Plant Story: Zinnias, American Wildflowers

Zinnias are common and familiar garden flowers, in the genus Zinnia, sunflower family, Asteraceae. They come at the end of the alphabet in lists of garden flowers and indexes. Neither edible nor much of a medicinal, zinnias get little comment beyond "easy to grow."

The more I read about zinnias, the clearer it was they are under-valued.

zinnias, genus Zinnia

The genus Zinnia is from the New World. There are about 17 species, 4 native to North America, most in subtropical America, though one species goes south into Argentina. Many are drought-tolerant species of dry plains. 

Zinnias were discovered by early explorers in the Americas and quickly spread around the world. Common zinnia, Zinnia violacea or Zinnia elegans, also called elegant zinnia and youth-and-old-age, is native to Mexico and was first collected by Europeans in 1789. Carried to Europe, it quickly became a garden favorite. Breeding produced the popular double flowers, and colors from whites and yellows through pinks and reds. Cultivars range in size from 6" tall to over 4'. It has naturalized all over the world including North America. The Flora of North America and the USDA Plants Database both give Zinnia violacea as the scientific name for common zinnia, replacing Zinnia elegans. Apparently the same plant was named twice and Zinnia violaea was first. Almost none of my books or the sellers online have learned of that change at the time of this writing. Wikipedia says Z. violacea is a synonym of Z. elegans. That's backward. Botanically synonym is not an equal name but a name that has been superceded.

common zinnia, double, Zinnia elegans

The genus was named by Linneaus in the middle 1700s for the famous Göttingen botanist and doctor, Johann Gottfried Zinn (1727-1759), who particularly studied the plants being brought to Europe from Mexico. The species epithets of the zinnias mentioned in this post are the following: acerosa meaning needle-shaped, referring to the leaves, while angustifolia means narrow-leaved, anomala means anomalous, elegans means elegant, grandiflora means large-flowered, violacea means purple, and Peruviana means of Peru.

A second Zinnia species that is common in gardens is Zinnia angustifolia, creeping zinnia, also called Mexican zinnia, narrow leaf zinnia, youth and old age, and youth on age, a rather small species from northern and western Mexico. (Today, as a result of 250 years of plant breeding, dwarf common zinnias are often the same size as creeping zinnias). Manycreeping zinnias are pink but varieties also come in white, yellow, and orange, singles to doubles.

garden zinnias

North America has four native zinnias. None of the zinnias are very frost-tolerant, so from midcontinent north, they have to be grown as annuals. All but shortray zinnia are available to gardeners, although searches mostly bring up common zinnia cultivars. 

Two I don't know: 

Shortray zinnia, Zinnia anomala, is endemic to Texas. It has orange or yellow flowers and stands only 6-8" tall. (photos)

Desert zinnia, also called shrubby zinnia and southern zinnia, wild zinnia, and white zinna  Zinnnia acerosa grows in the southwest. The flowers are white. In its native range it is perennial, forming an attractive small mound.(photos)

Peruvian zinnia, Zinnia peruviana, reaches the northern edge of its very large range in Arizona. This was the first zinnia taken to Europe and it was named by Linnaeus. Widely planted, it has naturalized Florida, Georgia, and North and South Carolina. Wild Peruvian zinnias are  reddish, looking like like small Mexican sunflowers (Tithonia), if you know that flower. Most cultivars are red or reddish.

zinnias, probably Peruvian zinnia, Zinnia peruviana

Plains zinnias are also called Rocky Mountain zinnias, golden eye, little golden zinnia, prairie zinnia. wild zinnia and yellow zinnia (Zinnia grandiflora).  They are native from Texas to Kansas west to Colorado and New Mexico, and south into Mexico. Rocky Mountain zinnia is not a particularly good common name because the plants only reach 7000' in the mountains and are much more characteristic of the plains. Not one of my 7  books on "Rocky Mountain plants" included a zinnia. The yellow flower heads are wonderfully showy.

Probably but not certainly, the yellow flowers are plains zinnias,  
Zinnia grandiflorahere growing in New Mexico grasslands

Zinnias do not appear in any of my herbal medicine books from Central and South America and I can find no uses by North American settlers. The range of native zinnias in North America means only tribes of the Southwest had access to them. Desert zinnia was used by the Western Keres as part of a paste to reduce swellings and plants were fed to children to speed them in learning to talk. Plains zinnias have been used more, by the Western Keres, Ramah Navajo, and Zuni. An infusion of plains zinnias treated kidney problems. In a bath (a big dilute infusion) plains zinnias were used to reduce excessive sweating. Or one took a decoction of plains zinnia for stomach ache or heartburn, and as a purgative. A cold infusion of the flowers made an eye rinse. 

The bright flowers of plains zinnias contain dye. Western Keres created a dark red body paint from plains zinnias, ground the flowers in white clay or warm water as a yellow dye for wool, and rubbed the flowers onto buckskin to dye it yellow. 

I can find no reports of butteflies or moths using zinnias as a host plant for their caterpillars. Since they are native wildflowers that are common in some places, most likely the insects that feed on them have not been reported.

Zinnias are very attractive to adult butterflies and often appear in lists of plants for a butterfly garden.  In studies of other plants, researchers have found that the added petals of doubles block access to nectar, but an experiment comparing the attraction of butterflies to four zinnia varieties in Kentucky found Zinnia elegans 'Lilliput ' preferred in thousands of observations; 'Lilliput' appears to be a double. Zinnias, wild and cultivated, are rich in nectar that attracts lots of bees, flies and beetles as well as butterflies. 

Miscellaneous zinnia photos,  cultivated species

A group of bright, easily grown native wildflowers that are beloved by butterflies. 

Comments and corrections welcome.

References

iNaturalist. Elegant zinnia, Zinnia elegans. link Accessed 8/2/24. 

Ladybird Johnson Wildflower Center. Zinnia acerosa link Accessed 8/3/24. 

Ladybird Johnson Wildflower Center. Zinnia anomala link Accessed 8/3/24. 

McKenney, C. B., A. Bates and K. Decker. 2012. 'Raider Gold' plains zinnia (Zinnia grandiflora Nutt.) HortScience 47 (12):1801-1802.

Missouri Plant Finder. Missouri Botanical Garden Zinnia elegans link  Accessed 8/1/24. 

Moerman, D. E. Native American Ethnobotany. link  Accessed 8/3/24.

North Carolina Extension Gardener Plant Toolbox. Zinnia angustifolia link Accessed 8/1/24. 

North Carolina Extension Gardener Plant Toolbox. Zinnia elegans link Accessed 8/1/24. 

North Carolina Extension Gardener Plant Toolbox. Zinnia grandiflora link Accessed 8/1/24. 

North Carolina Extension Gardener Plant Toolbox. Zinnia peruviana link Accessed 8/1/24. 

Smith, A.R. 2020. Zinnia Linnaeus. Flora of North America online link Accessed 8/1/24. 

Surti, D. B. 1956 Zinnia elegans: a fascination to gardeing world. Indianjournals online  link Accessed 8/1/24. 

Yeargan, K.V. and S. M. Colvin. 2009. Butterfly feeding preferences for four zinnia cultivars. J. Environ. Hort (27 (1): 37-41. link  Accessed 8/1/24. 

Kathy Keeler

A Wandering Botanist

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