My first encounter with this startling plant was during my years in rural Laos. Wong’s youngest, Kongngeun, was halfway up a ladder poised against a mango tree. With machete in hand, her tiny bare feet toddled on its rickety bamboo rungs. I lifted her down and put away the ladder. Scarcely understanding the consequences of what was to transpire, she bumbled towards me, her bright eyes sparkling and her great blade swinging. To this day I wonder what she was feeling. Her two-year old face seemed full of innocence, without a speck of anger. And yet, the machete arced fatefully towards my protesting hand.
Moments stretched out—in vain —as its metal edge approached and then lodged itself into the top of my thumb. Her face melted into fear. Wasting no time to scold, Wong sprinted to a nearby pineapple field and emerged seconds later with a clump of bright green leaves. I recognised the plant immediately as Nya Falang; that sticky, pungent plant I had spent months weeding in a nearby Mulberry orchard. He chewed it into paste and slathered it onto my gushing wound. The bleeding stopped immediately. Thumb bandaged, I later reflected on what had happened.
Speeding up platelet aggregation (the mechanism I supposed in play), slows down bleeding. Two opposing rates of change held together a single process. In scientific articles, I later learned Chromolaena odorata accomplished this hemostatic feat by changing the rate of activity of some genes in my thumb’s fibroblasts (Pandith et al, 2013). Different temporal shifts coordinated across different biological scales. The protagonists in this timeshifting wizardry are stigmasterol, scutellarein tetramethyl ether, flavonoids, and chromomoric acid, which seem to serve antiherbivory and antibacterial roles in the plant’s defense (Vijayaraghavan et al, 2017). Incidentally, these chemicals are likely toxic to the plant itself, and so are normally stowed away in the plant cells’ vacuoles. Wong’s teeth had to cut the cells open so the plant could heal my own cut open cells.
C. odorata’s regional names hint at its sharp and then hemorrhagic arrival into various people’s natural history. Known as ‘French Weed’ (ຫຍ້າຝະຣັ່ງ, Nya Falang) in Laos, but as ‘Herbe de Laos’ in France, C. odorata is actually native to Central America, the Caribbean, and the Northern part of South America. Since the mid 20th century, it has spread rapidly, with now pan-continental distribution in tropical and subtropical climates (though apparently with minimal presence in Australia). When I google ‘world’s worst tropical weeds,’ C. odorata comes up ahead of other notorious troublemakers of the global South, including Imperata cylindrica, Cyperus rotundus, Commelina benghalensis, and Eichhornia crassipes. Its prolific habits damage cropland, lay waste to pasture, and ruin plantation productivity. The same chemicals that saved me a long and bumpy journey to a local health centre and perhaps a serious infection, undoubtedly contribute to its ecological success and its reputation as a scourge.
Emerson’s (1880) notion that ‘a weed is a plant whose virtues have never been discovered’ will seem naive and dangerous to most farmers. I have seen enough family crops cramped and cluttered into oblivion to sympathise with those who despise C. odorata. Nevertheless, I have benefited from the virtues of this pungent coagulator. Not only did it heal my hand, it thrust into consciousness the surprise of discovering hidden powers in commonplace things. The humdrum prevalence and perhaps even the menace of highly successful plants sets them up to shatter our preconceptions all the more forcefully. We should be grateful for these ruptures and, indeed, seek them out.
I do not mean to suggest there is no place for controlling this or any other weed. Agriculture, in any foreseeable future, depends on it. But I wonder if it is possible to appreciate even the vigorous plants we commit to weaken or kill, that their life be taken through acts that pierce hatred with gratitude, to speckle their tedious annihilation with flecks of wonder.
References
Emerson, R.W. (1880) Fortune of the Republic, in Prose Works. Boston, MA: Houghton, Osgood & Co.
Pandith, H.; Zhang, X.; Liggett, J.; Min, K-W, Gritsanapan, W. & Baek, S.J. (2013) ‘Hemostatic and Wound Healing Properties of Chromolaena odorata Leaf Extract’, ISRN Dermatology Article ID168269, pp. 1-8.
Vijayaraghavan, K.; Rajkumar, J.; Bukhari, S.N.D.; Al-Sayed, B. & Seyed, M.A. (2017). ‘Chromolaena odorata: A neglected weed with a wide spectrum of pharmacological activities’, in Molecular Medicine Reports, vol.15:3, pp. 1007-1016.