Viguiera dentata, known variously as sunflower goldeneye, toothleaf goldeneye and other names, is a commonâÂÂsometimes abundantâÂÂand weedy wildflower species throughout its mostly neotropical distribution area. At its flowering peak it may present spectacular displays. It belongs to the family Asteraceae.
Viguiera dentata at first looks like numerous other aster family species with yellow flowers. To be sure of its identity, it may be necessary to note these details:
Viguiera dentata occurs in the Southwestern United States in the states of Arizona, New Mexico and Texas. Mostly, however, the species is native throughout Mexico, Cuba and Central America, entering South America in Colombia.
In the US, Viguiera dentata occurs on dry slopes, in canyons, fields and roadside ditches up to 2300 meters in elevation (~7550 feet). In highland central Mexico often it's abundant in secondary vegetation of different kinds including roadsides, also in forests of oak, conifers, and in tropical forest with deciduous leaves where extended dry seasons occur, and dry scrubland, up to 2900 meters (~9500 feet).
Viguiera dentata demonstrates as allelopathic effect inhibiting the germination of certain tropical weed seeds, thus having a potential for use as a bioherbicide in tropical crops.
During photosynthesis, Viguiera dentata employs the C<sub>3</sub> carbon fixation pathway. In full sunlight the plant may grow almost twice as tall and develop twice as many secondary shoots, or tillers, and develop 54% greater dry weight, and 5 times as many flowers, as plants growing in shade. However, shaded plants develop 48% more leaf area per plant, mainly due to bearing more leaves per plant.
Noting that the inhabitants of San Rafael, Coxcatlan, Puebla, Mexico used infusions of aerial parts of Viguiera dentata to treat baby rash, it was found that bacteria were sensitive to essential oil from the species, though the oil showed no antifungal activity. Also in Mexico, in the state of Sonora it's used as an antiseptic and in Quintana Roo state to suppress coughing.
In Mexico's Yucatan Peninsula, where the Mayan people traditionally have produced much honey, 40% of annual honey production has been attributed only to Viguiera dentata.
In Mexico's dry Yucatan Peninsula where grain crops may be scarce but Viguiera dentata grows abundantly, it was found that, though pregnant pigs gained more weight on a diet with sorghum and soybeans, they did well on a diet containing up to 50% Viguiera dentata, both freshly collected and as silage. Because of the high cost of grain livestock feed and the low cost of feeding Viguiera dentata, it was found that in an economic sense supplementing pregnant pigs with that plant was very advantageous.
In Mexico's Yucatan Peninsula, where Viguiera dentata grows tall in dense populations, the stems can become exceptionally straight for up to 2.5 meters (over 8 feet), and be light and smooth. Artisans use such stems as bases for rockets which explode for fireworks and make loud noises during festivities. Such stems keep the rockets flying more or less skyward.
In the US, wildflower gardeners appreciate Viguiera dentata because it is extremely drought-tolerant on various dry, calcareous soils. Also, in October and November it produces colorful flowers with nectar for bees and butterflies while through most of the winter it provides forage for seed-eating birds, and reseeds readily under favorable conditions. However, it's vulnerable to deer.
Edward Schilling in Flora of North America remarks that "It is likely that the genus will be narrowed to include only a single species, V. dentata (including V. helianthoides Kunth), and that new or resurrected genera will accommodate the remaining species. The mentioned V. helianthoides now is regarded as a synonym of Viguiera dentata var. dentata.
The genus name Viguiera honors Louis Guillaume Alexandre Viguier, the author of Monographiæ de Papavere.
The species name dentata is from the Latin dentatus derived from dent-, meaning "tooth." Probably the name reflects the taxon's toothed leaves, though sometimes the teeth are very small.