Dye Plant--Sawwort, Serratula tinctoria, Obscure Historic Yellow Dye

Persian knapweed Centaurea dealabata

Note added August 24, 2015: I had the identification of the plant wrong. Yet most of the post is correct because I talk about my experience with the plant separately from my research on dye history. I will make changes below in this font so it is clear. I have changed all the plant identications. I won't change the post title.

I like rescuing plants. You know, taking a sickly little plant, giving it good light and regular water and watching it recover. My relationship with sawwort--Persian knapweed really-- began that way. 

I was new to Colorado in fall of 2006 and finding plants for the yard of my new house. So I was looking on the end-of-the-season garden racks for promising marked-down perennials at McGuckin's Hardware Store in Boulder ("Colorado's Favorite Store"!). I chose a pot or two and got chatting with the clerk. She pointed me to the edge of the garden shop where a couple of run-down, sad-looking plants slumped over the edge of their pots and said I could have them, no charge. How could I resist?!



I took them home--three pots if I remember right--and stuck them in the ground in the garden.

Persian knapweed Centaurea dealbata

They lived and grew. I liked the flowers--the internet describes the flowers as "thistle-like." I am more reminded of bachelor buttons (Centaurea cyanus, called cornflower in Europe), particularly the perennial one, Centaurea montana, which I grew for a while. (Link) 

bachelor buttons, Centaurea cyanus

Whether it reminds you of bachelor buttons or thistles, all of them are members of the huge sunflower (or thistle or daisy) plant family, Asteraceae.

I saw sawwort in a picture in Cardon's book on dye plants and wondered if it was the same. I checked the plant I had against a couple European plant books and the web but never thought to compare it to Centaurea dealbata. The similarity of the two species is strong, but sawwort is more slender. See Centaurea dealbata   See Serratula tinctoria  Both have serrate leaves at the base and "thistle-like" pink-purple flower heads.

This is all true and accurate about sawwort: 
My sawwort is Serratula tinctoria and native to Europe. North America has a few native plants called sawworts, also in the sunflower family and probably related to Serratula tinctoria, but there are no serratulas native to North America.

Serratula tinctoria is found from southern Scandinavia across all of Europe except Portugal and Spain. 

The scientific name Serratula and the English common name sawwort refer to the "saw-like" leaves. ("wort" is an old word for "plant").

The word tinctoria in sawwort's name refers to its history as a dye plant.

Persian knapweed Centaurea dealbata, leaf

And therein lies the neat part of my story:

I have been growing sawwort  Persian knapweed since 2006 but paying it almost no attention. It is pretty in the spring when it leaps out of the ground and comes into bloom. But by late summer the stalks flop over, falling onto the plants around them and looking distinctly sloppy.

Persian knapweed, sprawling

Persian knapweed Centaurea dealbata

I was starting to think that maybe I didn't want these plants in that flower bed when I leafed through Dominque Cardon's book  Natural Dyes and found sawwort listed in the historic yellow dyes. "Since the Middle Ages, sawwort has been used in several European textile centers...In Tuscany in the 14th and 15th centuries it was as highly valued as weld as a dye for dyeing woollen cloth yellow and green." (p. 178)

Bad identification! My Persian knapweed looks a lot like sawwort, but its different. This is a recurrent problem: it is a big world with a lot of plants and no resource that include all the possibilities. None of the European or American flower books I own include Persian knapweed (Centaurea dealbata) though they have numerous other knapweeds. When you don't know there are other possibilities, it is easy to get plant identifications wrong. I'm pleased to have caught this error, but unhappy that I made it. 

Master dyer Sheron Buchele Rowland--who, like me, had never dyed with sawwort--and I naturally had to try it.  We got a very nice yellow and olive. These were done with Persian knapweed: it is clearly a good dye plant.

dyed with Persian knapweedt: yellow has alum mordant;
olive has iron mordant; yarns are wool, scarves are silk

Sheron then pressed individual leaves against mordanted silk and got the effect below:

Sheron Buchele Rowland applying Persian knapweed
 leaves to silk

Persian knapweed leaf patterns dyed on a white scarf

Sawwort is the commercial dye, not Persian knapweed. These next two paragraphs are correct for sawwort:

There are lots of plants that make yellow dyes but only a few have been used commercially  (see earlier post LINK). I always wonder why one would choose one yellow dye over another. There may be differences in the shades of yellow produced but that is rarely if ever mentioned. 

One reason professional dyers chose particular plants for yellows or olives was color fastness. Sawwort, weld (Reseda luteola) and dyer's mulberry (Maclura tinctoria, LINK to my blog about it) produce colors that do not fade noticeably in sun or with washing. Given color-fastness, professional dyers, from the Middle Ages up through the late 1800s when aniline dyes replaced plants for commercial dyeing, seem mainly to have wanted whatever yellow dye they could get cheaply in large quantities.  

In my yard, sawwort is an easier plant to live with than weld. Since I don't have sawwort I can't compare. What I say about weld is true. Weld is a biennial that is seeding into everything. In three years I have gone from a tidy bed of weld rosettes in the dye garden to 100s of seedlings all around the dye garden and down the path. Sawwort is dioecious (has "male" and "female" plants). I seem to have both because I have small plants as well as the ones I started with. In 8 years I have probably 10 small sawwort plants. Compared to weld, it hardly reproduces at all. A farmer raising dyes to sell to dyers might like the rapid reproduction. On the other hand, weld doesn't live very long (about 2 years) while sawwort is perennial (at least the 6 years I've had them). Weld seeds have to be planted (or managed) every year or two while each year sawwort could be cut from established plants. Cardon says sawwort was harvested from wild populations, so perhaps it was used commercially where it was easily harvested and not elsewhere.

weld plants in flower

And sawwort Persian knapweed has the nifty leaves for making patterns on the cloth. Weld's leaves are narrow and only rarely more than 3" long. The dye from dyer's mulberry comes from the wood not the leaves. Neat leaves that transfer color is of course a modern benefit but it is an argument for growing sawwort.Persian knapweed.

I took home unwanted plants and they turned out to be lovely traditional European dye plants. It was very much a plant rescue success for someone who likes dyes, plants and history!!!

AND -- it lets me ask: what plant of unexpected qualities is growing near you?!
This is even truer than I thought when I wrote it, for I have seen nothing about knapweeds as dyeplants. Persian knapweed is widely sold as a garden plant in the U.S. and I recommend it as a dye plant.

I made a mess of the post with my corrections but it seems better to correct the information than to take it down without explanation. I apologise for a year of misinformation.

Comments and corrections welcome.


References

Cardon, Dominique. Natural Dyes. Sources, traditions, technology and science. Archetype Publications, London. 2007.

Kathy Keeler

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