Hailing from the volcanic mountainous region of central Mexico, the common garden cosmos, Cosmos bipinnatus, is one of the most widespread annual flowers in the world, being found on all continents except Antarctica. From its humble origins it has been cultivated and bred for less than a hundred years and yet today the variety of flower forms available is truly staggering.
Cosmos bipinnatus is a weedy annual herb found on disturbed fields and roadsides across the globe. Growing from 0.3 – 2.0 meters or more high, it tends to have a rambling habit, particularly as it grows taller. The complex pinnate leaves are composed of very narrow leaflets that are twice divided (bipinnate) and held in opposing pairs, giving them an airy, feather-like appearance.
The flower heads are borne singly on long stems (peduncles) held well above the plant, are usually 5-7 centimeters across, but can be up to 10 centimeters in selected varieties. Flower heads are made up of two flower types – small centrally clustered disc flowers surrounded by a ring of ray flowers with lobed petals (corollas) up to 5 centimeters long. Disc flowers typically are bright yellow and the corollas of the ray flowers range from pure white thru various shades of pink and purple. The dark brown, elongated seed is produced in large quantity, enough to make this a potential weed in warmer climates.
The natural distribution of C. bipinnatus is somewhat obscure with most sources (including efloras) stating “Mexico and the southwestern U.S.”, though in all likelihood it is originally from central Mexico. Regardless, nowadays the species in both its cultivated and self seeding forms can be found all around the globe in open fields, roadsides, or any other human disturbed ground. North of the Mexican border it has been recorded in 36 states of the U.S. as well as two Canadian provinces, where apparently it is self-seeding, at least on some sites. It has also been recorded throughout all of Japan south of Hokkaido, where it is both self-reproducing and cultivated.
So what is the attraction of this short lived herb? It’s irresistible, variably colored flowers of impeccable symmetry, are the obvious answer. It is said they were given the name “cosmos” by Spanish priests who grew them on mission grounds due to the perfect symmetry of the flowering heads (cosmos comes from the Greek word κόσμος, meaning the order of the universe, or the opposite of chaos). Since those early days of cultivation, breeders have taken this lowly annual herb and created an astounding range of flowers.
Keeping up with all the names of varieties that have been made is a large task. Here is a representative list of some of the more well known ones:
Picotée – white petals with pink to red marginal bands.
Sensation Series – large flowers, color varying from carmine through pure white. Average height, up to 2 meters.
Sea Shells – tubular trumpet-like fluted petals in variable shades of pink.
Sonata Series dwarf mix – Fleuroselect Awarded variety with large flowers on a relatively short plant (up to 60 cm). Like the Sensation Series, flower color is variable. Also given the Award of Merit by the Royal Horticultural Society.
Candy Stripe – similar to Picotée with pink to red margins.
Double Take – large, double to semi-double flowers up to 10 cm.
Gloria – bi-color flowers with a dark pink to red center.
Psyche Mix – Semi-double, frilly flowers from burgundy to white color.
Purity – pure white flowered variety.
Pinkie – as the name suggests, a pink flowered variety.
Radiance – flowers with a pink to red center, similar to Gloria.
Dazzler – deep carmine red flowers with yellow centers up to 10 cm.
Cupcakes – petals fused together, forming a bowl shape, white flowered fading to pink.