Hawthorn

Hawthorn, Crataegus monogyna and its relatives, is the May of English usage, the tree so identified with the month that it took its name, and the blossom of the Beltane and May Day festivities.

There is a chronological complication that is usually skated over. Britain moved from the Julian to the Gregorian calendar in 1752, losing eleven days. Hawthorn flowers when it flowers, and in much of England that is now toward the end of May rather than at the beginning; before the change, May Day fell nearer the natural flowering. Old May Day, 12 May, is still observed in a few places and is closer to the blossom. Anyone reconstructing a seasonal festival from the plant needs to know which calendar the tradition was formed in.

The taboo on bringing hawthorn indoors is well attested across England and Ireland: the blossom outside is auspicious, the same blossom on the table is unlucky and in some tellings brings death to the household. A physical explanation is available and is at least suggestive. Hawthorn flowers contain trimethylamine, which is among the first compounds produced by decaying animal tissue. The scent that is pleasant enough in the open air is, in a closed room, recognisably the smell of death. In a period when the dead were laid out at home, the association would have been immediate.

The fairy thorn, a lone hawthorn standing in a field, not to be cut, is a strong and comparatively recent-documented Irish tradition, and it has genuinely diverted road schemes.

Culpeper places hawthorn under Mars, and the ground is the thorns. This is the doctrine of signatures at its most literal: an armed plant belongs to the planet of weapons and wounds. It is the same reasoning that puts nettle under Mars for its sting, and it has the same weakness, it reads a defensive structure as a statement of pharmacological character, and the two have no relation.

The folk associations run somewhere else entirely. The fairy tree, the May blossom, the guardian of the boundary hedge: none of this is martial in any sense Culpeper's scheme would recognise, and it constitutes a body of tradition that simply does not intersect with the planetary one. They coexist without engaging.

The modern use is different again and is the most substantial of the three. Hawthorn leaf, flower and fruit extracts are among the better-investigated herbal preparations for cardiac indications, particularly chronic heart failure, and are a licensed phytomedicine in Germany. The constituents of interest are oligomeric procyanidins and flavonoids, and the proposed mechanisms include mild positive inotropy and vasodilation. The trial evidence includes some reasonable-quality work with modest positive findings on symptom measures, and a large mortality trial that did not show benefit on its primary endpoint. This is described here as the state of a research literature, not as a recommendation, and hawthorn interacts with cardiac medication.

That a plant assigned to Mars for its thorns turns out to act on the heart is a coincidence, and it is worth resisting the temptation to make it more than one.