The lettuce that our Leech wants in her leech's bag is Lactuca virosa, the wild lettuce. Lactuca sativa has had most of the active principles bred out of it although Aelfrida would not have hesitated to use the sativa in a pinch, especially for lesser complaints.
It has been commonly used as a sedative and a sleep inducer. The plant gives off a milky sap when broken that is the source of “lactucarium” , a substance that has been used as a substitute and adulterant for opium.
The Leechbook of Bald calls lettuce “sleepwort” and recommends it steeped in wine and used as an “application of inner leechdoms” and as one of the ingredients in a salve for cancer.
Culpepper states in his Herball:
This Barley boiled in water cooleth unnatural and hot burning choler. In vehement fevers you may adde thereto the seeds of white Poppy and Lettuce,not onely to coole, but also to provoke sleepe.
He also states:
Lastly, it procures sleepe, assuages paine, moves the courses in women,and is drunke against the stingings of Scorpions,and bitings of spiders.
He informs us that:
Some (saith Dioscorides) mix the milkie juice hereof with Opium (for his Meconium is our opium)'
in the making thereof.
Mrs. M. Grieves gives an in depth accounting of the herb in her book, A Modern Herbal, from the early 1900's.
Today it's reportedly used as an anti-inflammatory, antioxidant and anti-microbial. It can help in lowering cholesterol. It's been employed to ease coughs and muscle spasms.
Research bears out the traditional sedative and sleep-inducing properties. Research also agrees with Bald that the lettuce is effective against at least certain types of cancer cells. I will state that I haven't been able to find any layman friendly research sites where I can corroborate any of these claims. You will want to do the search for yourself before proceeding with any uses other than a tasty salad.
Did I forget anything? Is there lettuce in your leechbag? Share how you prepare it in the comments below.
One other fairly universal use for lettuce was to control lust. Except in one country. Tomorrow I'll take a look at who says “for a good time eat lettuce!”