''Flaveria trinervia'' is a species of flowering plant in the family

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

known by the

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

s clustered yellowtops, speedyweed, and yellow twinstem. It is native to parts of the Americas, including the southeastern and southwestern United States (

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

), most of the Bahamas, Mexico, Belize, and parts of the

Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...

, especially Cuba, Cayman Islands, Jamaica, Hispaniola, Puerto Rico and Barbados. It is also known in many other places as an

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived there ...

and often a

noxious weed A noxious weed, harmful weed or injurious weed is a weed that has been designated by an agricultural or other governing authority as a plant that is injurious to agricultural or horticultural crops, natural habitats or ecosystems, or humans or liv ...

, such as in

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

. ''Flaveria trinervia'' grows easily in many types of wet habitats, including saline and

alkaline In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a base (chemistry), basic, ionic compound, ionic salt (chemistry), salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as ...

soils and highly disturbed habitat. This is an annual herb growing erect and known to exceed two meters (7 feet) in height. The lance-shaped to oval leaves are each up to 15 centimeters (8 inches) long and arranged oppositely in pairs around the stem, their bases sometimes fused together. The edges of the leaves generally have tiny widely spaced teeth. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

is a large dense cluster of many very small

flower heads A pseudanthium (Greek for "false flower"; ) 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, compos ...

, sometimes over 300 in one cluster. Each flower head contains 0-1 yellow or whitish ray floret and 0-2 yellow disc florets.Powell, Albert Michael. 1979. Annals of the Missouri Botanical Garden 65(2): 628-629
description and commentary in English, distribution map on page 625 This plant exhibits C₄ carbon fixation. The Australian species '' F. australasica'' is very similar and possibly closely related to ''F. trinervia.'' Some authors treat the two as distinct speciesPowell, Albert Michael. 1979. Annals of the Missouri Botanical Garden 65(2): 629-630
description and commentary in English while others consider ''F. australasica'' as a synonym of ''F. trinervia.''Atlas of Living Australia, ''Flaveria trinervia'' (Spreng.) C.Mohr
/ref>

References

External links

Jepson Manual TreatmentUnited States Department of Agriculture Plants Profilephoto of herbarium specimen at Missouri Botanical Garden, collected in Nuevo León in 1848Discover Life
{{Taxonbar, from=Q5458052 trinervia Flora of the Caribbean Flora of Mexico Flora of Belize Flora of the South-Central United States Flora of the Southeastern United States Flora without expected TNC conservation status