Manningtree, Brantham Felixstowe Chelsmford
Braintree Clacton. Frinton Hadleigh Woodbridge
Giant hogweed starts to grow in March and the plant can reach 5m in height. It has a firm, bright green stem with dark red or purple spots. The hollow stems vary in diameter, occasionally up to 10 cm. Each dark red spot on the stem surrounds a hair, and large, coarse white hairs occur at the base of the leaf stalk.
The leaves are dark green and form a rosette. The flowers are white, forming a large umbel. Each plant produces up to 50,000 seeds and these seeds can remain viable for up to 5 years.
The sap of giant hogweed is poisonous in humans, resulting in blisters, long-lasting scars, and—if it comes in contact with eyes—blindness. Which is also why great care should be taken when controlling giant hogweed.
Was introduced to Britain in 1893, again as an ornamental plant. It escaped from gardens and now colonises many areas of wasteland and riverbanks. Each flower head produces several thousand seeds that are easily dispersed by water allowing rapid spread along watercourses.
It forms dense colonies that suppress the growth of native plants an grasses, leaving the banks bare of vegetation in winter and increasing the risk of erosion.