What the hell is that stuff they put in a variety of drinks made from? It tastes like shit straight, but it makes a hell of an Old Fashioned. Whats in it? Is ther a bitter plant? Is it a combo of a bunch of nasty bitter foods. Come to think of it, what exactly is a bitter flavor? Sweet is a variety of sugars, salty is salt, sour is acid, but what are bitters?

The facts expressed here belong to everybody, the opinions to me. The distinction is
yours to draw…

Omniscient; BAG

My dad always insisted bitters contained owl shit, but dad was not a great source for facts.

Encyclopaedia Brittanica sez:

Bitters: any of numerous aromatized and often alcoholic liquids containing
bitter substances (chiefly alkaloids, glycosides, or complexes), used
as tonics, liqueurs, appetizers, digestives, flavourings, and
ingredients to add tang or smoothness to alcoholic drinks. Bitters
are prepared according to secret recipes by several manufacturers
using bitter herbs, leaves, fruits, seeds, or roots and sometimes
alcohol or sugar. The taste is imparted by substances such as orange
peel, gentian root, rhubarb root, hop flowers, quassia-wood chips,
cascarilla, cinchona bark, and quinine. Aroma is provided by
juniper, cinnamon, caraway, anise, nutmeg, camomile, cloves, and
other flavouring agents. Bitters are usually named according to the
ingredient giving the predominant flavour, such as orange bitters
and peach bitters. The alcoholic strength varies but is generally
about 40 percent by volume.

Medicinal bitters, few in number and of minor therapeutic value,
include compound tinctures of absinthe and of aloes. Early Hebrew
history records the addition of sweet-scented or bitter herbs to
wine in order to improve and give variety to the flavour. The
preparation of aromatic liqueurs originated in France around 1533,
and their use spread quickly over the world.

Hey, just read the label. Remember, it is not made from the Angostura root.

Try Peychaud’s bitters, from N’Awlins, for a change from Angostura. Makes a nice drink.

Especially since owl shit, proper, does not exist. Anything solid an owl did not digest gets hacked up in the form of pellets, available from any good scientific catalog for the purpose of dissection.

“If A=B, B=C, and C=D, do not get a job proofreading” --Quid’s Theorem

To answer one of the original questions:
bitter = alkaline = ability to taste alkaloid poisons.