Common Name:

General Information

Dahlia coccinea is an erect herbaceous plant with unbranched to sparsely branched stems; it can grow 50 - 150cm tall, occasionally reaching 300cm[, ].
The tuberous roots were commonly used for food and medicine in pre-Columbian Mexico, and are still eaten to a limited extent in the present day[]. Gathered from the wild, they are sometimes sold in local markets[]. The plant, however, is now more likely to be cultivated for its ornamental red, orange, or yellow flowers[].

Known Hazards

None known

Botanical References

,

Range

C. America - El Salvador, Belize, Guatemala; southern N. America - Mexico

Habitat

Damp or dry, often rocky, open or brushy slopes, often in oak or pine-oak forest; at elevations from 1,100 - 3,000 metres[].

Properties

Edibility Rating
Medicinal Rating
Habit	Perennial
Height	1.00 m
Pollinators	Insects
Self-fertile	No
Cultivation Status	Ornamental, Wild

Cultivation Details

Most Dahlia species in Mexico grow at moderate to higher elevations, typically above 2,100 metres in southern Mexico, where there can be rapid changes in temperature, but no frosts[]. The dahlia’s home area in the volcanic highlands of southern Mexico is hot and dry during the winter months but the rainy season during summer is characterized by afternoon thunderstorms. Also, dahlias are adapted to grow while being bathed in dew from the low hanging clouds[].
Dahlia species in the wild are generally found on well-drained hillsides, rough banks and cliffs. The soil is typically a soft, porous and sandy loam with a gravelly subsoil which is often volcanic and mildly acidic[].
Dahlia tubers are worth some experimentation as a root crop either for food or for sugar production since their root sugar content is quite respectable even without artificial selection. For example, up to 15 sweet potato-sized tubers, containing as much as 13% fruit sugar, can be produced by a single plant in one season under optimum conditions. This high sugar content, even among wild dahlias, compares favorably with sugar beets, even though sugar beets have been scientifically selected so that their sugar content has been increased from 7% to 20%. Such scientific breeding could lead to a similar increase in the sugar content of dahlias if they become recognized as a worthwhile agricultural plant[].

Edible Uses

Tuberous roots were eaten in pre-Columbian Mexico[].
There are contradictory reports regarding the edibility of Dahlia tubers, ranging from sweet and juicy to extremely bitter, hot and dry tasting and virtually inedible. This could be due to the time of year the tubers are harvested. If gathered at the beginning of the rainy season - after the inulin had been converted by enzymatic action to produce fruit sugar and before the rapid growth of the tall stalk had depleted the tubers of food - then the tubers would, indeed, have been sweet tasting and juicy. In the second case, if the tubers were gathered late in the growing season or at the beginning of the dry season - before the return of the plants’ food and water resources back into the tubers for storage -then the medicinal constituents of the depleted tubers (especially the skin) could have been expected to give a potent and unpleasant taste. In short, dahlia tubers to be eaten raw immediately should be harvested in the spring, and those intended for medicinal use should be gathered later in the summer when the growing season is well advanced but before the start of the dry season and those intended for baking or storage as food should be gathered well after the start of the dry season when the upper parts of the plant have wilted down in the manner of potato stalks and the tubers are full of inulin, which keeps well[].

An essential oil found in the tubers yields benzoic acid. This is probably the main active ingredient in the plant. It has been used as a food preservative as well as a topical keratolytic fungicide/bactericide, an antiseptic mouth-wash, a diuretic and an expectorant. It is rapidly excreted from the body as hippuric acid, and in large doses increases the output of uric acid. It is actively germicidal at pH 3.5 but only bacteristatic at pH 5.0. Exfoliation of the upper layers of skin is produced by keratolytic action.
This desquamation makes deep infections such as athlete’s foot and ringworm of the scalp accessible to even more potent ingredients which may be mixed in with benzoic acid in an ointment[].
Eriodictyol, an active ingredient first found in the plant Eriodictyon californicum, has been used as a bitter tonic, expectorant, astringent, and in the treatment of asthma[].

Medicinal

The tubers have antibiotic and antiatherogenic (used to treat atherosclerosis) properties, and also act as central nervous system depressants[].
The tubers were used traditionally as a tonic, diuretic and diaphoretic, and used in the treatment of colics and flatulence. The roots were said to be soft, full of juice like the ones of the day-lilly, somewhat yellow inside, resinous and sweet tasting[].

Other Uses

None known

Propagation

Seed - usually germinates in 1 - 3 weeks at 20°c[]. When they are large enough to handle, prick the seedlings out into individual pots and grow them on until large enough to plant out.
Cuttings of young shoots as new growth begins.
Division of the tubers when dormant. Each portion should have a growing point[].

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