AKA: Old man, lad’s love, appleringie, garderobe, Our Lord’s wood, maid’s ruin, garden sagebrush, European sage, witherwood, lemon plant
Historically Used to Treat: Gas, cramps fever, eye problems, acne and blemishes, worms and childhood parasites, splinters and thorns, dry ulcers/old wounds, venereal disease, baldness, hysteria, pain, swelling, gangrene, urinary tract infections, jaundice
Other Uses: Aromatic bitter (similar to related wormwood), and/moth/snake repellant, nasal spray for allergies, odor neutralizer, yellow dye, sometimes used in absinthe instead of wormwood, said the help a beard to grow.
“It is a gallant….plant, worthy of more esteem than it hath.” - Nicholas Culpeper, 1653
CAUTION: Contains thujone, may be toxic in large quantities
Culpeper's The Complete Herbal (1653) - On Southernwood
A Brotanum, mas, fœmina.
Southernwood, male and female. It is hot and dry in the third degree, resists poison, kills worms; outwardly in plaisters, it dissolves cold swellings, and helps the bitings of venomous beasts, makes hair grow: take not above half a dram at a time in powder. 
Culpeper also lists Southernwood as an herb that cleanses, ‘provokes the terms’ (causes menstruation) in women, and resists poisons .