VELCRO PLANT

Question I saw this in a garden recently and don’t know what it is. Can you help?

N. Baker, Auckland

Answer This looks like burdock, Arctium minus, or the closely related A. lappa. It’s in the thistle family yet the leaves and stems have no prickles, just the flowers and seeds. There’s a story that the tiny hooks on the end of its seed prickles, which Swiss engineer George de Mestral found sticking to his socks and his dog’s coat in 1941, led to him developing the Velcro fastening system.

The plant can grow a metre or so high, produce masses of seeds, and in some regions of the country is listed as a pest plant. The Auckland Council Pest Management Plan states, among other rules, that “You must not breed, distribute, release or sell burdock within the Auckland Region.” On the other hand, burdock is known widely for its edible and herbal properties, particularly from its long, fleshy tap root. So if you grow burdock for its positive attributes, make sure to remove the spent flowers to prevent seed spreading this potentially harmful plant.