Elder is sometimes called THE herbal remedy… all of its parts can be used for a huge variety of ailments, from cold and flu to provoking the flow of urine (and lady fluids), good with inflamed skin, soothes eyes, purgeth the tunicles of the brain, and even cures mad dog bites.
Culpeper had the following to say about Elder…
The elder-tree groweth in hedges, being planted there to strengthen the fences and partitions of ground, and to hold the banks by ditches and water-courses.
Government and virtues.
Both the elder and dwarf tree are under the dominion of Venus. The first shoots of the common elder boiled like asparagus, and the young leaves and stalks boiled in fat broth, doth mightily carry forth phlegm and choler.
The middle or inward bark boiled in water, and given in drink, worketh much more violently; and the berries, either green or dry expel the same humour, and are often given with good success to help the dropsy; the bark of the root boiled in wine, or the juice thereof drank, worketh the same effects, but more powerfully than either the leaves or fruit.
The juice of the root taken, doth mightily procure vomitings, and purgeth the watery humours of the dropsy. The decoction of the root taken, cureth the biting of an adder, and biting of mad dogs.
It mollifieth the hardness of the mother, if women sit thereon, and openeth their veins, and bringeth down their courses: The berries boiled in wine performeth the same effect; and the hair of the head washed therewith is made black.
The juice of the green leaves applied to the hot inflammations of the eyes assuageth them; the juice of the leaves snuffed up into the nostrils, purgeth the tunicles of the brain; the juice of the berries boiled with honey, and dropped into the ears, helpeth the pains of them; the decoction of the berries in wine being drank provoketh urine: the distilled water, of the flowers is of much use to clean the skin from sun-burning, freckles, morphew, or the like; and taketh away the head-ach, coming of a cold cause, the head being bathed therewith.
The leaves or flowers distilled in the month of May, and the legs often washed with the said distilled water, it taketh away the ulcers and sores of them. The eyes washed therewith, it taketh away the redness and bloodshot; and the hands washed morning and evening therewith, helpeth the palsy, and shaking of them.
A good list of Elder references from other herbals here : https://www.rjwhelan.co.nz/herbs%20A-Z/elder.html