Since the late 1700s, when Anquetil-Duperron and others made portions of the Avesta available to western scholarship, several scholars have sought a representative botanical equivalent of the haoma as described in the texts and as used in living Zoroastrian practice. Most of the proposals concentrated on either linguistic evidence or comparative pharmacology or reflected ritual use. Rarely were all three considered together, which usually resulted in such proposals being quickly rejected.
In the late 19th century, the highly conservative Zoroastrians of Yazd province in Iran were found to use Ephedra (genus Ephedra), which was locally known as hum or homa and which they exported to the Indian Zoroastrians. (Aitchison, 1888) The plant, as Falk also established, requires a cool (but not cold) and dry climate, i.e. it does not grow in India (which is either too hot or too humid or both) but thrives in central Asia. Later, it was discovered that a number of Iranian languages and Persian dialects have hom or similar terms as the local name for some variant of Ephedra. Considered together, the linguistic and ritual evidence appeared to conclusively establish that haoma was some variant of Ephedra.
From the late 1960s onwards, several studies attempted to establish soma as a psychotropic substance. A number of proposals were made, included an important one in 1968 by Robert Gordon Wasson, an amateur mycologist, who (on Vedic evidence) asserted that soma was an inebriant, and suggested fly-agaric mushroom, Amanita muscaria, as the likely candidate. Wasson and his co-author, Wendy Doniger O'Flaherty, drew parallels between Vedic descriptions and reports of Siberian uses of the fly-agaric in shamanic ritual. (Wasson, Robert Gordon (1968). "Soma: Divine Mushroom of Immortality". Ethno-Mycological Studies 1 )
In 1971, John Brough rejected Wasson's theory and again drew attention to ephedrine (in particular to that extracted from Ephedra sinica), and noted that it "is a powerful stimulant, and would thus be a more plausible preparation for warriors about to go into battle than the fly-agaric, which is a depressant." (for use of parahaoma by soldiers, see reference to the Ab-Zohr in Denkard 8.25.24). (Brough, John (1971). "Soma and Amanita muscaria". Bulletin of the School of Oriental and African Studies (BSOAS) 34 )
This was in turn contradicted in 1974 by Iranologist Ilya Greshevitch, who determined that, in small doses, fly-agaric was indeed a stimulant. (Greshevitch, Ilya (1974). Mémorial Jean de Menasce. Louvain: )
In 1989, David Flattery, with linguistic support from Martin Schwarz, concentrated again on Iranian haoma. The two again paid particular attention to the hallucinogenic properties that may be interpreted from the texts, and discounted Ephedra because they could not observe Zoroastrian priests becoming intoxicated.
They concluded that it was "therefore neither likely that Ephedra was a substitute for *sauma nor that it was *sauma itself" and that the ephedrine and pseudoephedrine alkaloids extracted from Ephedra had to be mixed with the extract from some other plant to achieve the described effects. Flattery proposed the second plant was Peganum harmala (harmal, harmel, Syrian rue, see also harmaline), known in Iranian languages as esfand, sepand or other similar terms related to Avestan word spenta ('sacred', 'holy'). Flattery considered harmel to be the real haoma, with ephedra only being the secondary ingredient in the parahaoma mixture. (Flattery, David Stophlet and Schwarz, Martin (1989). Haoma and Harmaline. Berkeley: )
This latter supposition was strongly objected to, primarily because harmel grows in India and there was therefore no obvious reason why the Vedic or Zoroastrian priests might abandon it in favour of a surrogate.
The most likely candidate of the non-hallucinogenic, stimulant hypothesis is a species of the genus Ephedra. Ephedrine, the agent substance in this plant, has a chemical structure similar to amphetamines, and it results in high blood-pressure, and according to anecdotal reports, it has a stimulating effect more potent than that of caffeine.
Ephedra plants are shrubs, measuring between 0.2 and 4 meters, with numerous green or yellowish stems. There are about 30 species, mainly Eurasian. The species growing in mountainous regions have the highest ephedrine content (up to 3% in the case of Ephedra equisetina). The marrow in the stems is brown-coloured in some species, reminiscent of Sanskrit babhru ("greyish-brown"), used exclusively in the Vedas to describe the extract.
The different species of Ephedra are not well known, and their taxonomy is in a state of confusion. Assuming a Pontic-Caspian home of Indo-Iranian religions (see Kurgan), the only likely candidate is Ephedra distachya, still used in Iranian folk medicine.
In 1989, in a highly influential text, Harry Falk pointed out that both the Flattery and Wasson arguments assumed that haoma was hallucinogenic, although the effect desired by Zoroastrian and Vedic ritual use was not. Falk noted that, in the texts, both haoma and soma were said to enhance alertness and awareness, did not coincide with the consciousness altering effects of an entheogen, and that "there is nothing shamanistic or visionary either in early Vedic or in Old Iranian texts," (Falk, 1989) nor could the small doses administered in living Zoroastrian custom justify its consideration as an inebriant. Living custom also does not give the extract enough time to ferment.
Falk established that the effect of the alkaloid ephedrine was, in many respects, similar to adrenaline, but "its actions are less intense but more prolonged than those of adrenaline, and, most important, it prevents sleeping." Chemically, ephedrine is similar to amphetamine. Falk also asserted that the three varieties of ephedra that yield ephedrine (geradiana, major procera and intermedia) also have the properties attributed to haoma by the texts of the Avesta. (Falk, 1989)
In 1994, Viktor I. Sarianidi claimed that ancient ritual objects found at BMAC archeological sites in Central Asia bore traces of Ephedra stalks and Papaver (poppy) seeds. In 1995, Harri Nyberg investigated the specimens provided by Sarianidi but could not confirm the claim (cited in Houben, 2003). Another site provided material which Sarianidi had declared contained traces of Ephedra, Papaver and Hemp (Cannabis) in 1998–1999]. It was analysed in 2002–2003 by three independent teams, but they found no traces of the claimed contents. (Bakels, 2003)
Nonetheless, in the conclusion of his observations on the 1999 Haoma-Soma workshop in Leiden, Jan E. M. Houben writes: "despite strong attempts to do away with Ephedra by those who are eager to see *sauma as a hallucinogen, its status as a serious candidate for the Rigvedic Soma and Avestan Haoma still stands" (Houben, 2003). This supports Falk, who in his summary noted that "there is no need to look for a plant other than Ephedra, the one plant used to this day by the Parsis." (Falk, 1989)
The mushroom theory is supported by later Tibetan Buddhist legends connected with urine-drinking, and it is indeed possible that in Tibet, the shamanistic practice of eating psychedelic mushrooms, and subsequently drinking the urine of the one who has taken the mushroom, still containing much of the agent substance, has been connected with Vedic terminology surrounding Soma, but this would of course not imply that the plants used in Tibet were identical to the original Indo-Iranian plant.
Terence McKenna in his book "The Food Of Gods" takes issue with the Amanita muscaria theory and suggests the psilocybin-containing Psilocybe cubensis mushroom as a *sauma candidate. McKenna argues that effects of the Amanita muscaria mushrooms contradict the description of the properties described in the Rigveda. Amanita muscaria mushrooms have properties that are arguably more deliriant than hallucinogenic. Psilocybin, the active psychoactive component in Psilocybe cubensis, on the other hand, has a strong hallucinogenic nature.
Regardless, Swami Rama admits to being ignorant of whether or not Bhairavdutt's soma is the same plant described in Vedic scripture. Bhairavdutt convinces the swami to join him in partaking the soma, which Bhairavdutt brews by mixing the soma-rasa (soma juice) with ashtha varga (a mixture of eight herbs). The taste, says Swami Rama, is "a little bit bitter and sour." Soon after drinking the concoction, Bhairavdutt becomes inebriated, strips himself naked, and dances wildly, claiming he is Shiva. His behavior becomes so unsettling that several students who had come to visit the swami earlier that morning attempt to restrain the apparently slightly-built Bhairavdutt, but are unable to do so as he becomes "so strong that five people [cannot] hold him down." Meanwhile, Swami Rama develops a crippling headache in reaction to the soma, and collapses in a corner clenching his head. The whole incident proves so disturbing to the swami that he concludes that the benefits one gains from using psychedelics are significantly outweighed by the damage it causes.
From the description, Ephedra sp. is the only proposed candidate that fits reasonably well with Swami Rama's description. While not a succulent plant, it is nonetheless adapted to drought conditions. Though the term "succulent" is a fairly flexible description, it is not very probable that it would be used to describe Ephedra, though by no means impossible. On the other hand, it can arguably be described as a "creeper" (it is a low-lying, ragged shrub with scale-like leaves), unlike Pegalum harmala which is a fairly conventional erect "weed", and the habitat strongly suggests that the plant was neither lotus, nor the (well-known) hemp. The taste of the mixture as described is interesting; while the effect of the added herbs cannot be determined, Ephedra does have a slightly bitter taste, and for the ephedrine to be effectively extracted, the plant needs to be cooked in acidic (sour) liquid. The effects displayed by the scholar - euphoria and increased stamina - also indicate a primarily stimulant effect of the concoction. The causes for Swami Rama's adverse reaction are indeterminable, the symptoms being vague and unknown as to their exact cause. Still, as they are compatible with the effects of an ephedrine overdose and moreover, no hallucinogenic effects are described by Swami Rama, they do not indicate against the active ingredient being chiefly ephedrine.