Infused Oils: St John's Wort

St John's Wort (Hypericum perforatum) is a herb rarely out of the papers due to its use in cases of mild to moderate depression. However that is just one of the many applications of this intriguing herb.

St John's Wort in Bloom!

From midsummer onwards St. John's Wort produces a profusion of bright yellow flowers and these, along with the upper aerial parts, can be steeped in oil to make a deep red coloured infusion which is very useful to have around the house as an external remedy for healing wounds, muscular aches, pains, spasms and local nerve irritation.

Of course correct identification is essential. There are a number of species in the Hypericum genus but only Hypericum perforatum is traditionally used in Irish herbal medicine. If you hold the underside of the leaf up to the light you will lots of tiny little perforations (hence the Latin name perforatum). Other species of St John's Wort don't have these identifying marks, which incidentally are not actually perforations but layers of colourless resins and oils considered the most active parts by some herbalists.

Hypericum androsaemum L.

Hypericum androsaemum, also known as Tutsan, is mentioned in Culpeper to 'purgeth the choleric humours' however in Australia and New Zealand it is considered an invasive weed, while the red and black berries it produces are toxic. This is why correct identification of herbs is so important. Meanwhile Hypericum patulum is a more ornamental garden variety forming a dense shrub with large yellow flowers as shown in the picture below. Another species used in herbal medicine is the Rose of Sharon, Hypericum calycinum, a noted antibacterial and Mediterranean native.

Hypericum patulum 'Hidcote'

The St John's Wort I use is the native upright perennial, growing up to 90 cm. It grows across Ireland, Europe, Asia and is cultivated elsewhere preferring open, sunny situations and dry calcareous soils. The smooth stem branches in its upper part, bearing opposite, sessile, oblong leaves which exhibit numerous translucent oil glands (the perforations), as well as a few dark ones on the underside. The bright yellow five-petaled flowers, which are borne in a terminal corymb, have over fifty stamens, fused in the lower part into three bundles. The long lanceolate petals and shorter sepals are marked with dark dots. The fruit is a capsule which opens by three valves. RH Weiss has noted the raised lines appearing down the stem which is botanically unusual. Most stems are either round or square (as in the Lamiaceae for example). The lines on H.perforatum however make the stems appear to be flat so this feature, along with the 'perforations' are a good aid in correct identification. 

I harvest St John's Wort usually in late July and August (being northerly). This year due to the wet summer, the flowers are later than usual. I pick the flowers, seed pods and  upper aerial parts (top 15cm) on a dry sunny day after the dew has evaporated. I use well-maintained sharp secateurs so I can make clean cuts. Ragged cuts can be a point of entry for disease. It is important not to take too much so the plant can regenerate. I take approximately one third of the plant but I leave a good few flowers for bees and other insects. The next bit is very important - let the herb wilt a little in the sun for a few hours. This lessens the overall water content and can help to prevent mould later on (aromatic herbs are an exception to this general rule however).

It also allows any creatures living on the plant a chance to find pastures new! Once your herbs have wilted (leave them for at least a few hours), they are then ready for preparation. Take a good look and remove any damage, eaten or diseased parts. Quality control is good practise.

You will need your wilted herb, sufficient oil to cover the herb, a container in which the infusion will take place, and later a clean airtight container and the all-important label (although the deep red colour is always a bit of a giveaway).

I advise using a good organic oil such as sweet almond or olive oil (although passion flower is very good for this particular herb). I add a teaspoon of vitamin E liquid per 500ml to prevent rancidity and improve shelf-life though this is optional.

Because the plant material is rather fine I chop it a little with a pair of sharp kitchen scissors.

Place in a container and pour the oil so that all plant materials are covered. Use a wooden spoon and stir thoroughly to tease out any air bubbles. Sore in a jar with an airtight lid and label. Add more oil if necessary in the days ahead as the plant material will absorb the oil. Shake and stir from time time. All the herbal parts should be immersed in oil as any bits sticking out are liable to mould. You can leave the jar on a sunny window ledge or in a cool cupboard but I prefer to let the sun at this particular herb. Check regularly and your infused oil should be ready to filter in 6 weeks.

Filter the oil through muslin into a clean container, squeeze those last few drops (which are often the best of quality) and label. Include the date giving you a Best before date of approximately 12-18 months. The oil will keep longer especially if you add more Vitamin E regularly and refrigerate. For an even richer oil, and depending on the time of year, you may wish to repeat the process, continually strengthening the finished oil, however once is enough for a good quality oil.

You can use this oil EXTERNALLY for a number of conditions such as aches and pains or nerve irritation. Care should be taken on open cuts if any infection is present. The oil makes a good moisturiser and can of course be added to other preparations.

Traditional preparations and in particular the infused oil from SJW flowers remains one of the most popular and curative topical remedy against ulcerations and burns. The presence of the characteristic polyprenylated acylphloroglucinol derivatives, namely hyperforin and analogs are instead related to the oil's therapeutic activity. Indeed, it is well known that hyperforin has a potent antibacterial activity. (Isacchi et al, 2007).

The internal use of St John's Wort is another matter entirely and in Ireland it is restricted to practitioner use only unfortunately, largely because the regulators don't seem to understand herbal medicines and how they work but that's another story for another time. For an excellent clinical discussion on St John's Wort interactions in that regard by herbalist Jonathon Treasure see: http://www.herbological.com/images/downloads/SJW.pdf