Common Name:

General Information

Cosmos sulphureus is an erect, branched, annual plant, usually growing up to 120cm tall, but in rich soil it can reach 200cm[, ].
The plant is harvested from the wild for local use as the source of a dye and as a medicine. It is commonly grown as an ornamental, there are many named varieties[, ].

Known Hazards

None known

Botanical References

Range

C. America - Guatemala, Mexico. The plant has been widely cultivated as an ornamental and is found in much of the tropics and subtropics.

Habitat

A common roadside weed in Africa, which does not spread into undisturbed localities[]. Adventive, along roadsides, in damp meadows, on brushy slopes, also cultivated and escaping as a garden weed, mostly at elevations from 1,100 - 2,100 metres[].

Properties

Weed Potential	Yes
Medicinal Rating
Other Uses Rating
Habit	Annual
Height	1.00 m
Pollinators	Bees, Butterflies
Cultivation Status	Ornamental, Wild

Cultivation Details

Grows best in a sunny position[]. Succeeds in most well-drained soils, though in very fertile soils the plant grows much taller and tends to flop over[]. Succeeds in poor soils and in dry soils[].
The plant often self-sows very freely, particularly if the seed falls on bare ground. It can behave as a weed, though it tends not to invade undisturbed areas[, ].
Removing the flowers as soon as they are past their best, and before the seed starts to form, will greatly prolong the flowering season[].

Edible Uses

None known

Medicinal

The rhizomes are used in the treatment of malaria[].

The traditional medicinal applications in China of Cosmos and Bidens species have been confirmed by the fact that Cosmos and Bidens extracts are shown to inhibit bacteria, fungi, and viruses and to have potent anti-inflammatory effects in laboratory animal experiments with induced gastric ulcer, liver inflammation, or arthritis-type swelling[].

The plant has yielded butein, known for its antioxidant and antiinflammatory activities[].
An ethnobotanical study showed the plant to have activity against the parasitic, mosquito-causing protozoa 'Plasmodium'[].

Other Uses

The flower heads of this species, plus many other Cosmos, Bidens and Coreopsis species, were major sources of yellow to orange dyes among the pre-Columbian civilizations of Central and South America. In southern Africa, they were adopted as a popular yellow dye by European settlers for domestic textile production and are still used by dyers using natural dyes as a hobby or for textile crafts, to dye wool bright yellow or orange[]. The flowers should first be boiled for about one hour before adding the mordanted wool to the cooled dye-bath and resuming boiling. Pre-mordanting the fibres with different metallic salts gives various shades of lemon yellow to burnt orange. As a top-dye after a first red dyewood bath (e.g. of Baphia nitida Lodd.), it helps give a scarlet bloom to wool while on indigo-dyed wool, it produces greenish-brown shades[].
The flower heads of most Cosmos, Bidens, and Coreopsis species contain flavonoid dyes of the chalcone and aurone groups. The specific flavonoids in Cosmos have not been fully elucidated, though the following have been found: luteolin, a group of flavonols having quercetin as their aglycone, and a group of chalcone glycosides. These are all good yellow colorants[].
The flower heads of about two dozen plants are sufficient to dye 0.5 kg of wool or silk. They should be harvested when they open. They are soaked in water and the mixture is cooked until the flower heads become pale. The dye bath is yellowish in an acid solution (e.g. With vinegar) and reddish in a basic solution (e.g. With ammonia or washing soda). Alum and tartaric acid are often added as a mordant. The textile is simmered in the dye bath until the desired depth of colour is achieved, usually after about one hour[].

Propagation

Seed - sow in situ.

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