It’s official: weeds have magic!

By Rebecca Du, 2020 alumni.

Have you ever tried to kill weeds in your backyard? No matter how thorough you worked, they just popped up later. Well, they are protected by magic, the evilest kind, like he-who-must-not-be-named from Harry Potter.

Yes! The weeds have horcruxes!!! Lord Voldemort made seven of those, with each holding a piece of his soul. Even he is killed, he can always be brought back to life using one of the horcruxes.

Similar to those, weeds’ horcruxes contain the most important piece, the complete DNA sequence, and are able to grow into a new plant, like resurrection. There is no way you can kill all weeds until you destroy all the horcruxes.

You Know Who. By James_Seattle from Flickr

Are you ready for your challenges?

First horcrux: seed

Each seed contains all resources to grow into a whole new plant. Most plants produce seeds, but weeds bring that to an epic level. Summer Grass (Digitaria sanguinalis) can produce 150,000 seeds per plant. Just imagine if wheat could produce half of that amount, no more hunger all around the world!

Summer Grass and its flowers. Photos by Matt Lavin from Flickr (left and right)

Second horcrux: bulb

Some weeds have hidden horcruxes underground other than seeds. Bermuda Buttercup (Oxalis pes-caprae) produce bulbs in soils, like tiny onions. Just when you think you have pulled them all, they may pop up some day from bulbs.

Bermuda Buttercup plant and its underground bulbs. Photos by Zachi Evenor from Flickr (left) and Daniel Feliciano from Wikimedia Commons (right)

Third horcrux: tuber

Tuber is special stem or root with ability to grow new plants. Most of tubers are underground, just like potatoes. But there are exceptions. Chinese Yam (Dioscorea oppositifolia) produces many tiny “air potatoes” above ground. When they are ripe, they fall off and grow into new plants. It has been defined as weed in north America for many years. As Chinese, I have to say, those tiny potatoes are delicious. Just steam and go.

Air potatoes on Chinese Yam. Photo by Bob Richmond from Flickr

Fourth horcrux: rhizome

Rhizomes are underground stems (just think about ginger) with ability to grow into new plants. When you yank a weed with rhizomes, you remove the part aboveground but break its rhizomes underground into pieces. Each of them will grow into a new plant. Instead of removing it, you help it produce more.

Japanese knotweed (Fallopia japonica) is a good example. Its rhizomes can survive temperatures of −35 °C and can extend 7 meters horizontally and 3 meters deep. It is almost impossible to remove.

Japanese Knotweeds grow from rhizomes in Spring. Photo by Dan Nydick from Flickr

Fifth horcrux: corm

Corms are special stems storing energy and have the ability to grow into new plants. Onion Grass (Romulea rosea) is a prolific seed producer and has underground corms. Similar to plants with rhizomes, it can’t be removed completely by yanking. It is now very common in Melbourne. Look at lawns carefully, you may find them in spring with beautiful pink-violet flowers.

Onion Grass flowers, seeds and whole plant with corm. Photos by Andrew Massyn from Wikimedia Commons (left) and Harry Rose from Flickr (middle and right)

Fortunately, we have extra help. Cockatoos enjoy ploughing up the ground to get at the corms for snacks.

Corm Destroyer Squad. Photo by Abhishek Gopalakrishnan on Unsplash

Generally, a weed is a plant growing in the wrong place, no matter how attractive they appear.

In crop fields, they compete with crops for nutrients, water and even space. The resources we put in will go to weeds other than our food.

In natural reserves, they compete with native plants and even change the soil characteristics. Once soil changes, it might not be suitable for native species to grow any more. Eventually weeds may take over and occupy the whole area. All animals relying on those native plants will be severely affected.

Scientists have been working hard to understand the mechanism of weeds and hopefully will come up with more effective ways of managing weeds. Meanwhile, everyone can pitch in and help. Removing weeds from your backyard would be a great start.

Find out more about weeds here in Victoria: Priority weeds