Tithonia is a genus of flowering plant

Flowering plant

The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...

s in the family Asteraceae

Asteraceae

The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...

. It includes 11 species, with a center of distribution in Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 but with one species extending into the Southwestern United States

Southwestern United States

The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...

 and several extending into Central America

Central America

Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

. Two species, T. diversifolia

Tithonia diversifolia

Tithonia diversifolia is a species of flowering plant in the Asteraceae family that is commonly known as the tree marigold, Mexican tournesol, Mexican sunflower, Japanese sunflower or Nitobe chrysanthemum. It is native to eastern Mexico and Central America but has a nearly pantropical distribution...

and T. rotundifolia, are widely cultivated and have escaped to become weed

Weed

A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...

s in tropical and subtropical areas around the world. The distinguishing feature of the genus is the peduncle, which is fistulose (meaning hollow and flaring toward the apex). The plants are coarse annual

Annual plant

An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...

 or perennial

Perennial plant

A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...

 herbs

Herbaceous plant

A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...

 or shrub

Shrub

A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

s, and one species, T. koelzii, is a small tree

Tree

A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

.

Species

• Tithonia brachypappa B.L.Rob.
• Tithonia calva Sch.Bip.
  Carl Heinrich Schultz
  Carl Heinrich Schultz was a German physician and botanist, and a brother to Friedrich Wilhelm Schultz ....
  
  
• Tithonia diversifolia
  Tithonia diversifolia
  Tithonia diversifolia is a species of flowering plant in the Asteraceae family that is commonly known as the tree marigold, Mexican tournesol, Mexican sunflower, Japanese sunflower or Nitobe chrysanthemum. It is native to eastern Mexico and Central America but has a nearly pantropical distribution...
  
  (Hemsl.
  William Hemsley (botanist)
  William Botting Hemsley was an English botanist and 1909 Victoria Medal of Honour recipient....
  
  ) A.Gray
  Asa Gray
  -References:*Asa Gray. Dictionary of American Biography. American Council of Learned Societies, 1928–1936.*Asa Gray. Encyclopedia of World Biography, 2nd ed. 17 Vols. Gale Research, 1998.*Asa Gray. Plant Sciences. 4 vols. Macmillan Reference USA, 2001....
  
  – Tree Marigold
• Tithonia fruticosa Canby & Rose
• Tithonia hondurensis La Duke
• Tithonia koelzii McVaugh
• Tithonia longiradiata (Bertol.) S.F.Blake
• Tithonia pedunculata Cronquist
• Tithonia rotundifolia (Mill.
  Philip Miller
  Philip Miller FRS was a Scottish botanist.Miller was chief gardener at the Chelsea Physic Garden from 1722 until he was pressured to retire shortly before his death...
  
  ) S.F.Blake
• Tithonia thurberi Gray – Arizona Sunflower Weed
• Tithonia tubaeformis (Jacq.) Cass.

Formerly placed here

• Enceliopsis argophylla (as T. argophylla)