Plant of the Week
Latin: Tithonia rotundifolia
As summer wears on, members of the daisy family become more important in our gardens. This happenstance is good for the butterflies because the large blooms of the daisy tribe make good perches and nectar sources for these winged delights.
One plant that really stands out in the late summer garden is Mexican sunflower, Tithonia rotundifolia.
Mexican sunflowers are large, coarse textured annuals capable of reaching 6 feet tall with a spread of half that. They produce stout, branched stems covered by broad, spade-shaped leaves growing 6 to 8 inches long. The leaves are covered with bristly fuzz, perhaps contributing to the deer-proof nature of the plant.
In the typical form, Mexican sunflower has a rangy habit that make it best suited for the back of the border. 'Torch' is the most popular of the larger selections. 'Fiesta del Sol' is a dwarf form growing about 30 inches tall that was an All-American Annual winner in 2000 and is easier to use in smaller gardens.
The bright orange flowers of Mexican sunflower are borne atop the foliage on long, hollow peduncles. The flowers are to 3 inches across with a single array of ray flowers surrounding a dense cluster of bright yellow disc florets. Blooms remain open and attractive for ten days or more, making it an effective cut flower.
The genus Tithonia was described by a French botanist in 1799 with the name taken from Greek mythology. Tithonus was a much-loved by Aurora, the dawn-goddess. The Mexican sunflower is native to Mexico.
Butterflies are general feeders that seek out about any flower that will provide them with sweet, energy-rich nectar. During the hot, dry days of August large flowered wildflowers of the sunflower tribe like true sunflowers, compass plant, cup plant and garden flowers such as Mexican sunflower are important food sources.
But, just because you have a food supply for the butterfly is no guarantee you will continue to have them in your garden. Egg laying and growth of the caterpillar is quite specific. Monarchs need milkweeds as a food plant for the caterpillars; the black swallowtail requires a member of the carrot family like parsley or fennel; the pipevine swallowtail caterpillar feeds only on our native pipevine.
Mexican sunflower is an easy to grow annual. It can be seeded in place in late spring after the danger of frost is past or transplants can be found at local nurseries. It grows best in fertile, well drained sites in full sun. Deadheading during the summer keeps it in bloom through most of the season. Though not immune from insect attack, it has no serious pest problems.
By: Gerald Klingaman, retired
Extension Horticulturist - Ornamentals
Extension News - September 22, 2006
The University of Arkansas Division of Agriculture does not maintain lists of retail outlets where these plants can be purchased. Please check your local nursery or other retail outlets to ask about the availability of these plants for your growing area.