The family Bidens (DK: Brøndsel) is spread in Europe and in North and South America. They are herbs and bushes with opposite leaves and small composites of yellow flowers in august-September. The fruits are equipped with barbs.The Burr Marigold is common at ponds, village ponds, lakes, in pit bogs, ditches etc. The Bidens cernuus grows in the same habitats but is not as common as the tripartita. The common names beggarticks, black jack, bur-marigolds, stickseeds, tickseeds and tickseed sunflowers refer to the burrs on the seeds, most of which are barbed. The generic name refers to the same fact; it means "two-tooth", from Latin bis "two" + dens "tooth".
The old Danish name Bryndsel means ildebrand (fire), because the flowers dye fabrics in a strong yellow hue called brandgult ( fire yellow).
The plants are zoochorus; their seeds will stick to clothing, fur or feathers, and be carried to new habitat. This has enabled them to colonize a wide range, including many oceanic islands. Some of these species occur only in a very restricted range and several are now threatened with extinction, They were and are still used to make a refreshening tea. Some of the species are sometimes eaten as a vegetable, others are very bitter, others are fine honey plants - and several Bidens are used as food by caterpillars of certain Lepidoptera, like Painted Lady.
The Burr Marigold is mentioned in Denmark in 1670 among plants, which dye a strong yellow. The flowers with alum dye yellow, the flowers with potash dye a strong light yellow (1795) - the flowers were ab. 1800 used for yellow dye in general , fx at the island Bornholm. The plant itself dyes red-yellow and golden-brown.
In the autumn the sheep was given Burr Marigold as a protection against worm and disease. (1761).
Source: V. J. Brøndegaard, Folk og Flora, Dansk etnobotanik, Rosenkilde og Bagger, 1980;
Danmarks fugle og natur; Naturegate; Wikipedia; Gyldendal, den store danske; Danmarks flora.
photo September 2010/2011: grethe bachmann