References

For Hexasepalum

Bacigalupo, N.M., and E.L. Cabral. 1999. Revisión de las especies americanas del género Diodia (Rubiaceae, Spermacoceae). Darwiniana 37: 153-165. Google Scholar

Cabaña Fader, A.A., E. Bezerra de Souza, E.K. de Sousa Brandão, and E.L. Cabral. 2019. Hexasepalum nordestinum (Rubiaceae): A new species from two disjoint and fragmented areas in northeast Brazil, with a key to the American species of the genus. Syst. Bot. 44: 203-209. Google Scholar

Kirkbride, J.H., Jr., and P.G. Delprete. 2015. New combinations in Hexasepalum (Rubiaceae: Spermacoceae). J. Bot Res. Inst. Texas 9: 103-106. Google Scholar

Rogers, G.K. 2005. The genera of Rubiaceae in the southeastern United States, part II. Subfamily Rubioideae, and subfamily Cinchonoideae revisited (Chiococca, Erithalis, and Guettarda). Harvard Papers in Botany 10: 1-45. Google Scholar