The Biological Control of the Weed Clidemia hirta, D. Don., in Fiji

Abstract

The plant Clidemia hirta belongs to the natural order Melostomaceae. It is of shrubby growth, with a hard tough stem and produces quantities of dark purple berries, filled with minute seeds. These berries are much relished by certain birds, which feed upon them and distribute the seeds. The leaves are covered with fine hairs and the plant is not eaten by stock.The plant is a native of the West Indies, Central America and the Northern portion of South America. It is supposed to have been introduced into Fiji from British Guiana at some time prior to 1890. That this was the origin of the plant is supported by slight differences observed by the writer in the foliage of the Trinidad, Panama and British Guiana forms of the plant, the Fijian one closely resembling those of the last named country.In Fiji the plant was first observed along the fences of paddocks in the Waimanu Valley, whence it spread with great rapidity, quickly becoming a weed of major importance. By 1919, when the writer arrived in the country, thousands of acres were covered with it to the exclusion of almost all other growth. On good soil it formed a stand five or six feet high, through which the cattle were only able to keep open narrow paths. Not only did it rapidly occupy the open grass lands, particularly the rich dairying and fattening country, but it thrived almost equally well under the shade of coconut and rubber plantations, leading to loss of many fallen nuts and entailing greatly increased weeding costs.