Hyssopus L.
Hyssopus is a complex genus with either one, very variable species (H. officinalis) or up to about 15 hardly distinguishable species (e.g. Borisova 1977, Li & Hedge 1994), all native to Eurasia. The taxonomy of Hyssopus is highly contested. Within Hyssopus officinalis several subspecies have been described (Sell & Murrell 2009) and some of these are sometimes given specific rank. Hyssopus officinalis is widely cultivated as a medicinal plant, for its oil or as an ornamental.
According to recent molecular data Hyssopus is embedded in Dracocephalum (Drew & Sytsma 2012).
Literature:
Borisova A.G. (1977) Hyssopus. In: Shishkin B.K. (ed.), Flora of the U.S.S.R., vol. XXI. Academy of Sciences of the USSR: 320-329.
DeFilipps R.A. (1972) Hyssopus. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 3. Cambridge University Press, Cambridge: 170-171.
Drew B.T. & Sytsma K.J. (2012) Phylogenetics, biogeography, and staminal evolution in the tribe Mentheae (Lamiaceae). Am. J. Bot. 99(5): 933-953. [available online at: http://www.amjbot.org/content/99/5/933.long?cited-by=yes&legid=amjbot;99/5/933&related-urls=yes&legid=amjbot;99/5/933]
Li H.-W. & Hedge I.C. (1994) Hyssopus. In: Wu Z.-Y. & Raven P.H. (eds.), Flora of China, vol. 17. Bejing, Science Press: 232. [available online at: http://flora.huh.harvard.edu/china/PDF/PDF17/hyssopus.pdf]
Mabberley D.J. (2008) Mabberley’s plant-book (3th ed.). Cambridge University Press, Cambridge: XVIII + 1021 p.
Sell P. & Murrell G. (2009) Flora of Great Britain and Ireland. Vol. 3 Mimosaceae – Lentibulariaceae. Cambridge University Press, Cambridge: XXVIII + 595 p.