Bolivian sunflower is sometimes known as Mexican sunflower, but that common name also applies to another Tithonia species, so to be completely accurate, just call it Tithonia diversifolia
! Some sources also list tree marigold as a common name.
This species grows fast and large, so give it plenty of space in the landscape. Plants can easily grow to 12 feet tall and wide in a single year.
The bright yellow, 6-inch diameter flowers can appear anytime there is active growth, but bloom production peaks in late summer and fall. There is a slight, pleasant fragrance if you put your nose right up to the flower. They need a full sun location for best flower production, but the plants will also tolerate some shade.
The leaves are large, hairy and deeply lobed. They can reach up to a foot in length.
Stems are rough and covered with prominent lenticels.
Stems often form aerial roots. If they bend over and touch the ground, they'll start a new plant.
The inside of the stem is filled with a lightweight, spongy xylem.
This quality makes the cut stems decompose quickly and is why Tithonia diversifolia
is frequently used as a "chop and drop" plant; the chopped leaves and stems can be used as a nutrient-rich mulch or compost. In poor soils, the chopped leaves and stems can be used as an alternative to commercial N-P-K fertilizers. Inter-cropping with Tithonia
has a positive effect on crop yields, provided you prevent it from taking over the other crops.
The base of the plant becomes trunk-like with age.
This species is native to Central America and Mexico, but has spread throughout tropical and subtropical regions world-wide. It is recommended for USDA Zones 9-11, but can be grown as a perennial in Zone 8.
The leaves are suitable fodder for cows and goats, and deer also love to browse on the nutrient-rich leaves.
Propagation is by seed or cuttings. The variety I grow is a sterile cultivar, so there's no worry about it spreading out of control.
An infusion of Tithonia diversifolia
leaves has been used in some folk medicines as a treatment for a wide range of maladies, including diabetes, cholesterol, sore throat and measles. Lab studies
indicate both positive and negative results. Another study
shows promising results as an anti-inflammatory and analgesic. Still other studies
have indicated a potential treatment for malaria and also use as a topical mosquito repellent.