References:

1. Chen, C.-H. & J.-C. Wang. 1999. Revision of the genus Gentiana L. (Gentianaceae) in Taiwan. Bot. Bull. Acad. Sin. 40:9-38.
2. Chen, S.-Y. et al. 2005. Molecular systematics and biogeography of Crawfurdia, Metagentiana and Tripterospermum (Gentianaceae) based on nuclear ribosomal and plastid DNA sequences. Ann. Bot. (Oxford) 96:413-424. Note: study suggests that Crawfurdia, Metagentiana and Tripterospermum form a monophyletic group as sister group to Gentiana
3. Favre, A. et al. 2014. Two new genera of Gentianinae (Gentianaceae): Sinogentiana and Kuepferia supported by molecular phylogenetic evidence. Taxon 63:342-354 DOI: 10.12705/632.5
4. International Society for Horticultural Science. International Cultivar Registration Authority (on-line resource). Note: http://www.ishs.org/sci/icralist/61.htm

Synonyms (=), probable synonyms (=~), and possible synonyms (~):

• (=) Calathiana Delarbre
  (=) Chondrophylla A. Nelson
  (=) Ciminalis Adans.
  (=~) Dasystephana Adans.
  (=) Ericala Gray, orth. var.
  (=) Eurythalia D. Don, orth. var.
  (=) Favargera Á. Löve & D. Löve
  (=~) Gentianodes Á. Löve & D. Löve
  (=) Holubogentia Á. Löve & D. Löve
  (=) Kuepferella M. Laínz
  (~) Kuepferia Adr. Favre
  (=~) Kurramiana Omer & Qaiser
  (=) Mehraea Á. Löve & D. Löve
  (=) Pneumonanthe Gled.
  (=) Qaisera Omer
  (~) Sinogentiana Adr. Favre & Y. M. Yuan
  (=) Tretorhiza Adans.
  (=) Ulostoma G. Don
  

Images:

• Seed: U.S. National Seed Herbarium image