Wednesday, August 7, 2013

Sisal here, sisal there, everywhere a sisal sisal...







Species name: Agave sisilana

Common name: agave, sisal

Location: teaching lab at Western

So once again we have a plant in a pot (the next few blogs will all be plants in pots) from my favourite course ever. This plant is from the same lab exercise as the previous one, flax (which you can read all about HERE). The point of this lab was to introduce students to five major fibres and where the come from, as well as providing them with visual representations of what the plants actually look like since most are pretty foreign concepts to the average undergrad student. The five plants we feature are hemp (not as a plant, but we have a huge display about hemp cultivation and harvesting, as well as products commonly made, and some uncommonly made, from hemp), flax/linen, banana/musa, sisal/agave, and cotton. We also feature products made from each of these plants so the students actually get to touch the fibres to see what they feel like, and why one might be used for one thing over another (for example, it would be extremely unlikely for you to want to wear a pair of jeans made out of sisal, but some made out of hemp would be lovely).

Sisal, also commonly called "agave" after it's Latin name, is native to the Yucatan area in Mexico where it is still commonly cultivated (and found in the wild) today. There are many, many other countries that cultivate this plant for its fibres, not the least of which being my favourite country to visit in the whole wide world: Cuba. The story of how they started farming sisal is actually a funny one! Back in the "good old days" (the 1600s and 1700s, not the 1980s), world exploration was quite the hot topic everywhere in the world. Cuban people, whether it be immigrants to Cuba who have now called it home for decades or native Cubans who have lived there for centuries, were big into exploration after Christopher Columbus piqued their interest (he made landfall in Trinidad in Cuba, where he was attracted by all of the same plants he found in the Dominican Republic). They set sail for the west, hoping to come across something exciting and they did: Mexico. What they observed there was fascinating to them; people turning plants into beverages, and then singing and dancing after consuming those beverages. I don't know about you, but it sounds like a fun time to me! Cubans agreed, and offered to buy some of these plants off of their hands; Mexico refused. So what's a Cuban to do when you want to make the "happy drink" but they won't give you the plant to make it? Why you steal it, that's what you do. Minor detail: the plant in question was the plant called Agave tequilana, or perhaps even Agave americana, not Agave sisilana. Since pretty much all green spiky plants look the same after an over-indulgence of tequila, you can probably understand how they got the two mixed up. Once they brought the plants back to Cuba, grew them, and tried fermenting them into alcohol they were likely sorely disappointed since the resulting beverage would taste nothing like Mexican tequila (it's much more bitter, and would be a much darker brown). They quickly rectified their mistake by becoming one of the world's most important producers of sisal fibres around the world, used to make marine ropes and twine. At least it wasn't all for nothing!

Sisal has recently come back into fashion as an alternative plant to grow in an area, especially in tropical countries, when you're letting a field plot go to rehabilitate the soil as it out-competes weeds and animals avoid eating it because of its physical defenses. It will just happily grow, producing long strands of fibres in the leaves without any kind of human intervention. Even harvesting the plant for fibre is non-destructive; you simply cut the leaves from the stem and leave the stem to grow more leaves. Most commercial sisal varieties are sterile, meaning they will never produce the flower stalk that is so characteristic of other members of the genus Agave (which you can read all about HERE or a closely related plant in a different genus HERE). Should those flowers have been produced, the flower stalk could also be used as a source of fibre. Like with the tequila agave, once the flower stalk is produced and the flowers are pollinated, the entire plant dies so there is incentive for sterile varieties to be grown to prolong the life of the plant.

Aside from rope, there are many uses for sisal and even more are being discovered now that varieties of sisal can be produced in the lab that make longer, softer fibres. Sisal is now commonly used to make paper, dartboards, scouring cloths and sponges, filters, carpets, and even some texturized wall coverings (paints and wallpapers). Sounds like a great plant! The one major downside in using this plant as a fibre source is the amount of waste: only about 4% of the total mass of the plant are useable fibres. The rest is all waste that is composted (rarely) or burned (more likely). The odd time the burning of sisal waste will turn into a dirty fuel, but more often than not it's just set on fire in the field and the ashes are spread around after the pile has been burned off. There are now efforts into looking at how microbial decay by bacteria can be used to turn sisal wastes into biogas, or methane.

While not officially a state "tree" (not actually a tree, despite the ability to produce a stem that looks quite woody, as it is a monocot), it appears on the coat of arms of the state of Yucatan in Mexico, and Barquisimeto in Venezuela.