Gomphrenoideae

The Gomphrenoideae are a subfamily of the Amaranthaceae.

Gomphrenoideae
Gomphrena globosa
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Order:	Caryophyllales
Family:	Amaranthaceae
Subfamily:	Gomphrenoideae Schinz
Genera
about 13 genera, see text

The stamens have anthers with only one lobe (locule) and two pollen sacs. Many species show C₄-photosynthesis pathway.^[1]

The center of diversity lies in Central America, Mexico and the dry forests and thorn bush savannas of South America.^[2]

Systematics

The subfamily Gomphrenoideae was first published in 1893 by Hans Schinz (in: Engler und Prantl (Eds.): Die Natürlichen Pflanzenfamilien vol. 3, 1a, p. 97).

According to phylogenetic research by Sanchez Del-Pino (2009), the subfamily Gomphrenoideae Schinz is regarded as a monophyletic taxon with 19 genera and about 300-400 species. The traditional classification with two tribes (Gomphreneae and Pseudoplantageae) does not reflect the phylogenetic relationship in this group. Three clades can be recognized.:^[1]

Iresinoids

• Irenella Suess., with only one species:
  • Irenella chrysotricha Suess., in rain forests of Ecuador. Phylogenetically, it falls within Iresine.
• Iresine P.Browne (Syn.: Dicraurus Hook. f.): with about 45 species in North and South America.
• Woehleria Griseb.: with only one species
  • Woehleria serpyllifolia Griseb., on mountain coasts of Cuba. Phylogenetically, it falls within Iresine.

This is the sister clade of the two other clades.

Alternantheroids

• Alternanthera Forssk. (Syn.: Brandesia Mart.): with about 100-200 species, mainly in America, also in Africa and Australia.
• Pedersenia Holub: with about 10 species in tropical America.
• Tidestromia Standl.: with about 6 species in deserts of southern North America.

C₄ carbon fixation evolved independently in the genera Alternathera, which also contains C₃ and C₃–C₄ intermediate species, and Tidestromia.^[3][4]

Gomphrenoids

• Blutaparon Raf. (Syn.: Philoxerus R.Br.): with about 5 species at shores of North and Middle America, West Africa, Micronesia and Japan, for example:
  • Blutaparon rigidum
• Froelichia Moench: with about 12 species in America.
• Froelichiella R.E.Fr., with only one species:
  • Froelichiella grisea R.E.Fr. in Brasília.
• Gomphrena L. (Syn.: Bragantia Vand.): with about 90 species in America and about 30 species in Australia. This genus is polyphyletic, so taxonomical changes have to be expected.^[1]
  • Gomphrena pulchella
  • Gomphrena decumbens
  • Gomphrena globosa
• Gossypianthus Hook.: with 2 species in southern North America.
• Guilleminea Kunth (Syn.: Brayulinea Small)
• Hebanthe Mart.: with about 7 species in tropical America.
• Hebanthodes Pedersen, with only one species:
  • Hebanthodes peruviana Pedersen in Peru.
• Lithophila Sw., with 2 species on Galapagos and the Caribic
• Pfaffia Mart.: with about 35 species in tropical America.
• Pseudogomphrena R.E.Fr.,with only one species:
  • Pseudogomphrena scandens R.E.Fr. in Brasília.
• Pseudoplantago Suess.: with one species in Venezuela and one in Argentina.
• Quaternella Pedersen: with 3 species in Brasília.
• Xerosiphon Turcz.: with about 2 species in Brasília.

One large clade within this group, containing the genera Froelichia, Guilleminea, Blutaparon, some Gomphrena species, and probably Gossypianthus and Lithophila, has acquired the C₄ carbon fixation pathway.^[3][4] Some of these C₄ species occur at unusually high altitudes in the Andes, in cooler conditions than their C₃ relatives.^[5]

Photographs

• 
  Iresinoids:
  Iresine lindenii
• 
  Alternantheroids: Alternanthera caracasana
• 
  Alternantheroids:
  Tidestromia lanuginosa
• 
  Gomphrenoids: Gomphrena serrata
• 
  Gomphrenoids:
  Pfaffia glomerata