"When the Broom's in season so is kissing"

With current knowledge, it would be a little reckless to ingest this plant except in forms where the active ingredients had been extracted and measured in a laboratory and were being prescribed by a qualified practitioner. In the past however it was a heavy hitter in the armoury of witch and warlock, spaewife and canny man. In the far past the poor had to find their powerful drugs within walking distance whatever it was they wanted them for: to cure, kill, abort, de-louse, get rid of worms or to get stoned out of their mind. Nobody was going to import them for them from the other side of the globe. Broom was once much used in both folk and orthodox medicine.

Its coming into flower at Beltane marked the time to leave the oppressive confinement of winter quarters both for seasonal itinerants and for those who practised the transhumance grazing, that was for so long a part of Highland life, travelling twice yearly between low-ground village and higher altitude summer shieling. Nowadays it is still one of life's cheaper treats in summer, to lie like a cat in the sun under broom losing quotidian thought in the sky's infinite blueness getting just a little tipsy on the scent of its blossom and listening to its ripe seed pods exploding with a sound like distant gunfire.

Non-medical uses of broom
A fibre is obtained from the bark, it is used in the manufacture of paper, cloth and nets. It is not as strong as the fibre from the Spanish broom (Spartium junceum). The fibre is also obtained from the root. The bark fibre is used to make paper, it is 2 - 9mm long. The branches are harvested in late summer or autumn, the leaves removed and the stems steamed until the fibres can be stripped. The fibres are cooked for 3 hours in lye then put in a ball mill for 3 hours. The paper is pale tan in colour. The bark is a good source of tannin. Modern dyers report that the flowering tops of broom produce various shades of yellow, according to the mordants used; [Alum & Cream of Tartar = 'butter yellow']; [Tin = 'yellow']; [Chrome = 'golden']. A yellow and a brown dye are obtained from the bark. A yellow dye is obtained from the flowering stem. A green dye is obtained from the leaves and young tops. The branches are used to make baskets, brushes, brooms and besoms. They are also sometimes used for thatching roofs and as substitutes for reeds in making fences or screens. An essential oil from the flowers is used in perfumery. Growing well on dry banks and on steep slopes, it is an effective sand binder and soil stabiliser. Broom is one of the first plants to colonize coastal sand dunes. Like other leguminous plants it is a fixer of nitrogen. The plant attracts insects away from nearby plants. The wood is very hard, and beautifully veined. The plant seldom reaches sufficient size for its wood to be of much value, but larger specimens are valued by cabinet makers and for veneer.

Edible uses of broom
Now considered too toxic to use, contains toxic alkaloids that can depress the hearing and nervous systems and affect the function of the heart. The below is included for historical interest only.
The flower buds are pickled and used as a substitute for capers. They can also be added to salads. Some caution is advised, although probably the safest part of the plant, see the note on toxicity. The tender green tops of the plant have been used like hops to give a bitter flavour to beer and to render it more intoxicating. The roasted seed has been used as a coffee substitute.
Broom wine and beer, from the tips, seem to have once had a reputation as a serious mind altering substance. As noted in Allan Ramsay's (Oct 15, 1686 – Jan 7, 1758, his eldest child was Allan Ramsay the painter 1713-84) ELEGY ON MAGGY JOHNSTON , who died Anno 1711.
[Note: Maggy Johnston liv'd about a Mile Southward of Edinburgh, kept a little Farm, and had a particular Art of brewing a small Sort of Ale agreeable to the Taste, very white, clear and intoxicating, which made People who lov'd to have a good Pennyworth for their Money be her frequent Customers. And many others of every Station, sometimes for Diversion, thought it no Affront to be seen in her Barn or Yard.]:

"Some said it was the pith of Broom,
That she stow'd in her masking- loom,
Which in our heads rais'd sic a foom;
Or some wild seed,
Which aft the chaping stoup did toom,
But fill'd our head."

Wine made from the flowers also has a reputation for a producing a more than alcoholic intoxication.

Medicinal uses of broom
Now considered too toxic by many authorities; expert use only, for most of its uses there are safer substitutes.
Cardiotonic, Cathartic, Diuretic, Emetic, Insecticide, Vasoconstrictor, Vermifuge.
Definitons of medical actions

Broom is a bitter narcotic herb that depresses the respiration and regulates heart action. It acts upon the electrical conductivity of the heart, slowing and regulating the transmission of the impulses. The young herbaceous tips of flowering shoots are cardiotonic, cathartic, diuretic, emetic and vasoconstrictor. The seeds can also be used. The plant is used internally in the treatment of heart complaints, and is especially used in conjunction with Convallaria majalis (Lily of the Valley). The plant is also strongly diuretic, stimulating urine production and thus countering fluid retention. Since broom causes the muscles of the uterus to contract, it has been used to prevent blood loss after childbirth. Use this herb with caution since large doses are likely to upset the stomach. The composition of active ingredients in the plant is very changeable, this makes it rather unreliable medicinally and it is therefore rarely used. This herb should not be prescribed to pregnant women or patients with high blood pressure. Any treatment with this plant should only be carried out under expert supervision. The young herbaceous tips of flowering shoots are harvested in spring, generally in May. They can be used fresh or dried. They should not be stored for more than 12 months since the medicinally active ingredients break down.

Historic: The most common traditional usages of this plant seem to have been as a vermifuge for both humans and horses, using the fresh green tips and as an insecticide for head lice, a strong brew of twigs used as a scalp rub. The plant also had a reputation for treating dropsy, jaundice and expelling poisons from bites by venomous insects. In Fife, the miners used broom tops and nettles, infused in water as a treatment for dropsy. In Russia it had an optimistic reputation as a treatment for Rabies. These uses are not given in more recent works, there is now more concern about the toxicity and unpredictable level of active ingredients of the herb than there used to be.

Sources:
Plants For A Future, www.pfaf.org/index.html,
Flora Celtica, www.floraceltica.com/, Flora Celtica is an international project based at the Royal Botanic Garden Edinburgh,
ELEGY ON MAGGY JOHNSTON , Allan Ramsay collected poems 1721 edition. Ramsay: The Works: a machine-readable transcript is at http://quartet.cs.unb.ca