''Simsia'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s in the tribe

Heliantheae The Heliantheae (sometimes called the sunflower tribe) are the third-largest Tribe (biology), tribe in the sunflower family (Asteraceae). With some 190 genera and nearly 2500 recognized species, only the tribes Senecioneae and Astereae are large ...

within 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 ...

.Tropicos, ''Simsia'' Pers.
/ref> It includes annuals,

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...

perennials In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

, and

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

s. They range from the

western United States The Western United States (also called the American West, the Western States, the Far West, the Western territories, and the West) is List of regions of the United States, census regions United States Census Bureau. As American settlement i ...

south through Central and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

, with the center of diversity occurring in Mexico. The genus is named for British physician and botanist John Sims (1749–1831). Although some species are relatively rare, others have become common weeds that line the roadsides and fields of Mexico, often forming dense stands mixed with '' Tithonia'' and other

. Some species are known by the common name bushsunflower.

Description and systematics

A feature that characterizes many of the species of the genus and helps to distinguish them from related genera is the extremely flattened cypsela (

achene An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple fruit, simple dry fruits, dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and Dehi ...

). There are, however, several species in which the cypsela is biconvex, and these are recognized as belonging to ''Simsia'' by a group of other, mostly technical features, including nodal disks (stipule-like appendages at the base of the petioles), relatively long and narrow ray ovaries, and long and tapering style branches that lack a pronounced apical appendage. The genus was thoroughly studied by Spooner using comparative morphology, chromosome counts, and crossing experiments, and based on samples from wide-ranging field work. Subsequently two new species have been documented, and additional species are being transferred into the genus. Although at one time, ''Simsia'' was considered to be related to other genera with flattened cypselae, such as ''

Encelia ''Encelia'' is a genus of the Family (biology), plant family Asteraceae whose members are frequently called brittlebushes. It consists of shrubs (and one geophyte) of arid environments in southwestern North America and western South America. Al ...

'', it is now firmly established that ''Simsia'' is part of subtribe Helianthinae (the taxonomic group which includes the common sunflower, ''

Helianthus annuus The common sunflower (''Helianthus annuus'') is a species of large annual forb of the daisy family Asteraceae. The common sunflower is harvested for its edible oily seeds, which are often eaten as a snack food. They are also used in the pro ...

''), and is a close relative of ''Tithonia'' All of the species for which chromosome counts have been made are diploid (''x'' = 17), and crossing experiments suggest that there are few barriers to hybridization between species of the genus. Natural hybridization appears to occur and may complicate identification of some specimens, particularly involving the weedy species such as ''S. foetida'', ''S. amplexicaulis'', and ''S. lagascaeformis''. ; SpeciesFlann, C (ed) 2009+ Global Compositae Checklist
Biota of North America Program 2013 county distribution maps
/ref> * '' Simsia amplexicaulis'' (Cav.) Pers. -

Guatemala Guatemala, officially the Republic of Guatemala, is a country in Central America. It is bordered to the north and west by Mexico, to the northeast by Belize, to the east by Honduras, and to the southeast by El Salvador. It is hydrologically b ...

Honduras Honduras, officially the Republic of Honduras, is a country in Central America. It is bordered to the west by Guatemala, to the southwest by El Salvador, to the southeast by Nicaragua, to the south by the Pacific Ocean at the Gulf of Fonseca, ...

, Mexico (from Chihuahua to

Chiapas Chiapas, officially the Free and Sovereign State of Chiapas, is one of the states that make up the Political divisions of Mexico, 32 federal entities of Mexico. It comprises Municipalities of Chiapas, 124 municipalities and its capital and large ...

) * '' Simsia annectens'' S.F.Blake -

Michoacán Michoacán, formally Michoacán de Ocampo, officially the Free and Sovereign State of Michoacán de Ocampo, is one of the 31 states which, together with Mexico City, compose the Political divisions of Mexico, Federal Entities of Mexico. The stat ...

Oaxaca Oaxaca, officially the Free and Sovereign State of Oaxaca, is one of the 32 states that compose the political divisions of Mexico, Federative Entities of the Mexico, United Mexican States. It is divided into municipalities of Oaxaca, 570 munici ...

Guerrero Guerrero, officially the Free and Sovereign State of Guerrero, is one of the 32 states that compose the administrative divisions of Mexico, 32 Federal Entities of Mexico. It is divided into Municipalities of Guerrero, 85 municipalities. The stat ...

México State The State of Mexico, officially just Mexico, is one of the 32 federal entities of the United Mexican States. Colloquially known as Edomex (from , the abbreviation of , and ), to distinguish it from the name of the whole country, it is the mos ...

Jalisco Jalisco, officially the Free and Sovereign State of Jalisco, is one of the 31 states which, along with Mexico City, comprise the 32 Political divisions of Mexico, Federal Entities of Mexico. It is located in western Mexico and is bordered by s ...

Nayarit Nayarit, officially the Free and Sovereign State of Nayarit, is one of the 31 states that, along with Mexico City, comprise the Political divisions of Mexico, Federal Entities of Mexico. It is divided in Municipalities of Nayarit, 20 municipalit ...

* '' Simsia calva'' (A.Gray) A.Gray – Awnless bush sunflower -

Nuevo León Nuevo León, officially the Free and Sovereign State of Nuevo León, is a Administrative divisions of Mexico, state in northeastern Mexico. The state borders the Mexican states of Tamaulipas, Coahuila, Zacatecas, and San Luis Potosí, San Luis ...

Coahuila Coahuila, formally Coahuila de Zaragoza, officially the Free and Sovereign State of Coahuila de Zaragoza, is one of the 31 states of Mexico. The largest city and State Capital is the city of Saltillo; the second largest is Torreón and the thi ...

Hidalgo Hidalgo may refer to: People * Hidalgo (nobility), members of the Spanish nobility * Hidalgo (surname) Places Mexico :''Most, if not all, named for Miguel Hidalgo y Costilla (1753–1811)'' * Hidalgo (state), in central Mexico * Hidalgo, Coah ...

Tamaulipas Tamaulipas, officially the Free and Sovereign State of Tamaulipas, is a state in Mexico; one of the 31 states which, along with Mexico City, comprise the 32 federal entities of Mexico. It is divided into 43 municipalities. It is located in nor ...

, United States ( TX NM) * '' Simsia caucana'' Cuatrec. - Cauca in

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

* '' Simsia chaseae'' (Millspaugh) S.F.Blake -

Veracruz Veracruz, formally Veracruz de Ignacio de la Llave, officially the Free and Sovereign State of Veracruz de Ignacio de la Llave, is one of the 31 states which, along with Mexico City, comprise the 32 Political divisions of Mexico, Federal Entit ...

Yucatán Peninsula The Yucatán Peninsula ( , ; ) is a large peninsula in southeast Mexico and adjacent portions of Belize and Guatemala. The peninsula extends towards the northeast, separating the Gulf of Mexico to the north and west of the peninsula from the C ...

* '' Simsia dombeyana'' (A.Gray) S.F.Blake -

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli ...

* '' Simsia eurylepis'' S.F.Blake -

San Luis Potosí San Luis Potosí, officially the Free and Sovereign State of San Luis Potosí, is one of the 32 states which compose the Federal Entities of Mexico. It is divided in 59 municipalities and is named after its capital city, San Luis Potosí. It ...

Campeche Campeche, officially the Free and Sovereign State of Campeche, is one of the 31 states which, with Mexico City, make up the Administrative divisions of Mexico, 32 federal entities of Mexico. Located in southeast Mexico, it is bordered by the sta ...

* '' Simsia foetida'' (Cav.) S.F.Blake - from

Nicaragua Nicaragua, officially the Republic of Nicaragua, is the geographically largest Sovereign state, country in Central America, comprising . With a population of 7,142,529 as of 2024, it is the third-most populous country in Central America aft ...

* '' Simsia fruticulosa'' (Sprengel) S.F.Blake -

* '' Simsia ghiesbreghtii'' (A.Gray) S.F.Blake -

* '' Simsia grandiflora'' Benth. ex Oerst. -

El Salvador El Salvador, officially the Republic of El Salvador, is a country in Central America. It is bordered on the northeast by Honduras, on the northwest by Guatemala, and on the south by the Pacific Ocean. El Salvador's capital and largest city is S ...

* '' Simsia guatemalensis'' H.Rob. & Brettell -

* '' Simsia hispida'' (Kunth) Cass. -

* '' Simsia holwayi'' S.F.Blake -

* '' Simsia jamaicensis'' S.F.Blake -

Jamaica Jamaica is an island country in the Caribbean Sea and the West Indies. At , it is the third-largest island—after Cuba and Hispaniola—of the Greater Antilles and the Caribbean. Jamaica lies about south of Cuba, west of Hispaniola (the is ...

* '' Simsia lagasceiformis'' DC. – Annual bush sunflower - Mexico,

, United States ( AZ TX NM) * '' Simsia molinae'' H.Rob. & Brettell -

* '' Simsia pastoensis'' Triana -

* '' Simsia sanguinea'' A.Gray -

Puebla Puebla, officially the Free and Sovereign State of Puebla, is one of the 31 states that, along with Mexico City, comprise the Federal Entities of Mexico. It is divided into 217 municipalities and its capital is Puebla City. Part of east-centr ...

Morelos Morelos, officially the Free and Sovereign State of Morelos, is a landlocked state located in south-central Mexico. It is one of the 32 states which comprise the Political divisions of Mexico, Federal Entities of Mexico. It is divided into Mun ...

* '' Simsia santarosensis'' Spooner -

Costa Rica Costa Rica, officially the Republic of Costa Rica, is a country in Central America. It borders Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, and the Pacific Ocean to the southwest, as well as Maritime bo ...

* '' Simsia setosa'' S.F.Blake -

Sonora Sonora (), officially Estado Libre y Soberano de Sonora (), is one of the 31 states which, along with Mexico City, comprise the Administrative divisions of Mexico, Federal Entities of Mexico. The state is divided into Municipalities of Sonora, 72 ...

Durango Durango, officially the Free and Sovereign State of Durango, is one of the 31 states which make up the Political divisions of Mexico, 32 Federal Entities of Mexico, situated in the northwest portion of the country. With a population of 1,832,650 ...

* '' Simsia steyermarkii'' H.Rob. & Brettell -

* '' Simsia subaristata'' A.Gray -

* '' Simsia tenuis'' (Fernald) S.F.Blake -

* '' Simsia villasenorii'' Spooner -

; Formerly included numerous species now regarded as members of other genera: ''

Geraea ''Geraea'' is a genus of the family Asteraceae from the southwestern United States and northwestern Mexico, commonly called the desert sunflower. ; Species * ''Geraea canescens'' Torr. & A.Gray - California, Arizona, Nevada, Utah * '' Geraea vi ...

Iostephane

Viguiera ''Viguiera'' is a genus of flowering plants in the family Asteraceae. It contains around 19–40 species, which are commonly known as goldeneyes and are native to the New World. These are herbs to bushy shrubs that bear yellow or orange daisy-lik ...

References

* * {{Taxonbar, from=Q4419875 Asteraceae genera Heliantheae Flora of the Americas