Andropogoneae Explained

The Andropogoneae, sometimes called the sorghum tribe, are a large tribe of grasses (family Poaceae) with roughly 1,200 species in 90 genera, mainly distributed in tropical and subtropical areas. They include such important crops as maize (corn), sugarcane, and sorghum.^[1] All species in this tribe use C₄ carbon fixation, which makes them competitive under warm, high-light conditions.^[2]

Andropogoneae is classified in supertribe Andropogonodae, together with its sister group Arundinelleae. Subdivisions include 12 subtribes, but the position of several genera within them is still unresolved (incertae sedis). Hybridisation was probably important in the evolution of the Andropogoneae, and the tribe's systematics are still not completely resolved.^[2] From the morphological point of view, the merging of the former subtribe 'Dimeriinae' (having solitary spikelets borne in 'robust' raceme rachis) into the subtribe Ischaeminae (having paired spikelets borne in 'fragile' raceme rachis) is doubtful. Affinities within the tribe are complex and still under investigation. Mr. Shahid Nawaz, a grass specialist at the Blatter Herbarium, is working on the phylogenomics of the tribe from India.

According to preliminary phytogeographic research on the tribe by MS Kiran Raj, Peninsular India, home to 54 genera (incl. 9 endemic genera, viz., Bhidea, Lophopogon, Glyphochloa, Pogonachne, Trilobachne, Pseudodichanthium, Triplopogon, Nanooravia, and Manisuris) and roughly 500 species, is thought to be the primary or secondary centre of diversity for Andropogonoid grasses. About 40% of the representative taxa are exclusively endemic to peninsular India, with the highest species diversity and endemicity found in genera like Arthraxon, Chrysopogon, Cymbopogon, Dichanthium, Dimeria, Heteropogon, Ischaemum, Ophiorus, Sehima, and Themeda.^{[3] [4]}

Description

Spikelets within the inflorescence (flower cluster) are generally arranged on spicate racemes in pairs. A fertile, unstalked spikelet is subtended by a sterile, stalked spikelet. In species where awns are present they are found on the fertile, unstalked spikelet as an extension of the lemma.^[5]

Subtribes and genera

2017 classification

Classification following Soreng et al. (2017):

2020 classification

Classification following Welker et al. (2020) (one asterisk * marks genera not sampled in their analyses that were tentatively placed based on previously published phylogenetic analyses; two asterisks ** marks genera placed solely on morphology):^[6] Tribe Andropogoneae – 14 subtribes, 92 genera, and about 1224 species

• Subtribe Arthraxoninae – 1 genus and about 27 species
  • Arthraxon – 27 species
• Subtribe Tripsacinae – 2 genera and about 23 species
  • Tripsacum – 16 species
  • Zea – 7 species
• Subtribe Chionachninae – 3 genera and about 12 species
  • Chionachne – 9 species
  • Polytoca – 2 species
  • Trilobachne – 1 species **
• Subtribe Rhytachninae – 5 genera and about 26 species
  • Loxodera – 5 species
  • Oxyrhachis – 1 species
  • Rhytachne – 12 species
  • Urelytrum – 7 species
  • Vossia – 1 species
• Subtribe Chrysopogoninae – 1 genus and about 49 species
  • Chrysopogon – 49 species
• Subtribe Rottboelliinae = Coicinae – 3 genera and about 13 species
  • Chasmopodium – 3 species *
  • Coix – 4 species
  • Rottboellia – 6 species
• Subtribe Ratzeburgiinae – 11 genera and about 87 species
  • Eremochloa – 12 species
  • Glyphochloa – 9 species
  • Hackelochloa – 2 species
  • Hemarthria – 14 species
  • Heteropholis – 6 species *
  • Manisuris – 1 species *
  • Mnesithea – 26 species
  • Ophiuros – 4 species *
  • Ratzeburgia – 1 species **
  • Thaumastochloa – 8 species *
  • Thyrsia – 4 species
• Subtribe Ischaeminae = Dimeriinae – 4 genera and about 152 species
  • Andropterum – 1 species
  • Dimeria – 61 species
  • Eulaliopsis – 2 species
  • Ischaemum – 88 species
• Subtribe Germainiinae – 5 genera and about 44 species
  • Apocopis – 16 species *
  • Germainia – 10 species
  • Imperata – 13 species
  • Lophopogon – 2 species **
  • Pogonatherum – 3 species
• Subtribe Sorghinae – 4 genera and about 37 species
  • Cleistachne – 1 species
  • Lasiorhachis – 3 species
  • Sarga – 9 species
  • Sorghum – 24 species
• Subtribe Saccharinae – 3 genera and about 64 species
  • Miscanthus – 30 species
  • Pseudosorghum – 2 species
  • Saccharum – 32 species
• Subtribe Apludinae – 7 genera and about 68 species
  • Apluda – 1 species
  • Asthenochloa – 1 species **
  • Eulalia – 34 species
  • Homozeugos – 6 species
  • Polytrias – 1 species
  • Sorghastrum – 21 species
  • Trachypogon – 4 species
• Subtribe Anthistiriinae – 9 genera and about 204 species
  • Bothriochloa – 37 species
  • Capillipedium – 18 species
  • Cymbopogon – 59 species
  • Dichanthium – 22 species
  • Eremopogon – 4 species *
  • Euclasta – 2 species
  • Heteropogon – 6 species
  • Iseilema – 24 species
  • Themeda – 32 species
• Subtribe Andropogoninae – 11 genera and about 292 species
  • Anadelphia – 14 species
  • Andropogon – 125 species
  • Bhidea – 3 species **
  • Diectomis – 1 species
  • Diheteropogon – 4 species
  • Elymandra – 6 species
  • Exotheca – 1 species
  • Hyparrhenia – 58 species
  • Hyperthelia – 7 species
  • Monocymbium – 3 species
  • Schizachyrium – 70 species
• Incertae sedis – 23 genera and about 126 species
  • Agenium – 4 species *
  • Elionurus – 17 species
  • Eriochrysis – 11 species
  • Jardinea – 3 species
  • Kerriochloa – 1 species
  • Lasiurus – 1 species
  • Leptatherum – 3 species *
  • Microstegium – 27 species
  • Parahyparrhenia – 6 species
  • Phacelurus – 6 species *
  • Pseudopogonatherum – 5 species *
  • Sehima – 5 species
  • Spodiopogon – 18 species *
  • Thelepogon – 2 species
  • Tripidium – 6 species
  • Clausospicula – 1 species **
  • Lakshmia – 1 species **
  • Pogonachne – 1 species **
  • Pseudanthistiria – 4 species **
  • Pseudodichanthium – 1 species **
  • Spathia – 1 species **
  • Triplopogon – 1 species **
  • Veldkampia – 1 species **

Notes and References

1. Also called "kaoliang": "Shensi", in The Columbia-Viking Encyclopedia (1953), New York: Viking. Another spelling is "gaoliang."
2. Soreng . Robert J. . Peterson . Paul M. . Romschenko . Konstantin . Davidse . Gerrit . Zuloaga . Fernando O. . Judziewicz . Emmet J. . Filgueiras . Tarciso S. . Davis . Jerrold I. . Morrone . Osvaldo . A worldwide phylogenetic classification of the Poaceae (Gramineae) . Journal of Systematics and Evolution . 53 . 2 . 2015 . 117–137 . 1674-4918 . 10.1111/jse.12150. 11336/25248 . free .
3. Book: Grass Diversity of Kerala Endemism and its Phytogeographical Significance. In MK Jananrdhanan & D. Narasimhan (Eds.) Plant diversity, Human welfare and conservation. . Raj, Kiran, MS, ((M. Sivadasan and N. Ravi)) . 2003 . Goa University. . 2003 . Goa . 2003 . 8–30.
4. Web site: Kiranraj . MS . 2008 . Taxonomic revision of the subtribe Dimeriinae Hack of Andropogoneae Panicoideae Poaceae in Peninsular India . Shodhganga : a reservoir of Indian theses @ INFLIBNET.
5. Skendzic . Elizabeth . Columbus . J. Travis . Cerros-Tlatilpa . Rosa . 2007 . Phylogenetics of Andropogoneae (Poaceae: Panicoideae) Based on Nuclear Ribosomal Internal Transcribed Spacer and Chloroplast trnL–F Sequences. Aliso: A Journal of Systematic and Evolutionary Botany . 23 . 1 . 530–544 . 10.5642/aliso.20072301.40 . 14 April 2020. free .
6. Welker . Cassiano A. D. . McKain . Michael R. . Estep . Matt C. . Pasquet . Rémy S. . Chipabika . Gilson . Pallangyo . Beatrice . Kellogg . Elizabeth A. . 2020 . Phylogenomics enables biogeographic analysis and a new subtribal classification of Andropogoneae (Poaceae—Panicoideae) . Journal of Systematics and Evolution . 58 . 6 . 1003–1030 . 10.1111/jse.12691 . amp .