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Cosmos atrosanguineus
Also called Black Cosmos
Chocolate cosmos is a tuberous perennial daisy from the mountains of Mexico, grown for its dark maroon flowers that smell faintly of chocolate. Give it full sun or light shade, well-drained soil, and dig up the tuber for winter in cold climates.
Cosmos atrosanguineus, the chocolate cosmos, is a species of Cosmos, native to Mexico. It has often been claimed that it is extinct in the wild; however it is truly abundant in Mexico. The species was introduced into cultivation in 1885, when the British seed company Thompson & Morgan first listed it in their seed catalogue. Its dark red to brownish red flowers have a scent resembling chocolate, which is one reason for its popularity as a cultivated plant.
Both seed-raised and vegetatively propagated cultivars are available, varying in the size, colour and shape of the petals. An article in 2017 listed 17 cultivars and seed-raised strains. As of 2018, C. atrosanguineus 'Hamcoec' (trade description Eclipse) has the largest flower heads, up to 5 cm in diameter. The variation in flower color from red to black of Cosmos atrosanguineus and its cultivars results from variation in the amounts of anthocyanins and chalcone present. Hybrids with other Cosmos species are also known in cultivation. As with Cosmos 'Thomocha' (Chocamocha), hybrids may be less scented than the species. Although cosmos smells like chocolate, it should not be eaten.
It requires partial sun or full sun, and flowers from mid to late summer. It is frost-sensitive (Zones 6–11); in temperate zones, the tuber has to be dug up and stored in a frost-free store over the winter.
Although it had been reported that Cosmos atrosanguineus was extinct in the wild, a research project on the genus Cosmos begun in 2007 by Mexican botanist Aarón Rodríguez found modern records starting from 1986. Field work showed that it grew in the states of Guanajuato, Querétaro and San Luis Potosí. It is found in mixed pine and oak forest, at elevations of around 1,800–2,450 m (5,910–8,040 ft).
Text excerpted from the Wikipedia article Cosmos atrosanguineus by its contributors, under CC BY-SA 4.0; the excerpts and the care summary drawn from them are shared under the same licence.
The care summary was written by AI (Claude, Anthropic) from the sources on this page, with general growing knowledge where they are silent. Check before relying on it.
Life form, climate and native range: World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 3.0), reformatted; see Plants of the World Online.
