''Tithonia rotundifolia'', the red sunflower or Mexican sunflower, is a plant in the family

Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

, which is native to the warmer and moister parts of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

Description

Monarch butterfly flying away from a Mexican sunflower

Plants are perennial in the native habitat, up to 4 m tall with orange or red flowers (in cultivation only 0.8 to 1.5 meters). In

USDA zone A hardiness zone is a geographic area defined as having a certain average annual minimum temperature, a factor relevant to the survival of many plants. In some systems other statistics are included in the calculations. The original and most widely ...

s cooler than Zone 10 it is an annual. Leaves, despite the epithet, are deltoid to lanceolate, occasionally lobed (or broadly heart-shaped) up to 38 cm long and 30 cm wide, with subentire, crenate or serrated margin. The lower ones are usually three-lobed. The

petiole Petiole may refer to: *Petiole (botany), the stalk of a leaf, attaching the blade to the stem *Petiole (insect anatomy) In entomology, petiole is the technical term for the narrow waist of some hymenopteran insects, especially ants, bees, and ...

is up to 40 centimeters long. The upper side of the leaves is gray, the underside is hairy.

Inflorescence

The

flower head A pseudanthium (; : pseudanthia) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, composite flowers ...

s have a diameter of 5 to 8 (rarely up to 10) centimeters. The ray flowers are vermilion red and broadly egg-shaped. The disc flowers are golden yellow and are generally solitary, long-pedunculated head, with a

campanulate This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary ...

to hemispherical

involucrum An involucrum (plural involucra) is a layer of new bone growth outside existing bone. There are two main contexts: * In pyogenic osteomyelitis where it is a layer of living bone that has formed around dead bone. It can be identified by radiogr ...

. There are 12 to 16 bracts, the outer ones being pointed. The flowers are used by many insects as a nectar source including migrating monarch butterflies. The fruit is a turbinado-quadrangular cypsel less than 1 cm long, brown or black, with two unequal deciduous wings.

Range

It occurs in

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

Louisiana Louisiana ( ; ; ) is a state in the Deep South and South Central regions of the United States. It borders Texas to the west, Arkansas to the north, and Mississippi to the east. Of the 50 U.S. states, it ranks 31st in area and 25 ...

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

, and the

West Indies The West Indies is an island subregion of the Americas, surrounded by the Atlantic Ocean, North Atlantic Ocean and the Caribbean Sea, which comprises 13 independent island country, island countries and 19 dependent territory, dependencies in thr ...

on fields, in woody plants and

ruderal A ruderal species is a plant species that is first to colonize disturbed lands. The disturbance may be natural for example, wildfires or avalanchesor the consequences of human activities, such as construction ( of roads, of buildings, mining, e ...

ly at altitudes below 1000 meters on the edges of roads and highways, as well as in other disturbed areas. Outside its native region it is sometimes grown as an ornamental and has become naturalized in some of these locales. In Africa it has been recorded up to an altitude of 1,580 m above sea level.

Cultivation

Due to its characteristics, it is usually used in

hedge A hedge or hedgerow is a line of closely spaced (3 feet or closer) shrubs and sometimes trees, planted and trained to form a barrier or to mark the boundary of an area, such as between neighbouring properties. Hedges that are used to separate ...

s to form a background for other smaller plants. It requires poor to average, well-drained soil in an area protected from the wind to prevent its brittle stems from bending or breaking. It is propagated from seeds. Seedlings are planted 30–50 centimeters apart. It requires a sunny plant site and fresh, nutrient-rich soil with plenty of

humus In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Lati ...

. It tolerates drought well, but it still needs water during long periods of drought. Tithonia usually blooms from summer until the first frosts.

Gallery

Tithonia rotundifolia Covered In the First Snow of Fall in Zone 5a.jpg, The plant covered in the first snow of fall in zone 5a Tithonia rotundifolia mexican sunflower.JPG Tithonia rotundifolia (1217996568).jpg Mexican Sunflower Tithonia rotundifolia Plants 3008px.jpg Starr-090803-3643-Tithonia rotundifolia-flower and leaves-Wailuku-Maui (24877745931).jpg Tithonia rotundifolia with butterfly 4835.jpg Starr-090803-3642-Tithonia rotundifolia-flower and leaves-Wailuku-Maui (24944757296).jpg Redflower1.jpg

Synonyms

*''Tithonia rotundifolia'' (Mill.) S.F. Blake, Contr. Gray Herb. 52: 41. 1917. **''Tagetes rotundifolia'' Miller, Gard. Dict. ed. 8, Tagetes no. 4. 1768. **''Helianthus speciosus'' Hook., Bot. Mag. 61: t. 3295. 1834. **''Tithonia speciosa'' (Hook.) Griseb., Cat. pl. Cub. 155. 1866. **''Tithonia vilmoriniana'' Pamp.Tithonia vilmoriniana Pamp.
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References

{{Taxonbar, from=Q2176037 Heliantheae Flora of Mexico Garden plants of Central America Flora of Florida Flora of Louisiana Flora of Central America Flora of Cuba Flora without expected TNC conservation status