A plant that has attracted much attention because of its poisonous properties is tutu, a shrub growing, at most, to a height of about 20 ft. It occurs in shrubland and in open places in coastal and montane forest throughout New Zealand and the Chatham Islands. It often comes in profusely on cuttings running through damp forest. It is a straggling plant, much branched from the base and with four-angled branches. The leaves are opposite and on slender stems, the whole looking like a pinnate leaf. Each leaf is 1–3 in. long, about broad-ovate and acute. The small flowers are arranged in drooping racemes, 6 in. or more in length. The petals, later juicy and purplish-black, embrace the fruit.
The poisonous principle is a toxin, tutin, which occurs in all parts of the plant except the fleshy petals. Tutu has been responsible for the greatest percentage of stock poisoning by plants in New Zealand. Sheep and cattle are mostly affected. Occasionally poisoning of human beings by honey has been attributed to the honeydew from tutu which has been collected by bees.
The genus Coriaria is the only one of the family Coriariaceae. There are about 30 species, mostly shrubs, found in southern Europe, eastern Asia, south and central America, and New Zealand where there are seven other species besides that of C. arborea. Most of these are small shrubs with small leaves. C. plumosa, for example, is a prostrate plant under a foot high with leaves a fraction of an inch long only.
by Alec Lindsay Poole, M.SC., B.FOR.SC., F.R.S.N.Z., Director-General of Forests, Wellington.