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For the earthworm genus, see Simsia (annelid).

Simsia calva.jpg
Simsia calva
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Asterales
Family: Asteraceae
Subfamily: Asteroideae
Tribe: Heliantheae[1]
Genus: Simsia
Pers. 1807,[2] not R. Br. 1810 (Proteaceae)[3]
Type species
Simsia amplexicaulis[4][5]
  • Encelia sect. Simsia (Pers.) A.Gray
  • Barrattia A.Gray & Engelm. ex A.Gray

Simsia is a genus of flowering plants in the sunflower tribe within the daisy family.[4][6] It includes annuals, herbaceous perennials, and shrubs. They range from the western United States south through Central and South America to Argentina, with the center of diversity occurring in Mexico. The genus is named for British physician and botanist John Sims (1749–1831).[7] 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 Asteraceae. Some species are known by the common name bushsunflower.[8]

Description and systematics[edit]

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). 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.[7]

The genus was thoroughly studied by Spooner[9] using comparative morphology, chromosome counts, and crossing experiments, and based on samples from wide-ranging field work. Subsequently two new species have been documented,[10] 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, it is now firmly established that Simsia is part of subtribe Helianthinae (the taxonomic group which includes the common sunflower, Helianthus annuus), and is a close relative of Tithonia[7][11]

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.[5]

  1. Simsia amplexicaulis (Cav.) Pers. - Guatemala, Honduras, Mexico (from Chihuahua to Chiapas)
  2. Simsia annectens S.F.Blake - Chiapas, Michoacán, Oaxaca, Guerrero, México State, Jalisco, Nayarit
  3. Simsia calva (A.Gray) A.Gray – Awnless bush sunflower[14] - Nuevo León, Coahuila, Hidalgo, Tamaulipas, United States (TX NM)
  4. Simsia caucana Cuatrec. - Cauca in Colombia
  5. Simsia chaseae (Millspaugh) S.F.Blake - Veracruz, Yucatán Peninsula
  6. Simsia dombeyana (A.Gray) S.F.Blake - Venezuela, Ecuador, Peru, Brazil, Bolivia, Paraguay, Argentina
  7. Simsia eurylepis S.F.Blake - San Luis Potosí, Tamaulipas, Veracruz, Campeche, Nuevo León
  8. Simsia foetida (Cav.) S.F.Blake[15] - from Michoacán to Nicaragua
  9. Simsia fruticulosa (Sprengel) S.F.Blake - Colombia, Venezuela, Ecuador
  10. Simsia ghiesbreghtii (A.Gray) S.F.Blake - Chiapas, Guatemala
  11. Simsia grandiflora Benth. ex Oerst. - Nicaragua, Honduras, El Salvador, Guatemala, Chiapas
  12. Simsia guatemalensis H.Rob. & Brettell - Honduras, El Salvador, Guatemala
  13. Simsia hispida (Kunth) Cass. - San Luis Potosí, Michoacán, México State
  14. Simsia holwayi S.F.Blake - Guatemala, Chiapas
  15. Simsia jamaicensis S.F.Blake - Jamaica
  16. Simsia lagascaeformis DC. – Annual bush sunflower[14] - Mexico, Guatemala, United States (AZ TX NM)
  17. Simsia molinae H.Rob. & Brettell - Honduras, Nicaragua
  18. Simsia pastoensis Triana - Colombia
  19. Simsia sanguinea A.Gray - El Salvador, Guatemala, Chiapas, Oaxaca, Puebla, Veracruz, Michoacán, Morelos, México State, Jalisco
  20. Simsia santarosensis Spooner - Costa Rica
  21. Simsia setosa S.F.Blake - Sonora, Durango, Nayarit
  22. Simsia steyermarkii H.Rob. & Brettell - Guatemala
  23. Simsia subaristata A.Gray - Nuevo León
  24. Simsia tenuis (Fernald) S.F.Blake - Guerrero
  25. Simsia villasenorii Spooner - Chiapas, Oaxaca
Formerly included[1]

numerous species now regarded as members of other genera: Encelia Geraea Iostephane Viguiera


  1. ^ a b c d Flann, C (ed) 2009+ Global Compositae Checklist Archived 2014-11-06 at
  2. ^ "Genus: Simsia Pers". Germplasm Resources Information Network. United States Department of Agriculture. 1996-09-17. Retrieved 2011-02-13.
  3. ^ Tropicos, Simsia R. Br.
  4. ^ a b Tropicos, Simsia Pers.
  5. ^ a b Robinson, Harold Ernest & Brettell, R. D. 1972. Phytologia 24(5): 361-377
  6. ^ Persoon, Christiaan Hendrik. 1807. Synopsis Plantarum 2: 478-479 in Latin
  7. ^ a b c Spooner, David M. "Simsia Persoon, Syn. Pl. 2: 478. 1807". Flora of North America. Retrieved 2011-12-30.
  8. ^ "Simsia". Natural Resources Conservation Service PLANTS Database. USDA. Retrieved 15 November 2015.
  9. ^ Spooner, D. M. 1990. Systematics of Simsia (Compositae-Heliantheae). Systematic Botany Monographs 30: 1-90.
  10. ^ Panero, J. L.; E. E. Schilling (1992). "Two new species of Simsia from southern Mexico". Novon. 2: 35–38. doi:10.2307/3391498.
  11. ^ Schilling, E. E.; J. L. Panero (1996). "Phylogenetic reticulation in subtribe Helianthinae". American Journal of Botany. 83: 939–948. doi:10.2307/2446272.
  12. ^ The Plant List search for Simsia
  13. ^ Biota of North America Program 2013 county distribution maps
  14. ^ a b "Simsia". Integrated Taxonomic Information System. Retrieved 2011-02-13.
  15. ^ "GRIN Species Records of Simsia". Germplasm Resources Information Network. United States Department of Agriculture. Retrieved 2011-02-13.