller than it does in exposed areas, where it typically grows less than 1 m tall.
The younger stems are rounded and are covered in large, stiff, brown or reddish-colored hairs (they are strigose). The oppositely arranged simple leaves are borne on stalks. They are oval or egg-shaped in outline with broad end at base, with pointed tips, and almost entire to finely toothed margins. Their upper surfaces are sparsely covered in hairs, similar to those found on the stems, while their lower surfaces and margins are more densely hairy. The leaves also have a somewhat wrinkled appearance and five distinct veins that run in an almost parallel fashion from the leaf bases to their tips.
The flowers are arranged in small clusters at the tips of the branches. Each flower is borne on a very short stalk and has five white, or occasionally pale pinkish, petals. The base of the flower is swollen into a cup-shaped structure which is moderately to sparsely covered with a mixture of bristly and sticky hairs. The flowers also have five sepals, but these are very small, and five distinctive stamens that have a claw-like appearance.
The small, rounded fruit are berries and are either dark blue, purplish or blackish in color. Each of these berries contains over 100 light brown colored seeds. These fruit are also covered in stiff spreading hairs, especially when they are young.
In terms of economic uses, Clidemia hirta has been widely introduced as an ornamental plant. The purple-brown to blue-black berries are up to 8 millimetres (0.31 in) long and taste a bit like a deeply flavored blueberry.
It flowers and fruits all year, if conditions are moist enough. A large plant can produce more than 1,000 fruits in a single year producing thousands of seeds. The seeds are dispersed by birds, feral pigs, other animals, and humans. Sheep will not eat the plant, and the tannin inside the fruits is poisonous to goats. Biosecurity trials in Australia show that the seeds can remain viable in the soil for at least 12 years.
The human edibility factor of this berry has not been fully explored. The tannin inside of the fruit is not harmful to humans and a delicious syrup may be made from the fruit. The syrup has a beautiful indigo blue color and may be used to enhance and remove the bitterness of teas such as yerba mate. Furthermore, the plant is used in Brazil to treat Leishmania braziliensis skin infections
The plant is harvsted from the wild for local use as a food and a medicine. It is cultivated in tropical areas for its edible fruit. A plant of the moist tropics, it grows in areas that are usually characterized by very high humidity for most of the year with a dry period of about two to three months. Fruit – raw. Rich in vitamin C. Sweet and pulpy. The blackish, dark purple, bluish or red, fleshy fruits are 5 – 7mm in diameter containing many minute seeds.