Nightshade

Nightshade (NS) is a variety of black-capped Britannian fungus which shares its name and several of its psychoactive and mythical properties with a family of noxious plants, noted on Earth for their use as poisons and witching herbs. Used as a reagent in Britannian and Serpent Islander magic, the nightshade fungus is often highly prized by magicians, as its harvest is a difficult undertaking.

Britannia
Growing only in the depths of Spiritwood and near the Shrine of Sacrifice, the Britannian nightshade mushroom could only be picked on the darkest of nights, when both moons were new. An extremely potent and toxic hallucinogen, mages made use of the sporing fruit of the nightshade cap by diluting it into a tea or crushing it into a meal, from which it would lend its energies to spells involving toxic or illusory properties. In the realm's later ages, the fungus was increasingly offered as a sale item by reagent vendors and herbalists, implying that it may have eventually been cultivated.

By the time of the late Age of Armageddon in Ultima IX, fungal nightshade appeared to have vanished from Britannia, possibly having faced extinction during the upheavals caused by the Great Cataclysm. Despite this dramatic shift, however, the mushroom seemed to have been readily replaced within magical practice by the still common leafy herbs of the nightshade family, which had long enjoyed use by Terran mystics for their similar psychoactive properties.

Earth
While Earth has no equivalent to the Britannian nightshade fungus (although similarly toxic fungal psychoactive such as the fly agaric are known to exist), various plants of the Terran solanaceae family, known as nightshades, have long been used in mystical practices.

Deadly nightshade (atropa belladonna), in addition to having both cosmetic and medicinal uses, has long been thought to have been an ingredient in the so-called "flying ointments," allegedly used by witches, and in creating the trance of  "twilight sleep," which early midwives were said to induce in their charges prior to childbirth. Members of the datura genus of nightshade have also enjoyed use as both entheogens and poisons in India and the Americas - and one variety, known as Jimson weed, has been used with some frequency as a recreational drug.



Trivia

 * While it seems likely that the herbaceous nightshade of Ultima IX is intended to be an analogue to the Terran solanaceae, its distinct five-leaf structure doesn't readily match any prominent members of the atropa or datura genera, which are the groups which would be most readily associated with magical uses of nightshade.