Friday, April 11, 2008

Retting

When I talked about xylem and phloem I mentioned that although phloem is largely parenchyma it contains some fibers. In some plants these fibers are an important part of the plant support and are tough, long and numerous. They are thus suitable for use in textiles. Linen, for example, is derived from the fibers of the flax plant. Fibers from hemp have been used for centuries to make a variety of products including clothing, paper and rope. Hemp is a term generally used to refer to Cannabis strains cultivated for industrial (non-drug) use.

Since the fibers are located in the phloem, they must be separated from the rest of the plant in a process called 'retting'. The traditional means of doing this was to soak the plant stems in water for several days. The only problem was that this would create foul stench. It is the stink produced that has given us valuable clues as to the abundance of hemp cultivation in medieval Europe because there are many written instances of towns banning the retting of hemp in particular locations. Here is some advice from 1580:

Now pluck up thy hemp, and go beat out the seed,
And afterward water it, as ye see need;
But not in the river, where cattle should drink,
For poisoning them, and the people with stink.

T. Tusser (1580) Five Hundred Points of Good Husbandry

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