- Name also: Downy Burdock
- Family: Daisy Family – Compositae, subfamily Carduoideae
(formerly Aster Family – Asteraceae)
- Growing form: Biennial herb. Strong-rooted.
- Height: 50–150 cm (20–60 in.). Stem branching, rough, densely short-haired, woolly base.
- Flower: Single flower-like approx. 2.5 cm (1 in.) capitula surrounded by involucral bracts. Capitula’s ray-florets lacking, disc florets purple, tubular. Stamens 5. Pistil of 2 fused carpels. Involucre virtually spherical, woolly (occasionally glabrous). Involucral bracts overlapping in many rows, long, branched, narrowly lanceolate, rigid, green–brownish, outer bracts reddish with yellow hooked tips, inner bracts with straight tips. Capitula borne in a corymbose cluster.
- Leaves: Alternate, stalked, stalks with tomentum (woolly hair) when young. Blade broadly ovate, often cordate-based, sharp-tipped, small-toothed, dark green on top, hairy along veins, underside densely grey-cottony (tomentose).
- Fruit: Oval, slightly curved, bristly, light brown–greenish grey, black-flecked achene, tip with short, yellow barbed down.
- Habitat: Yards, meadows, roadsides, wasteland, around old inhabited areas. Nitrophile.
- Flowering time: July–September.
Woolly burdock is a typical example of a plant that has followed old culture and which has been a familiar sight in people’s back yards, around gardens and against the walls of farm buildings since ancient times. Its complete capitula attach themselves via their hook-tipped involucral bracts and move easily on e.g. animal fur to new habitats. Before people and animals came along woolly burdock has probably been carried by the large mammals that were around after the Ice Age. It puts all its resources into producing its large inflorescence and is fatally exhausted by its endeavour, so it must be for a reason. Its capitula rise two metres (6.5 feet) above the earth and would be just the right height to latch on to a passing mammoth.
Throwing burdock capitula at people has probably been a pastime for Finnish children since the Stone Age. Apart from this, they have also been used to card wool and even hunt bats. The cypselas themselves have no hooks – some are entirely lacking down or it is too inconsequential to act as any kind of parachute – so they have no real means of spreading on their own. The shoots remain erect throughout the winter and provide nutrition for some birds. Goldfinches are particularly partial to burdock seed but they are probably not much use in helping the plant spread, and different kinds of insects destroy a large proportion of the seed.
Large plants usually have identifying markers that allow them to be easily classified, but burdocks aren’t easy to define. Woolly burdock can be told apart by the down that looks like it has been woven by a spider and covers the outside of the capitula – none of the other Finnish burdocks have anything like as dense a woolly covering. Woolly burdock cross-breeds with both greater burdock (A. lappa) and lesser burdock (A. minus)