Willd. ex Schult.
Turnera microphylla Ham.
Turnera diffusa, known as damiana, is a shrub native to southwestern Texas in the United States, Central America, Mexico, South America, and the Caribbean. It belongs to the family Passifloraceae.
Damiana is a relatively small shrub that produces small, aromatic flowers. It blossoms in early to late summer and is followed by fruits that taste similar to figs. The shrub is said to have a strong spice-like odor somewhat like chamomile, due to the essential oils present in the plant. The leaves have traditionally been made into a tea and an incense which was used by native people of Central and South America for its relaxing effects. Spanish missionaries first recorded that the Mexican Indians drank Damiana tea mixed with sugar for use as an aphrodisiac.
Damiana has long been claimed to have a stimulating effect on libido, and its use as an aphrodisiac has continued into modern times. More recently, some corroborating scientific evidence in support of its long history of use has emerged. Several animal testing studies have shown evidence of increased sexual activity in rats of both sexes. Damiana has been shown to be particularly stimulating for sexually exhausted or impotent male rats as well as generally increased sexual activity in rats of both sexes. It has also been shown that damiana may function as an aromatase inhibitor, which has been suggested as a possible method of action for its reputed effects.
Damiana might be effective as an anxiolytic.
Damiana is an ingredient in a traditional Mexican liqueur, which is sometimes used in lieu of Triple Sec in margaritas. Mexican folklore claims that it was used in the "original" margarita. The damiana margarita is popular in the Los Cabos region of Mexico.
In the state of Louisiana, Damiana is considered a "prohibited plant" along with 39 other plants by Louisiana State Act 159, effective 8 August 2005. Any combination of any of the parts, leaves, stems, stalks, seeds, materials, compounds, salts, derivatives, mixtures, preparations, or any resin extracted from any part of the plant is illegal to possess or distribute for human consumption in the state of Louisiana. This was due in part to an increase in the number of synthetic cannabis overdoses from a variety of chemically-infused plant material formulations, most of which contained Damiana as a primary ingredient.
A product known as "Black Mamba", labelled as containing "100% Damiana", has been on sale in the UK; ill effects from its use have been reported. MP Graham Jones has called for the substance to be made illegal. "Black Mamba" is a combination of damiana and various synthetic cannabinoid receptor agonists, including JWH-018. Synthetic cannabis has caused negative side effects in a number of users. Damiana is considered safe when consumed in its natural form.
During Prime Minister's questions on Wednesday the 7th of March 2012 MP Nadhim Zahawi asked for action to be taken in relation to "Black Mamba", the Prime Minister responded:
- "We are determined to stamp out these so-called legal highs. The Home Office is aware of this particular drug. We now have the drugs early warning system which brings these things to our attention, but as he says, a decision needs swiftly to be made and I will make sure that happens." 
Black Mamba is now illegal in the UK.
- "Turnera diffusa". Integrated Taxonomic Information System. Retrieved 2011-01-29.
- "Taxon: Turnera diffusa Willd.". Germplasm Resources Information Network. United States Department of Agriculture. 2009-05-11. Retrieved 2012-01-03.
- Everitt, J. H.; Dale Lynn Drawe; Robert I. Lonard (2002). Trees, Shrubs, and Cacti of South Texas. Texas Tech University Press. p. 208. ISBN 978-0-89672-473-0.
- Gildemeister, Eduard; Friedrich Hoffmann (1922). The Volatile Oils. Volume 3 (2 ed.). Wiley. p. 183. Unknown parameter
- Arletti, R., Benelli, A., Cavazzuti, E., Scarpetta, G., & Bertolini, A. (September 1998), "Stimulating property of Turnera diffusa and Pfaffia paniculata extracts on the sexual behavior of male rats", Psychopharmacology 143: 15–19
- Estrada-Reyesb, K.R., Ortiz-Lópeza, P., Gutiérrez-Ortíza, J., & Martínez-Mota, L. (June 2009), "Turnera diffusa Wild (Turneraceae) recovers sexual behavior in sexually exhausted males", Journal of Ethnopharmacology 123: 423–429
- Kumar, S., Madaan, R., & Sharma, A. (2009), "Evaluation of Aphrodisiac Activity of Turnera aphrodisiaca", International Journal of Pharmacognosy and Phytochemical Research 1: 1–4
- Zhao, J., Dasmahapatra, A.K., Khan, S.I., & Khan, I.A. (December 2008), "Anti-aromatase activity of the constituents from damiana (Turnera diffusa)", Journal of Ethnopharmacology 120: 387–393, doi:10.1016/j.jep.2008.09.016, PMID 18948180
- Kumar, Suresh (February 9, 2005). "Anti-anxiety Activity Studies on Homoeopathic Formulations of Turnera aphrodisiaca Ward". Hindawi Publishing Corporation. doi:10.1093/ecam/neh069. Retrieved February 17, 2013.
- Damiana Liqueur at Damiana.net
- Perry, Charles (2007-06-20). "The unexpected thrill". Los Angeles Times.
- Pendergrast, Mark (2000). For God, Country, and Coca Cola: The Definitive History of the Great American Soft Drink and the Company That Makes It (2 ed.). Basic Books. pp. 24–30. ISBN 978-0-46505-468-8.
- Balch, Phyllis A. (2002). Prescription for Nutritional Healing: the A to Z Guide to Supplements (2 ed.). Penguin. p. 233. ISBN 978-1-58333-143-9.
- Legislature of Louisiana: Regular Session, 2010; Act No. 565; House Bill No. 173
- Richards, Brandon. "Fake pot now illegal in Louisiana." KPLCtv.com. (2010): n. page. Web. 3 Nov. 2011.
- "Damiana Legal Status." Erowid. N.p., 30 Oct 2011. Web. 3 Nov 2011.
- "Legal high fears as teens taken ill". The Sun. 2011-10-21.
- "Call for ban on ‘legal high’ Black Mamba backed by MP Graham Jones". The Lancashire Telegraph. 2011-12-08.
- Black Mamba Spice: A Cannabinoid Cocktail
- Fake Weed, Real Drug: K2 Causing Hallucinations in Teens | LiveScience
- DAMIANA: Uses, Side Effects, Interactions and Warnings - WebMD
- David Cameron MP, Prime Minister of the UK, House of Commons, 7th March 2012.
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