Did You Know? Mexico's national flower is the humble dahlia

Tony Burton

Did You Know…?

With more than 30,000 native flowering plants to choose from, who would have thought that the humble dahlia would become Mexico’s national flower?

The earliest known description of the dahlia (known to the Aztecs as acocoxóchitl) comes from the Franciscan friar, Bernardino de Sahagún, who arrived in New Spain in 1529. The Aztec name is believed to derive from “plant with tube-like stems” and the Aztecs are said to have used them to carry water. The name was probably applied primarily to the tall, hollow-stemmed, tree-like species now known as Dahlia imperialis.

Later in the sixteenth century, the dahlia is described in the Codex Barberini, dating from 1552, and lost for centuries prior to its rediscovery in the Vatican Library in 1929. This codex, an Aztec herbal, was written by Martin de la Cruz and Juannes Badianus, two Indians educated at the College of Santa Cruz, Tlatelolco. It begins with maladies affecting the head, and proceeds towards the feet. The dahlia, we learn, was not only useful for carrying water, but also for treating epilepsy. Later scientists found that Atlantic starch, a kind of diabetic sugar extracted from dahlia tubers, was useful (prior to the development of insulin) in the treatment of diabetes.

A wonderful early description of dahlias comes from Dr. Francisco Hernández (1515-87), the first trained scientist to be sent to New Spain by King Philip II to research and describe the region’s natural history. After seven years exploring the Valley of Mexico, Hernández wrote The Natural History of New Spain, including descriptions of over 3,000 plants previously unknown in Europe. His timeless description of a dahlia was as a

“weed of more than medium size… with large, round flowers, purple with yellowish-red centers, with little scent. There are many varieties… distinguished only by the color and size of the flowers, which in some kinds are white, in others reddish yellow or purple or red, purple with white, red with yellow, or any of another thousand forms.” (loosely translated from the original).

This description demonstrates that breeding and propagation programs in pre-Columbian botanical gardens had already resulted in diverse varieties of the plant.

Hernández also decided that the dahlia was native to the state of Morelos, in the region around Cuernavaca and Tepozotlán. Modern botanists agree that the dahlia is native to Mexico and Guatemala, but how did it come to be cultivated so widely all over the world today for its showy flowers?

At the end of the eighteenth century, a physician, Martin de Sessé y Lacasta, and José Mariano Mociño collect plants for Mexico’s Botanical Garden, recording their findings in Plantae novae Hispaniae. Vincente Cervantes, a colleague of Sessé, sends some dahlia seeds to the famous Spanish botanist, Antonio José Cavanilles, in Europe. Curiously, Cervantes subsequently became director of the Mexican Botanical Gardens, while Cavanilles later became director of the Royal Botanical Gardens in Madrid.

The term “dahlia” is used for the first time in 1791, when Cavanilles publishes Icones et Descriptiones Plantarum. The name honors Andreas Dahl, a Swedish botanist, and the first variety is named Dahlia pinnata. Cavanilles sends some bulbs to Dahl, then residing in Denmark, thus beginning the spread of dahlias northwards across Europe. In 1795, Cavanilles names two more dahlia species: Dahlia coccinea and Dahlia rosea.

Independently of Cavanilles, the famous explorer Alexander von Humboldt finds a field of wild dahlias in 1803 and also sends seed back to Europe. His seed, which germinates and flowers in 1805, also turns out to be Dahlia coccinea.

Meanwhile, several attempts are made to introduce dahlias to the U.K., with numerous successes reported during the first decade of the nineteenth century. Among the pioneering growers are Richard Salisbury and John Wedgewood, who both write about their efforts for the Horticultural Society (which later becomes the Royal Horticultural Society). Wedgewood (1766-1844), the son of Josiah Wedgewood (founder of the famous pottery manufacturer), was actually one of the Soceity’s founders.

Fascination with dahlias takes flight at this time. By 1820, only about 100 dahlia varieties are being cultivated. This number explodes to more than 2,000 by 1840. Interest in dahlias wanes briefly until a fortuitous accident occurs in 1872, when the only surviving tuber in a box of dahlias sent from Mexico to Holland eventually yields a brilliant red bloom, with pointed petals, quite unlike any previous dahlia. This leads to a race to develop new varieties by crossing this red variety ( Dahlia juarezii) with earlier varieties. The rest, as they say, is history!

Strangely, no blue variety has ever been cultivated, hence “blue dahlia” is sometimes used figuratively for something impossible or unattainable. A prize of one thousand pounds was offered in 1826 for a blue dahlia, but no-one has yet managed to claim the prize!

Dahlias occupy a special place in many gardeners’ hearts, affording a spectacular range of types, sizes, and colors, ranging from small pompom blooms to amazing “dinner plate” flowers. The growing and advancement of dahlias has become big business worldwide. For instance, the Dutch dahlia trade is said to be worth some 50 million dollars a year, the second highest figure for floriculture after tulips.

In 1963, President Adolfo López Mateos decreed that the dahlia, one of Mexico’s numerous “gifts to the world”, should be the nation’s national flower. And so it remains today – a perfect symbol of the beauty and diversity found throughout the country.

Main Sources: