Soapwort can grow to around five feet tall and has a spread of about a foot, with pinky-white flowers which bloom from July to September. These look a little like the garden flowers Sweet William which is why it is sometimes called wild Sweet William. It is a member of the Carnation family of plants; Caryophyllaceae, so is related to cloves. Like the soapnut (reetha), it produces a lather; or rather the leaves, stem and root do, when they are swished around in water. This gives rise to another name for the plant, latherwort. It is also sometimes called Fuller’s herb, and this is because it was used in the process of fulling textiles. The plant used to be used in woollen mills to gently wash newly made cloth to make it thicker, this was the fulling process. It can still be seen in Europe growing around sites of old woollen mills. It has also been used in the past to wash sheep’s wool before shearing.
Other names for the plant include Bouncing Bet which is a curious name with dubious origins. It has been suggested that country bar-maids in Britain were often called Bet or Betsy and they used the leaves and stems of soapwort plants to scour tankards and beer bottles to get them clean and this is how the plant got its name.
As far back as the 8th century BC the Assyrians were using this plant or a similar one to wash clothes and cloth, just as the ancient people of the Indian subcontinent used the soapnut.
Soapwort is native to Europe , including the British Isles , Scandinavia and temperate North Africa . It is sometimes known as Lychnis saponana. The word ‘sapo’ comes from the Latin meaning soap and this plant contains saponins which are toxic, so it is better not to use it to make shampoo with as it irritates the eyes. You can leach the saponins from the plant by soaking it in water but this is a time-consuming process. To make soap for washing clothes you can simply boil the whole chopped plant (especially the root) to make a gentle, effective cleaner which will not harm antique fabrics or delicate ones. If you use it for delicate laundry you can add a few drops of essential oil such as lavender or rose oil to improve the smell of the clothes as soapwort is virtually odourless.
The plant has been used in traditional medicine for a number of ailments, including for T.B., jaundice and other liver problems, as well as for syphilis. As regards the latter disease, Culpeper the 17th century herbalist states that soapwort is especially effective when mercury treatment fails.( It was customary to use mercury to cure syphilis.) However it is unwise to take any infusion or decoction of this plant internally as it irritates the digestive system. It can also destroy red blood cells and paralyze the part of the central nervous system that controls the dilation of blood vessels. It is however useful for skin problems and itching. The juice from the leaves and/or the root can be applied to the skin for acne, eczema and any other skin problem. It is said that a decoction of the root can take away discoloration from a black eye, but you have to be careful not to get any juice in your eye. It’s better to use mallow!
In clinical trials both in vitro and in animals it has been found that saporin –S6 extracted from the seeds has had some anti-cancer properties, but more research is needed.(June 2011 L Polito).