Herb
Bitter grace — beautiful, blue-green, and not to be handled lightly.
These are associations the community holds, not settled fact — the more a reading is shared, the bolder it sits.
Rue is the herb of regret in name only; the English pun is a coincidence, and the plant is named from the Greek. It was, for centuries, the great counter-poison and counter-magic of Mediterranean Europe. Brushes of rue sprinkled holy water in churches, which is why it acquired the name herb of grace. In Italy the cimaruta, a silver charm in the shape of a rue sprig, was worn against the evil eye, and in parts of southern Europe still is.
Craft keeps rue for protection, for breaking hexes, for scrubbing a place clean of something unwelcome. It is one of the few herbs whose reputation is entirely about defence — nobody uses rue to attract anything.
It is also the entry in this list that most needs reading carefully. Rue is a bitter, powerful plant with a genuine history of use as an abortifacient, and its sap causes serious blistering burns in sunlight. It is beautiful, blue-grey and easy to grow, which is exactly the problem: it looks harmless in a border, and it is not.
Readings practitioners have offered, ordered by how many recognise them. Take what serves, leave the rest.
Carried forward
Nicholas Culpeper, The Complete Herbal (1653)
Culpeper: "It is an herb of the Sun, and under Leo." He recommends it against poisons and the bites of venomous creatures with total confidence, and — like almost every writer before the twentieth century — says nothing whatever about the burns.
Carried forward
Southern Italian folk practice
The cimaruta, a silver charm cast in the shape of a rue sprig and hung with moons, keys and other emblems, was worn against the evil eye, often pinned to an infant. Examples survive in quantity in museum collections.
Credit what you carry. Much of this comes from living traditions, and some of it from traditions that are closed — held by particular peoples and not offered for general use. Where you know whose practice a reading came from, name them; where you don't, say that too.