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Night to the Soma-drinker come, for his enjoyment, these pure drops,
The Somas mingled with the curd.
Thou, grown at once to perfect strength, wast born to drink the Soma juice, Strong Indra, for preeminence.
O Indra, lover of the song, may these quick Somas enter thee:
May they bring bliss to thee the Sage.
— Rig Veda, HYMN V. to Indra
In Vedic times, Soma was a plant given as an offering to the gods. There was great mysticism and spiritual power surrounding the plant. So much so that it was considered a deity in its own right leading many to search for the true identity of this revered plant.
In the Rig Veda, Soma is mentioned as existing in all plants (RV X.97.7) and many different types of Soma are indicated. Water itself, particularly that of the Himalayan rivers, is a kind of Soma (RV VII.49.4). In Vedic thought, for every form of Agni or Fire, there is also a form of Soma. In this regard, there are Somas throughout the universe. Agni and Soma are the Vedic equivalents of yin and yang in Chinese thought.1
Many scholars believe the plant ephedra (Ma huang in Chinese herbalism) was the main Soma plant. Ephedra grows commonly in Afghanistan and Iran, and was the main Soma plant of the Persians. Ephedra is common in different places in India even today, and is sometimes called Somalata. While ephedra may have been commonly used, it was not the only plant, nor does it resemble the Soma plants described in the Rig Veda.
The Atharva Veda (AV XI.6.15) mentions five great plants of which Soma is the best, including marijuana, barley and darbha (kusha or durva), showing that many plants had Soma-like qualities. Here Soma is again connected with another type of reed (darbha, Saccharum cylindricum), which could have easily been pressed to get a juice, much like sugarcane. Soma is also connected with marijuana, suggesting that mind-altering plants were regarded as different types of Soma. In other places, Soma is connected with kushta (Saussurea lappa), a kind of spicy nervine, and with the Ashvattha fig tree and said to grow in the Himalayas in the Atharva Veda (AV XIX.39.5, 6).1
There where the broad-based stone raised on high to press the juices out, O Indra, drink with eager thirst the droppings which the mortar sheds. [01-028] HYMN XXVIII Indra.
In the Vedas, the juice of Soma was extracted by stone grinding or cooked with grains such as barley (yava), milk (go) or curds (dadhi). Soma was often used with ghee (ghrita) and honey (madhu) and soma was often called madhu (honey or mead). Special herbal honey preparations and herbal ghee preparations were additional types of Somas. Soma is also connected to lotuses and other flowering aquatic plants.1
The great Ayurvedic doctor, Sushrut, mentions 24 Soma plants, growing mainly on Himalayan lakes. He mentions 18 additional plants, which are mainly nervine herbs. Soma, therefore, was likely part of an entire science of sacred plant preparations and not just one plant in particular.1
In yogic and spiritual practices, Soma is a nectar secreted from the pineal gland during deep states of meditation. This amrita is thought to drip down and mingle with the heart chakra, aligning the heart and mind. Soma at a yogic level refers to the crown chakra, which is opened by Indra (yogic insight) and releases a flood of bliss throughout the body. This inner Soma is the main subject of the Vedic hymns, though outer Somas were also important.1
Soma was an important part of vedic rituals, spiritual practices and shamanic medicine. Given its transformative nature, it is no surprise that Soma took on many different forms. While we may never know which plants were actually used, we can be certain of the reverence that Soma merited in ancient times.